The 1997 North American interagency Intercomparison of Ultraviolet Spectroradiometers including narrowband filter radiometers.
The fourth North American North American
named after North America.
North American blastomycosis
see North American blastomycosis.
North American cattle tick
see boophilusannulatus. Intercomparison In`ter`com`par´i`son
n. 1. Mutual comparison of corresponding parts. of Ultraviolet An invisible band of radiation at the upper end of the visible light spectrum. With wavelengths from 10 to 400 nm, ultraviolet starts at the end of visible light and ends at the beginning of X-rays. The primary source of ultraviolet light is the sun. Monitoring Spectroradiometers was held September September: see month. 15 to 25, 1997 at Table Mountain outside of Boulder, Colorado The City of Boulder (, Mountain Time Zone) is a home rule municipality located in Boulder County, Colorado, United States. Boulder is the 11th most populous city in the State of Colorado, as well as the most populous city and the county , USA. Concern over stratospheric strat·o·spher·ic
1. Of, relating to, or characteristic of the stratosphere.
2. Extremely or unreasonably high: "money borrowed at today's stratospheric rates of interest" ozone depletion Ozone depletion describes two distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total amount of ozone in Earth's stratosphere since around 1980; and a much larger, but seasonal, decrease in stratospheric ozone over Earth's polar regions has prompted several government agencies in North America North America, third largest continent (1990 est. pop. 365,000,000), c.9,400,000 sq mi (24,346,000 sq km), the northern of the two continents of the Western Hemisphere. to establish networks of spectroradiometers for monitoring solar ultraviolet irradiance ir·ra·di·ant
Sending forth radiant light.
[Latin irradi at the surface of the Earth. The main purpose of the Intercomparison was to assess the ability of spectroradiometers to accurately measure solar ultraviolet irradiance, and to compare the results between instruments of different monitoring networks. This Intercomparison was coordinated by NIST (National Institute of Standards & Technology, Washington, DC, www.nist.gov) The standards-defining agency of the U.S. government, formerly the National Bureau of Standards. It is one of three agencies that fall under the Technology Administration (www.technology. and NOAA NOAA
National Oceanic and Atmospheric Administration
Noun 1. NOAA - an agency in the Department of Commerce that maps the oceans and conserves their living resources; predicts changes to the earth's environment; , and included participants from the ASRC ASRC Arctic Slope Regional Corporation
ASRC Asynchronous Sample Rate Converter
ASRC Advanced Simulated Radar Client
ASRC American Studies Research Centre
ASRC Alabama Society for Respiratory Care
ASRC Arkansas Society for Respiratory Care , EPA EPA eicosapentaenoic acid.
n.pr See acid, eicosapentaenoic.
n. , NIST, NSF NSF - National Science Foundation , SERC SERC - Science and Engineering Research Council , USDA USDA,
n.pr See United States Department of Agriculture. , and YES. The UV measuring instruments included scanning spectroradiometers, spectrographs, narrow band multi-filter radiometers, and broadband broadband
Term describing the radiation from a source that produces a broad, continuous spectrum of frequencies (contrasted with a laser, which produces a single frequency or very narrow range of frequencies). radiometers. Instruments were characterized char·ac·ter·ize
tr.v. character·ized, character·iz·ing, character·iz·es
1. To describe the qualities or peculiarities of: characterized the warden as ruthless.
2. for wavelength accuracy, bandwidth, stray-light rejection, and spectral spectral /spec·tral/ (spek´tral) pertaining to a spectrum; performed by means of a spectrum.
Of, relating to, or produced by a spectrum. irradiance responsivity Responsivity measures the input–output gain of a detector system. For a system that responds linearly to its input, there is a unique responsivity. For nonlinear systems, the responsivity is the local slope (derivative). . The spectral irradiance responsivity was determined two to three times outdoors to assess temporal Having to do with time. Contrast with "spatial," which deals with space. stability. Synchronized syn·chro·nize
v. syn·chro·nized, syn·chro·niz·ing, syn·chro·niz·es
1. To occur at the same time; be simultaneous.
2. To operate in unison.
1. spectral scans of the solar irradiance were performed over several days. Using the spectral irradiance responsivities determined with the NIST traceable standard lamp standard lamp
a tall electric lamp that has a shade and stands on a base
standard lamp n (BRIT) → lámpara de pie
standard lamp n ( , and a simple convolution convolution /con·vo·lu·tion/ (-loo´shun) a tortuous irregularity or elevation caused by the infolding of a structure upon itself. technique with a Gaussian Gaussian
A system whose probabilities are well described by the normal distribution, or bell shaped curve. slit-scattering function to account for the different bandwidths of the instruments, the measured solar irradiance from the spectroradiometers excluding the filter radiometers at 16.5 h UTC (Coordinated Universal Time, Temps Universel Coordonné) The international time standard (formerly Greenwich Mean Time, or GMT). Zero hours UTC is midnight in Greenwich, England, which is located at 0 degrees longitude. had a relative standard deviation In probability theory and statistics, the Relative Standard Deviation (RSD or %RSD) refers to the absolute value of the coefficient of variation expressed as a percentage.
It is widely used in analytical chemistry to express the precision of an assay.
l of [+ or -]4 % for wavelengths greater than 305 nm. The relative standard deviation for the solar irradiance at 16.5 h UTC including the filter radiometer radiometer (rā'dēŏm`ətər), instrument for detection or measurement of electromagnetic radiation; the term is applied in particular to devices used to measure infrared radiation. was [+ or -]4 % for filter functions above 300 nm.
Key words: environmental monitoring; intercomparison; solar ultraviolet; spectroradiometers.
Concern over the effects of changes in solar ultraviolet (UV) radiation on biological ecosystems, humans, and materials has prompted several government agencies in North America to develop UV Monitoring Networks and research programs to address the current and long-term Long-term
Three or more years. In the context of accounting, more than 1 year.
1. Of or relating to a gain or loss in the value of a security that has been held over a specific length of time. Compare short-term. impacts of these changes (1, 2). Detecting long-term trends in solar ultraviolet irradiance requires accurate measurements of the absolute irradiance, for individual instruments, for an entire network, and between networks (3).
The North American Interagency in·ter·a·gen·cy
Involving or representing two or more agencies, especially government agencies. Intercomparisons of Ultraviolet Monitoring Spectroradiometers are performed near Boulder, Colorado, to assess the ability of spectroradiometers to accurately measure solar ultraviolet irradiance and to compare these results between instruments of different monitoring networks on an annual or bi-annual basis. The first such Intercomparison was held September 19 to 29, 1994; the second Intercomparison was held June June: see month. 12 to 23, 1995; and the third Intercomparison was held June 15 to 25, 1996. The experimental details and results from these efforts have been described previously (4, 5, 6). Results from the fourth Intercomparison, held September 17 to 25, 1997, are presented here. This Intercomparison was coordinated by the Optical Technology Division of the National Institute of Standards and Technology National Institute of Standards and Technology, governmental agency within the U.S. Dept. of Commerce with the mission of "working with industry to develop and apply technology, measurements, and standards" in the national interest. (NIST) and the Surface Radiation Research Branch (SRRB SRRB Spares Requirements Review Board
SRRB Specification Requirements Review Board ) of the National Oceanic and Atmospheric Administration Noun 1. National Oceanic and Atmospheric Administration - an agency in the Department of Commerce that maps the oceans and conserves their living resources; predicts changes to the earth's environment; provides weather reports and forecasts floods and hurricanes and (NOAA). The following agencies and organizations participated: the Natio nal UV Monitoring Center (NUVMC NUVMC National Ultraviolet Monitoring Center (University of Georgia) ) at the University of Georgia Organization
The President of the University of Georgia (as of 2007, Michael F. Adams) is the head administrator and is appointed and overseen by the Georgia Board of Regents. which administers the Environmental Protection Agency's (EPA) UV Network, the National Institute of Standards and Technology (NIST), Biospherical Instruments which administers the National Science Foundation's (NSF) CV Monitoring Network for Polar Regions polar regions: see Antarctica; Arctic, the. , the Smithsonian Environmental Research Center The Smithsonian Environmental Research Center (SERC) is a 2,800-acre environmental research and educational facility operated by the Smithsonian Institution located in Edgewater, MD on the Rhode and West Rivers. (SERC), the Natural Resource Ecology ecology, study of the relationships of organisms to their physical environment and to one another. The study of an individual organism or a single species is termed autecology; the study of groups of organisms is called synecology. Laboratory (NREL NREL National Renewable Energy Laboratory
NREL Natural Resource Ecology Laboratory (Colorado State University, Fort Collins, CO) ) of Colorado State University Colorado State University, at Fort Collins; land-grant with state and federal support; chartered 1870, opened 1879 as an agricultural college, assumed present name in 1957. There is a veterinary teaching hospital, an agricultural campus, and a research campus. (CSU See DSU/CSU.
1. CSU - California State University.
2. CSU - Cleveland State University.
3. CSU - Channel Service Unit. ) which administers the Department of Agriculture's (USDA) UV Monitoring Network (7), the Atmospheric atmospheric /at·mos·pher·ic/ (at?mos-fer´ik) of or pertaining to the atmosphere.
of or pertaining to the atmosphere. Sciences Research Center (ASRC) of the State University of New York (body) State University of New York - (SUNY) The public university system of New York State, USA, with campuses throughout the state. (SUNY SUNY - State University of New York ) which represents the USDA monitoring program, and Yankee Yankee, term used by Americans generally in reference to a native of New England and by non-Americans, especially the British, in reference to an American of any section. Environmental Systems, Inc. (YES) which manufacturers a variety of UV instruments used in UV monitoring networks and for atmospheric UV research. A list of attendees is given in Appendix A.
As in previous years, the Years, The
the seven decades of Eleanor Pargiter’s life. [Br. Lit.: Benét, 1109]
See : Time goal of the Intercomparison was to track the comparison of UV irradiance measured by instruments that are part of UV Monitoring Networks. Unlike other years, there was an emphasis on new prototype instruments for measuring and monitoring of UV irradiance, which precluded a true "blind" comparison of solar irradiance data because of a lack of current participant calibration calibration /cal·i·bra·tion/ (kal?i-bra´shun) determination of the accuracy of an instrument, usually by measurement of its variation from a standard, to ascertain necessary correction factors. data for several of the instruments. Synchronized solar scans from each instrument were compared based upon responsivity calibrations performed by NOAA. Measurements of the spectral irradiance responsivity checked the absolute irradiance scales used by the networks and provided a common scale for the synchronized measurements of solar irradiance. As with the other Intercomparisons, these synchronized solar irradiance measurements were the most important aspect of the fourth Intercomparison as they allow assessment of the present limits to which irradiance determined by different instruments can be compared. Instru ment parameters characterized included wavelength uncertainty as a function of wavelength, stray-light rejection, the slit-scattering function, bandwidth as a function of wavelength, and spectral irradiance responsivity. A field calibration unit was used for the spectral irradiance responsivity measurements which has been shown to reduce uncertainties of the responsivity for this experiment (8). Other instruments determined the atmospheric conditions during the Intercomparison, which is useful for correlating these conditions with the measured solar ultraviolet irradiance. A list of all the instruments present at the Intercomparison is given in Table 1.1. Please note the times given in this paper are in Universal Coordinated Time (UTC), 6 h ahead of Mountain Daylight Time, the local time.
2. Site Description
The site of the Intercomparison was at the Table Mountain Test Facility (TMTF TMTF Temporal-Modulation Transfer Function
TMTF Tidemark Tekniske Fagskole (Porsgrunn, Norway school)
TMTF Transition Management Task Force ), a plateau plateau, elevated, level or nearly level portion of the earth's surface, larger in summit area than a mountain and bounded on at least one side by steep slopes, occurring on land or in oceans. owned by the Federal government approximately 12.9 km north of Boulder, Colorado and 5.6 km east of the Front Range of the Rocky Mountains Rocky Mountains, major mountain system of W North America and easternmost belt of the North American cordillera, extending more than 3,000 mi (4,800 km) from central N.Mex. to NW Alaska; Mt. Elbert (14,431 ft/4,399 m) in Colorado is the highest peak. . This site was chosen because of its good view to the horizon, the presence of laboratory facilities, and the proximity of facility and staff support at both NIST and NOAA in Boulder Boulder, city, United States
Boulder, city (1990 pop. 83,312), seat of Boulder co., N central Colo.; inc. 1871. A Rocky Mountain resort and a suburb of Denver, it is the seat of the Univ. of Colorado (1876). .
For the synchronized measurements of solar irradiance, the spectroradiometers except the UV-Multi Filter Rotating ro·tate
v. ro·tat·ed, ro·tat·ing, ro·tates
1. To turn around on an axis or center.
2. Shadowband Radiometers (UV-MFRSR) were located on individual concrete pads on the south side of the plateau at latitude latitude, angular distance of any point on the surface of the earth north or south of the equator. The equator is latitude 0°, and the North Pole and South Pole are latitudes 90°N and 90°S, respectively. 40.125[degrees] N, longitude longitude (lŏn`jĭtd'), angular distance on the earth's surface measured along any latitude line such as the equator east or west of the prime meridian. 105.237[degrees] W, and elevation elevation, vertical distance from a datum plane, usually mean sea level to a point above the earth. Often used synonymously with altitude, elevation is the height on the earth's surface and altitude, the height in space above the surface. 1689 m. The pads were arranged in an east-west line and were 2.4 m square and 12.2 m between centers. The UV-MFRSRs were located at NOAA/SRRB's site on an elevated platform 50 m to the west of the pads. The highest, and only major, obstruction obstruction /ob·struc·tion/ (ob-struk´shun)
1. the act of blocking or clogging.
2. block; occlusion; the state or condition of being clogged.obstruc´tive
n. to the horizon was a peak 5.6 km due west of the pads with a 5.1[degrees] angle of inclination Noun 1. angle of inclination - (geometry) the angle formed by the x-axis and a given line (measured counterclockwise from the positive half of the x-axis)
geometry - the pure mathematics of points and lines and curves and surfaces . Temporary trailers approximately 30 m south of the pads housed the data acquisition and control computers and equipment for the spectroradiometers. The plateau has a downward slope to the south of the pads, so the tops of the trailers were below the elevation of the pads. At the Intercomparison, pyranometers, pyrgeometers, UVB UVB ultraviolet B; see ultraviolet. radiometers, shadowband radiometers and a total sky imager (TSI TSI Total Solar Irradiance (sum solar light in energy per unit of time)
TSI Trading Standards Institute (UK)
TSI Transportation Safety Institute (US DOT) ) were located on the platform. A meteorological me·te·or·ol·o·gy
The science that deals with the phenomena of the atmosphere, especially weather and weather conditions.
[French météorologie, from Greek tower, recording the temperature, relative humidity relative humidity
The ratio of the amount of water vapor in the air at a specific temperature to the maximum amount that the air could hold at that temperature, expressed as a percentage. , atmospheric pressure atmospheric pressure
or barometric pressure
Force per unit area exerted by the air above the surface of the Earth. Standard sea-level pressure, by definition, equals 1 atmosphere (atm), or 29.92 in. (760 mm) of mercury, 14.70 lbs per square in., or 101. , and wind speed and direction at the site was located approximately 90 m north-west Adv. 1. north-west - to, toward, or in the northwest
north-west n → noroeste m
north-west north n → nord-ouest of the pads. Finally, a concrete building immediately to the southwest of the platform was used for servicing the instruments and holding meetings. A dome at the western end of the building was covered with a black cloth to eliminate reflections from it to the instruments.
3. Instrument Descriptions
For clarity in this paper, spectroradiometers refer to instruments capable of measuring irradiance at particular spectral wavelengths and includes the scanning instruments, the spectrograph instruments, and the narrow-band filter instruments (9). In total, eleven UV measuring spectroradiometers participated at the Intercomparison. Six scanning spectroradiometers participated at the Intercomparison. These included two Brewer Spectrophotometers, (1) Model MKIV, serial numbers 101 and 114, operated by the participants from NUVMC at the University of Georgia, which manage the EPA LIV Network; a UV Spectroradiometer developed and operated by participants from NIST; a Biospherical Instruments SUV-150 Ultraviolet Spectroradiometer, serial number 11-002, operated by participants from Biospherical Instruments which administer the NSF network; a Smithsonian Smith`so´ni`an
a. 1. Of or pertaining to the Englishman J. L. M.
A word typically made up of the first letters of two or more words; for example, BASIC stands for "Beginners All purpose Symbolic Instruction Code. conveys the UV Network or manufacturer followed by the instrument type or serial number. Table 3.1 lists the characteristics of each instrument, and descriptions are given below. The two Brewer spectroradiometers, the SERC multi-filter radiometer, and the UV-MFRSRs were described in detail earlier (4, 5, 6, 10) and therefore only a cursory cur·so·ry
Performed with haste and scant attention to detail: a cursory glance at the headlines.
[Late Latin curs description is given below. The other instruments are given a more detailed description in this paper or an appropriate reference is cited.
3.1 Brewer Spectrophotometer spectrophotometer, instrument for measuring and comparing the intensities of common spectral lines in the spectra of two different sources of light. See photometry; spectroscope; spectrum.
Two Sci-Tec Brewer spectrophotometers (Model MKIV) participated at the Intercomparison that measure total solar ultraviolet irradiance from 286.5 nm to 363 nm and total column [O.sub.3], [SO.sub.2], and [NO.sub.2] from both direct sun and zenith zenith, in astronomy, the point in the sky directly overhead; more precisely, it is the point at which the celestial sphere is intersected by an upward extension of a plumb line from the observer's location. sky measurements at specific wavelengths. A right-angle prism directs light from one of several sources, either internal calibration lamps, the sky, or a Teflon Teflon, trade name for a solid, chemically inert polymer of tetrafluoroethylene (C2F4), F2C=CF2. Stable up to temperatures around 572°F; (300°C;), Teflon is used in electrical insulation, gaskets, and in making diffuser dif·fus·er
1. One that diffuses, as:
a. A light fixture, such as a frosted globe, that spreads light evenly.
b. A medium that scatters light, used in photography to soften shadows.
c. , along the optical path. This path contains apertures, filters, and lenses that focus the light onto the entrance slit of a single-grating modified Ebert-type monochromator A monochromator is an optical device that transmits a mechanically selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input. .
The exit slit focal plane The plane, perpendicular to the optical axis of the lens, in which images of points in the object field of the lens are focused. of the monochromator contains six slits, five for selecting the wavelengths for determining the total column amounts and one for wavelength calibration. A slotted cylindrical cyl·in·dri·cal
Of, relating to, or having the shape of a cylinder, especially of a circular cylinder. slit-mask in front of the exit slit plane serves as the wavelength selector (programming) selector - 1. In Smalltalk or Objective C, the syntax of a message which selects a particular method in the target object.
2. An operation that returns the state of an object but does not alter that state. . The nominal bandwidth, set by the exit slits, is 0.6 nm. For the Model MKIV Brewer spectrophotometer, the diffraction grating A device that breaks up an electromagnetic wave into its different frequencies (wavelengths) by scattering them at different angles. For example, a series of thousands of scored lines in a glass plate diffracts light into a rainbow of colors. operates in third order for UV spectral scans and [O.sub.3] and [SO.sub.2] measurements and second order for [NO.sub.2] measurements. Light from the exit slit passes through a lens and a filter before focusing onto the cathode of a photomultiplier tube A vacuum tube that converts light into electrical energy and amplifies it. Photomultiplier tubes are used in high-end drum scanners, because they are more sensitive to light than the CCD elements used in lower-cost devices. (PMT See photomultiplier tube. ). The photon pulses from the PMT are amplified, discriminated, and divided by the slit-mask cycle before being transmitted to the counter. For wavelengths shorter than 325 nm the MKIV model uses a [NiSO.sub.4] filter sandwiched between two Schott schott
See shott. UG-1 1 filters, and a single UG-11 filter for longer wavelengths.
The wavelength of the monochromator in terms of micrometer micrometer (mīkrŏm`ətər, mī`krōmē'tər).
1 Instrument used for measuring extremely small distances. steps of the instrument is determined at the factory from the wavelengths of Hg emission lines. The wavelength registration of the monochromator is periodically checked and adjusted throughout a day by scanning the micrometer forward and backward about the 302.3 nm line from the internal Hg calibration lamp. The EPA Network uses a set of lamps, housing, and power supply furnished fur·nish
tr.v. fur·nished, fur·nish·ing, fur·nish·es
1. To equip with what is needed, especially to provide furniture for.
2. by the manufacturer for stability checks. These are 50 W quartz-halogen lamps mounted horizontally 5 cm above the diffuser in a housing and operated at a constant 12 V.
Biospherical Ultraviolet Spectroradiometer
The Biospherical SUV- 150 11-002 Ultraviolet Spectroradiometer is a 150 mm f/4.4 Czerny-Turner double monochromator that employs a grating blazed at 240 nm with 2400 grooves Grooves is an American electronic music magazine founded in 1999 by editor Sean Portnoy, initially concentrating on the then-burgeoning IDM music genre and expanding to its more experimental, abstract offshoots, such as microsound, microhouse and glitch, eventually per millimeter One thousandth of a meter, or 1/25th of an inch. See metric system. . The instrument has a nominal bandwidth of 0.7 nm and typically scans from 280 um to 600 nm in 0.2 nm steps, taking approximately 16 minutes to complete a scan. A schematic A graphical representation of a system. It often refers to electronic circuits on a printed circuit board or in an integrated circuit (chip). See logic gate and HDL. of the SUV-150 is given in Figure 3.1. The SUV-150 utilizes a quartz quartz, one of the commonest of all rock-forming minerals and one of the most important constituents of the earth's crust. Chemically, it is silicon dioxide, SiO2. window with a vacuum-formed Teflon diffuser at the entrance port of an integrating sphere. The diffuser is heated to minimize ice and snow buildup build·up also build-up
1. The act or process of amassing or increasing: a military buildup; a buildup of tension during the strike.
2. . The monochromator is coupled to a 9-stage dynode dy·node
An electrode used in certain electron tubes to provide secondary emission.
[Greek dunamis, power; see dynamic + -ode. R237 1 PMT mounted in a shielded temperature regulated semi-hermetic enclosure enclosure (inclosure) n. land bounded by a fence, wall, hedge, ditch or other physical evidence of boundary. Unfortunately, too often these creations are not included among the actual legally-described boundaries and cause legal problems.
ENCLOSURE. . The temperature is maintained within [+ or -]1 [degrees]C by a thermoelectric ther·mo·e·lec·tric also ther·mo·e·lec·tri·cal
Characteristic of, resulting from, or using electrical phenomena occurring in conjunction with a flow of heat. heater/cooler, driven by a PD controller. The instrument is fully automated au·to·mate
v. au·to·mat·ed, au·to·mat·ing, au·to·mates
1. To convert to automatic operation: automate a factory.
2. and weatherproofed for use in extreme conditions.
The SUV-150 utilizes two internal lamps for wave-length and intensity calibration. The lines from a Hg emission lamp are scanned each day and are used to register the monochromator at the 253.7 nm and 296.7 nm lines and determine the wavelength transfer function. In addition, if needed, several manual Hg lamp scans can be performed by an operator. The other internal calibration source is a 45 W quartz-tungsten-halogen lamp for determining the spectral irradiance responsivity of the instrument. The responsivity is determined in a two-step process since the high voltage The term high voltage characterizes electrical circuits, in which the voltage used is the cause of particular safety concerns and insulation requirements. High voltage is used in electrical power distribution, in cathode ray tubes, to generate X-rays and particle beams, to of the PMT is variable. The spectral irradiance scale is determined by a 200 W DXW-type quartz-tungsten-halogen lamp mounted horizontally 50 cm above the diffuser in a custom enclosure. A spectral scan of this lamp at a fixed high voltage is followed by a spectral scan of the internal 45 W lamp at the same high voltage. This serves to calibrate To adjust or bring into balance. Scanners, CRTs and similar peripherals may require periodic adjustment. Unlike digital devices, the electronic components within these analog devices may change from their original specification. See color calibration and tweak. the internal lamp, and spectral scans of this same lamp at different high voltages determines the res ponsivity under the particular operating condition.
3.3 NIST Ultraviolet Scanning Spectroradiometer
The NIST Ultraviolet Spectroradiometer is one of several double monochromators that were designed and built for NIST in the early 1980s (11, 12, 13). The design uses a 1/8 m Fastie-Ebert monochromator with mirror and grating blanks of Zerodur Zerodur is a registered trademark of Schott Glass Technologies. It is a glass ceramic with an extremely low thermal expansion coefficient (~0.02 x 10-6/K at 0-50°C). to assure thermal stability. A schematic diagram diagram /di·a·gram/ (di´ah-gram) a graphic representation, in simplest form, of an object or concept, made up of lines and lacking pictorial elements. of the optical path is given in Fig. 3.2. This f/5 monochromator utilizes a single rectangular rec·tan·gu·lar
1. Having the shape of a rectangle.
2. Having one or more right angles.
3. Designating a geometric coordinate system with mutually perpendicular axes. grating in a double pass configuration in order to achieve a high degree of wavelength accuracy. In the first monochromator chamber, one end of the rectangular grating is used and in the opposite chamber the other end of the grating is used. Therefore, the double monochromator uses a single grating shaft shaft (shaft) a long slender part, such as the diaphysis of a long bone.
1. An elongated rodlike structure, such as the midsection of a long bone.
2. to change the wavelength in both chambers, minimizing the wavelength uncertainty. This instrument is modular with two Fastie-Ebert monochromators that can be interchanged depending on the measurement project and is easily aligned with the fore-optics and control and drive electronics. The two Fastie-Ebert monochromators employ bl azed holographic gratings A holographic grating is a type of diffraction grating formed by an interference-fringe field of two laser beams whose standing-wave pattern is exposed to a polished substrate coated with photoresist. at 250 nm with 3600 and 1800 grooves per millimeter, respectively. The former grating is used during the Intercomparison with a wavelength range of 290 nm to 325 nm. The slit-widths are fixed and are set for a bandwidth of 0.8 nm.
A separate compartment compartment
a part of the body as a whole and divided from the rest by a physical partition.
that liquid part of the body excluded by cell membranes. Includes intravascular and intercellular compartments. houses the relay optics and attachment of the detectors and entrance fore-optics. A schematic of the entrance and detector detector: see particle detector. relay optics for the spectroradiometer are shown in Fig. 3.3 where the entrance optics of the monochromator have been rotated rotated
turned around; pivoted.
see rotated tibia. 90[degrees] for illustrative il·lus·tra·tive
Acting or serving as an illustration.
Adj. 1. purposes. The entrance fore-optics consists of either an averaging sphere or a transmitting transmitting,
v to send and receive information, signals, and so on; allows a therapist to perceive a client's physical, emotional, and spiritual states. diffuser assembly. The 52 mm averaging sphere has a pressed polytetrafluoroethylene polytetrafluoroethylene
a synthetic material commonly used as a nonstick lining in domestic cooking utensils (frypans); abbreviated PTFE; called also Teflon. Overheating produces toxic fumes that cause an acute hemorrhagic pneumonitis and death in small caged birds, which are (PTFE PTFE
polytetrafluoroethylene. ) coating. A precision aperture An orifice. It often refers to an opening in which light is allowed to pass in optical systems such as cameras and lasers. See f-stop and numerical aperture. (1.004 [cm.sup.2]) is located at the averaging sphere entrance port. An interference filter Interference filter
An optical filter in which the wavelengths that are not transmitted are removed by interference phenomena rather than by absorption or scattering. radiometer views the exit port of the irradiance fore-optics, slightly off-axis from the monochromator viewing geometry geometry [Gr.,=earth measuring], branch of mathematics concerned with the properties of and relationships between points, lines, planes, and figures and with generalizations of these concepts. , and is used to monitor the source stability. The entrance relay optic is a doubly folded spherical spher·i·cal
Having the shape of or approximating a sphere; globular. mirror with unit magnification Magnification
A measure of the effectiveness of an optical system in enlarging or reducing an image. For an optical system that forms a real image, such a measure is the lateral magnification m . A small spherical mirror is used as a collimating relay optic from the exit port to the photomultiplier photomultiplier: see photoelectric cell. (PMT) detector. Two side-window PMTs have been used: a "solar blind" CsTe PMT with low responsivity at wavelengths greater than 310 nm and a bi-alkali PMT with sensitivity to about 650 nm. The former was used at the Intercomparison. The PMT is cooled with a thermoelectric cooler and the PMT signal is measured with photon-counting electronics. The instrument is equipped with temperature sensors
3.4 Smithsonian Ultraviolet Scanning Radiometer
The Smithsonian SR-18 Ultraviolet Scanning Radiometer, serial number UI, measures total solar ultraviolet irradiance at fixed wavelengths selected by 18 interference filters from 290 nm to 324 nm with nominal 2 nm bandwidths. A schematic diagram of the optical path is given in Fig. 3.4. The nominal and actual filter center wavelengths, bandwidths, and maximum transmittances of unit UI are given in Table 3.2. The filters are located on a filter wheel, which rotates at 15 rev/min underneath a Teflon diffuser. Light from the diffuser passes through a filter and is detected by a solar-blind PMT (Hamamatsu Hamamatsu (hämä`mäts), city (1990 pop. 534,620), Shizuoka prefecture, S central Honshu, Japan. R1657) operating in current mode at 20 [degrees]C. The output current is converted to voltage and 14 samples averaged for one minute for each filter, i.e., one spectrum is taken every 4.3 s. The spectral irradiance responsivity is determined at SERC by operating a calibrated cal·i·brate
tr.v. cal·i·brat·ed, cal·i·brat·ing, cal·i·brates
1. To check, adjust, or determine by comparison with a standard (the graduations of a quantitative measuring instrument): 1000 W FEL-type quartz-halogen lamp in the horizontal position horizontal position,
n a posture in which the body lies flat and the feet and head remain on the same level. Also called
supine. centered 50 cm above the diffuser.
3.5. USDA/ASRC U1000 Ultraviolet Spectroradiometer
The USDA reference Ultraviolet Spectroradiometer is a recent prototype design built by ASRC and Instruments SA for use in the USDA UV/Biosphere Network. The monochromator is a 1-meter double Czerny-Turner design with an ion-etched holographic grating operated in first order with 3600 lines per mm. The optical path is given in Fig. 3.5. The detector is a Hamamatsu R237 1-02 PMT with an ASRC-developed dual-threshold photon counting system with a maximum synchronous Refers to events that are synchronized, or coordinated, in time. For example, the interval between transmitting A and B is the same as between B and C, and completing the current operation before the next one is started are considered synchronous operations. Contrast with asynchronous. counting capability of 600 MHz (MegaHertZ) One million cycles per second. It is used to measure the transmission speed of electronic devices, including channels, buses and the computer's internal clock. A one-megahertz clock (1 MHz) means some number of bits (16, 32, 64, etc. . The wavelength range extends from 290 nm to 410 nm. The nominal bandwidth is 0.1 nm and the instrument can operate with a step-size of 0.0005 nm/step and a FWHM FWHM Full Width at Half Maximum of 0.01 nm, preserving a triangular slit function and commensurate com·men·su·rate
1. Of the same size, extent, or duration as another.
2. Corresponding in size or degree; proportionate: a salary commensurate with my performance.
3. throughput The speed with which a computer processes data. It is a combination of internal processing speed, peripheral speeds (I/O) and the efficiency of the operating system and other system software all working together.
1. if carefully aligned. The instrument is capable of an out-of-band Separate from the primary frequency or system. See signaling in/out-of-band and out-of-band data.
1. (communications) out-of-band - The exchange of call control information on a dedicated channel, separate from that used by the telephone call or data transmission. rejection ratio of approximately [10.sup.10]. The measurements at short wavelengths are limited by dark signal and integration time rather than stray Stray
(1) Not a member of the participating party in the trade at hand; (2) not a meaningful indication of a customer's desire to take a sizable position or be involved in a stock. light. At wavelengths greater than 295 nm, the uncertainty in the sign al given by Poisson statistics is less than 5 %, and less than 1 % beyond 299 nm. The diffuser material is PTFE with a diameter of 2.54 cm. Because this instrument is designed for use in the USDA Monitoring Network, the instrument is both automatic and weatherproof.
Calibrations are performed with an external 1000 W FEL FEL - Function Equation Language. Programs are sets of definitions. Sequences are lists stored in consecutive memory. "FEL Programmer's Guide", R. M. Keller, AMPS TR 7, U Utah, March 1982. type lamp by the Central Ultraviolet Calibration Facility (CUCF). The instrument also has two identical 20 W halogen lamps halogen lamp
or tungsten-halogen lamp
Incandescent lamp with a quartz bulb and a gas filling that includes a halogen. It gives brilliant light from a compact unit. in the fore-optics supplied by a non-precision constant voltage source A voltage source is any device or system that produces an electromotive force between its terminals OR derives a secondary voltage from a primary source of the electromotive force. . Later instruments deployed in the network will use a quality constant-current source. In normal operation one of the two identical lamps is designated the working lamp and is automatically checked each night, the other lamp is burned infrequently in·fre·quent
1. Not occurring regularly; occasional or rare: an infrequent guest.
2. , typically once every 2 weeks. At this Intercomparison both were measured each night. Wavelength calibration is completed with an internal Hg low-pressure low-pres·sure
1. Having, working under, or exerting little pressure.
2. Relaxed in attitude, nature, or style; easygoing: a low-pressure lifestyle; a low-pressure personality.
Adj. emission lamp.
3.6. USDA/ASRC Ultraviolet Rotating Multi-Filter Shadowband Radiometer
The UV-MFRSR uses independent interference filter-photodiode detectors and an automated rotating shadowband to measure the direct-normal, total-horizontal, and diffuse-horizontal ultraviolet solar irradiance at seven wavelengths (14). The instrument is manufactured by Yankee Environmental Systems following a similar design developed at the Atmospheric Science Research Center (ASRC) at SUNY, Albany Albany, town, Australia
Albany (ăl`bənē), town (1996 pop. 14,590), Western Australia, SW Australia. It is a port on Princess Royal Harbour of King George Sound. The town has woolen mills and fish canneries. . Three of these instruments, units 270, 386, and 387, participated at the Intercomparison. The prototype unit 270 participated at a previous Intercomparison but has undergone several modifications since then.
The diffuser used to collect the incident radiant flux radiant flux
The rate of flow of radiant energy.
Noun 1. radiant flux - the rate of flow of radiant energy (electromagnetic waves)
flux - the rate of flow of energy or particles across a given surface and the detectors that measure it are located in the sensor A device that measures or detects a real-world condition, such as motion, heat or light and converts the condition into an analog or digital representation. An optical sensor detects the intensity or brightness of light, or the intensity of red, green and blue for color systems. head of the detector assembly. The diffuser is a thin walled Teflon integrating cavity cavity /cav·i·ty/ (kav´i-te)
1. a hollow place or space, or a potential space, within the body or one of its organs.
2. in dentistry, the lesion produced by caries. protruding pro·trude
v. pro·trud·ed, pro·trud·ing, pro·trudes
To push or thrust outward.
To jut out; project. See Synonyms at bulge. above the top of the head and surrounded sur·round
tr.v. sur·round·ed, sur·round·ing, sur·rounds
1. To extend on all sides of simultaneously; encircle.
2. To enclose or confine on all sides so as to bar escape or outside communication.
n. by an artificial horizon to improve the angular angular /an·gu·lar/ (ang´gu-lar) sharply bent; having corners or angles. response of the instrument. Two diaphragms of frosted WG-280 glass in the integrating cavity act as transmission diffusers. Light exiting the bottom of the diffuser is incident on a hexagonal hex·ag·o·nal
1. Having six sides.
2. Containing a hexagon or shaped like one.
3. Mineralogy array of photodiodes with a seventh photodiode A light sensor (photodetector) that allows current to flow in one direction from one side to the other when it absorbs photons (light). The more light, the more the current. Used to detect light pulses in optical fibers and other light-sensitive applications, it works the opposite of a in the center of the array, all with interference filters. The nominal and actual filter center wavelengths and bandwidths of both units are given in Table 3.3. The interior of the head is thermally insulated in·su·late
tr.v. in·su·lat·ed, in·su·lat·ing, in·su·lates
1. To cause to be in a detached or isolated position. See Synonyms at isolate.
2. and has a thermostatic ther·mo·stat
A device, as in a home heating system, a refrigerator, or an air conditioner, that automatically responds to temperature changes and activates switches controlling the equipment. electrical heater that holds the temperature at 45 [degrees]C The shadowband assembly has been described in a previous Intercomparison reference (6). Measurement of the total-horizontal and diffuse-horizontal ultraviolet solar irradiance sequence occu rs three times per minute. The instrument can average over selected time intervals and one minute averages were used for the Intercomparison.
3.7. Ultraviolet Rotating Shadowband Spectrograph (UV-RSS)
Two Ultraviolet Rotating Shadowband Spectrographs (UV-RSS) participated at the Intercomparison, one operated by Yankee Environmental Systems and the second operated by the Atmospheric Sciences Research Center (ASRC). The two spectrographs had comparable designs but the following description is for the ASRC UV-RSS which was the first prototype developed at the Atmospheric Sciences Research Center, SUNY-Albany from its predecessor, the RSS (15). The automated shadowband method (14) allows the instrument to measure quasi-simultaneously diffuse-horizontal and total-horizontal spectral irradiance, guaranteeing identical bandpass and calibration coefficients for the separated components. However, this first UV-RSS prototype was operated without the shadowband attachment during the Intercomparison and measured only the total horizontal irradiance required by the Inter-comparison protocol.
The optical diagram of the UV-RSS is shown in Fig. 3.6. The fore-optics consists of the diffuser/plug integrating cavity (IC) walls from PTFE, and the internal plug forming the bottom surface of the integrating cavity is Spectralon Spectralon reflectance material is a thermoplastic resin that gives the highest diffuse reflectance of any known material or coating over the UV-VIS-NIR region of the spectrum and exhibits highly lambertian behavior. . The design was empirically optimized for Lambertian response and throughput. The exit aperture of the integrating cavity is a 0.300 mm X 3.000 mm rectangle. The solar-blind filter (SBF SBF Studium Biblicum Franciscanum (Franciscan School of Biblical Investigations; Jerusalem, Israel)
SBF Small Block Ford (automotive engine)
SBF Single Black Female
SBF Société des Bourses Francaises ) is made of [NiSO.sub.4] crystal sandwiched between Schott UG-5 glass elements.
The relay lenses (RL1, RL2) are made from UV-grade fused silica fused silica
See quartz glass. . Their purpose is twofold: to match the spectrograph's numerical aperture The measurement of the acceptance angle of an optical fiber, which is the maximum angle at which the core of the fiber will take in light that will be contained within the core. Taken from the fiber core axis (center of core), the measurement is the square root of the squared refractive and to reduce the dynamic range of the incoming signal. The lenses are an aperture stop, reducing stray light in the spectrograph. Their chromatic aberration chromatic aberration: see aberration, in optics.
Fringes of color at the edges of objects in a photograph due to the inability of the camera lens to deal with all wavelengths of light equally. is used intentionally in·ten·tion·al
1. Done deliberately; intended: an intentional slight. See Synonyms at voluntary.
2. Having to do with intention. to reduce the throughput at longer wavelengths; the relay system is focussed to maximize throughput at the 296.7 nm Hg line.
Lenses (L1, L2) and prisms (P1, P2) of the dual-prism spectrograph are also made of the UV-grade fused silica with all primary surfaces polished to 20-10 scratch/dig quality and with multi-layer broadband anti-reflective UV coatings UV coating is the name given to various processes and coverings that utilize or protect against ultraviolet radiation. Ultra-violet coating of paper
Ultra-violet coating is a glossy coating applied over ink printed on paper and dried by exposure to UV radiation. on all primary surfaces. The bases of the prisms remained uncoated to reduce the cost. The throughput of the spectrograph is controlled by the f-number See f-stop. (f/7.5) and the size of the entrance slit (0.050 mm by 2.000 mm).
This prototype used a relatively noisy Noisy is the name or part of the name of six communes of France:
(2) (Mean Opinion Score) The quality of a digitized voice line. It is a subjective measurement that is derived entirely by people listening to the calls and scoring the results from ) linear detector array from Hamamatsu with 512 pixels See pixel. (0.025mm X 2.500mm). This is far from optimum for the UV, but was available and well tested at the time. Subsequently, both standard and UV-RSS instruments use astronomical-grade 1024 X 256 CCD CCD
in full charge-coupled device
Semiconductor device in which the individual semiconductor components are connected so that the electrical charge at the output of one device provides the input to the next device. arrays. The wavelength range is determined by the size of the detector array and magnification of the spectrograph optics. In the UV-RSS, pixel 1 corresponds to 295.8 nm and pixel 512 to 348.8 nm. Later UV instruments with the 1024 X 256 CCD arrays span the range 288 nm to beyond 360 nm. The exposure for the UV-RSS was set to 10 s. Each measurement cycle consisted of one open-shutter (SH) 10 s exposure followed by one closed-shutter 10 s exposure to measure dark signal. After adding the readout (1) A small display device that typically shows only a few digits or a couple of lines of data.
(2) Any display screen or panel. time and data transfer time, the total horizontal irradiance at 512 adjacent wavelengths was acquired every 27.12 s.
The fore-optics and spectrograph are dry-air purged and temperature stabilized sta·bi·lize
v. sta·bi·lized, sta·bi·liz·ing, sta·bi·liz·es
1. To make stable or steadfast.
2. . The former prevents damage to optics and the detector array and the latter improves dark signal and wavelength stability. Wavelength shifts are driven chiefly by the temperature of the prism, thermal stress on the fore-optics, and the air density within the spectrograph. No provision was made on this prototype to control the latter.
The Intercomparison protocol was designed for the common scanning instruments that acquire spectra sequentially. The RSS simultaneously acquires all 512 spectral elements every 27.12 s. Therefore, to obtain comparable results, given time-varying irradiance, pseudo-scans were synthesized syn·the·sized
1. Relating to or being an instrument whose sound is modified or augmented by a synthesizer.
2. Relating to or being compositions or a composition performed on synthesizers or synthesized instruments. from the assembly of RSS exposures to correspond to the scanning instruments' irradiance measurements. On average 50 sequential exposures were used to extract data for one pseudo-scan. The pseudo-scan was synthesized from a diagonal cut of the irradiance surface depicted de·pict
tr.v. de·pict·ed, de·pict·ing, de·picts
1. To represent in a picture or sculpture.
2. To represent in words; describe. See Synonyms at represent. in Fig. 3.7. The 512 points on the diagonal were subsequently interpolated interpolated /in·ter·po·lat·ed/ (in-ter´po-la?ted) inserted between other elements or parts. into the grid of 531 points starting at 295.8 nm every 0.1 nm. The remaining 98 % of the data points produced by the RSS were discarded dis·card
v. dis·card·ed, dis·card·ing, dis·cards
1. To throw away; reject.
a. To throw out (a playing card) from one's hand.
b. as they did not coincide with the time-wavelength points specified by the Intercomparison protocol.
4. Atmospheric Conditions
Weather conditions for the Intercomparison (Julian day “JDN” redirects here. For the military IT system, see Joint Data Network.
The Julian day or Julian day number (JDN) is the integer number of days that have elapsed since the initial epoch defined as noon Universal Time (UT) Monday, January 1, 4713 BC in the 257 - 267) were mostly unfavorable with periods of torrential downpours. During the determination of the slit function, stray-light, and wavelength accuracy the weather was moderately favorable fa·vor·a·ble
1. Advantageous; helpful: favorable winds.
2. Encouraging; propitious: a favorable diagnosis.
3. with predominately clear skies Clear Skies could refer to:
1. Stopping and starting at intervals.
2. rain and downpours. Fortunately, the weather cleared for the final day (267) of the synchronized scans providing an almost cloud-free day.
The temperature, relative humidity, barometric ba·rom·e·ter
1. An instrument for measuring atmospheric pressure, used especially in weather forecasting.
2. Something that registers or responds to fluctuations; an indicator: pressure, and wind speed and direction were recorded at the site of the Intercomparison by the meteorological instruments listed in Table 1.1. During the first few days of the Intercomparison (days 257 to 261), the temperature ranged from 15 [degrees]C in the early morning to nearly 30 [degrees]C in the late afternoon. After the rain clouds moved into the area, the temperature ranged from an average of 5 [degrees]C in the early morning to approximately 12 [degrees]C in the late afternoon (days 262 to 266). On the final day (267) of the synchronized scans when the storm cleared, the temperature varied from 5 [degrees]C in the early morning to nearly 25 [degrees]C in the late afternoon. The relative humidity remained around 30 % prior to the storm, increased to over 100 % during the storm, then dropped from 80 % to 40 % during the clear sky day of 267. The barometric pressure ranged from 83.2 kPa (day 261) to a maximum of 84.4 kPa (day 263).
A set of broadband radiometric instruments, listed in Table 1.1, were located on the test facility platform and made continuous measurements concurrently with the Intercomparison. Results from one solar pyranometer pyranometer (pĭr'ənŏm`ətər), actinometer used to measure the total radiation incident on a surface. are shown in Fig. 4.1, where the irradiance is plotted as a function of time for each day. This solar pyranometer measured total horizontal irradiance from 280 nm to 3000 nm. The clear morning skies and increasing afternoon cloudiness on day 257 are evident in Fig. 4.1. On day 260, inclement in·clem·ent
1. Stormy: inclement weather.
2. Showing no clemency; unmerciful.
in·clem weather moved into the area and remained through day 266 making conditions difficult for determining the responsivity and performing synchronous solar scans. On the night of day 266, the weather cleared and the sky was clear virtually the entire next day.
The EPA Brewer, number 114, determined total column ozone throughout the Intercomparison from measurements of the direct solar beam. The results are shown in Fig. 4.2, where the total column ozone is plotted as a function of time for each day. The vertical bars are the standard deviation In statistics, the average amount a number varies from the average number in a series of numbers.
(statistics) standard deviation - (SD) A measure of the range of values in a set of numbers. of each value. The total column ozone averaged 264 [+ or -] 3 Pa * m (260 matm * cm) on day 260. The sky was too overcast from mid-day Mid-day is an afternoon newspaper in India with editions in Mumbai (Bombay) and Delhi. It was established in 1979 as in a family owned newspaper in Mumbai.
Mid-day is owned by Mid Day Multimedia Ltd. 261 through day 266 for accurate measurements. For the one clear sky day during the Intercomparison, day 267, the total column ozone averaged 267 [+ or -] 3 Pa * m (264 matm * cm).
5. Instrument Characterizations
The spectroradiometers were characterized for the parameters that most affect their ability to accurately measure solar ultraviolet irradiance, and which did not require elaborate experimental equipment or techniques. Therefore, the slit-scattering function, stray-light rejection, wavelength uncertainty, bandwidth, and spectral irradiance responsivity were determined. All of the characterizations were performed outdoors for the instruments on the pads. Previous Intercomparisons demonstrated the need to perform the characterizations outdoors to eliminate moving the instruments after the characterizations. Since detailed mathematical discussions of the characterization A rather long and fancy word for analyzing a system or process and measuring its "characteristics." For example, a Web characterization would yield the number of current sites on the Web, types of sites, annual growth, etc. techniques based upon a simple measurement equation have been given previously (4), they will not be repeated here. Please note that the YES_RSS instrument had instrumental difficulties early in the campaign and therefore the slit-function and stray-light characterization tests In computer programming, a characterization test is a means to describe (characterize) the actual behavior of an existing piece of software, and therefore protect existing behavior of legacy code against unentended changes via automated testing. were not performed on this instrument.
5.1 Slit-Scattering Function and Stray-Light Rejection
5.1.1 Experimental Procedure
An Omnichrome Model 3056 HeCd laser with a single line at 325.029 nm and a nominal power Nominal power is a measurement of a mediumwave radio station's output used in the United States. AM broadcasters are licensed by the Federal Communications Commission to operate at a specific nominal power, which may be (and usually is) different from the transmitter power output. of 18 mW was used to determine both the slit-scattering function and the stray-light rejection of the instruments. The laser was mounted on a tripod, and a box with a hole was placed on top of the instrument. The output of the laser was directed through the hole directly onto the diffuser. The beam diameter The beam diameter of an electromagnetic beam is the diameter along any specified line that is perpendicular to the beam axis and intersects it. For this purpose, the diameter is often defined as the distance between the two diametrically opposite points at which the irradiance is a was approximately the same diameter as the diffusers. The outdoor measurements were performed at twilight twilight, period between sunset and total darkness or between total darkness and sunrise. Total darkness does not occur immediately when the sun sinks below the horizon because light from the sun that strikes the atmosphere is scattered (both by the air itself and by and in the evening to minimize the background signal from the sky.
High-resolution spectral scans were performed near 325 nm to obtain the bandwidth of the instrument, centroid centroid
In geometry, the centre of mass of a two-dimensional figure or three-dimensional solid. Thus the centroid of a two-dimensional figure represents the point at which it could be balanced if it were cut out of, for example, sheet metal. of the line, and shape of the slit-scattering function near its peak. Lower-resolution spectral scans were performed across the entire wavelength ranges of the instruments to obtain the full slit-scattering function. For the SERC instrument, the signals were measured for 4 min. The instruments were configured con·fig·ure
tr.v. con·fig·ured, con·fig·ur·ing, con·fig·ures
To design, arrange, set up, or shape with a view to specific applications or uses: so that the maximum signal did not saturate sat·u·rate
v. Abbr. sat.
1. To imbue or impregnate thoroughly.
2. To soak, fill, or load to capacity.
3. To cause a substance to unite with the greatest possible amount of another substance. the PMT. For the EPA instruments, this involved using an internal neutral-density filter for the high-resolution scans, and then removing the filter from the optical path for the low-resolution scans. A lower-resolution scan was also performed with the laser beam blocked to check for stray light from sources other than the laser. There were no signals greater than the dark signal for any of the instruments.
5.1.2 Data Analysis
The bandwidth of the instrument is defined here as the full-width-at-half-maximum (FWHM) from a high-resolution spectral scan of a laser line or a singlet lamp emission line. Linear interpolation Linear interpolation is a method of curve fitting using linear polynomials. It is heavily employed in mathematics (particularly numerical analysis), and numerous applications including computer graphics. It is a simple form of interpolation. is used to find the wavelengths at which the signal is one-half that of the peak. The bandwidth is then the difference between these two wavelengths.
The centroid method is used to estimate the wavelengths of laser lines and lamp emission lines. The centroid C from a high-resolution scan is given by
C = [summation summation n. the final argument of an attorney at the close of a trial in which he/she attempts to convince the judge and/or jury of the virtues of the client's case. (See: closing argument) over (i)][S.sub.i][[lambda].sub.i]/[summation over (i)][S.sub.i], (5.1)
where i indexes the signals [S.sub.i] and wavelengths [[lambda].sub.i], respectively, of those signals greater than 0.1 of the peak signal. Although baseline The horizontal line to which the bottoms of lowercase characters (without descenders) are aligned. See typeface.
baseline - released version subtraction subtraction, fundamental operation of arithmetic; the inverse of addition. If a and b are real numbers (see number), then the number a−b is that number (called the difference) which when added to b (the subtractor) equals is not important for calculations of the centroid of laser lines because the light is monochromatic monochromatic /mono·chro·mat·ic/ (-kro-mat´ik)
1. existing in or having only one color.
2. pertaining to or affected by monochromatic vision.
3. staining with only one dye at a time. , to maintain consistency with the bandwidths determined by lamp emission lines, baseline subtraction was performed for spectral scans of laser light. A description of the procedure is given in Sec. 5.2.3.
For the high-resolution scans, normalization In relational database management, a process that breaks down data into record groups for efficient processing. There are six stages. By the third stage (third normal form), data are identified only by the key field in their record. of the signals by the peak signal was straight-forward because there is no saturation saturation, of an organic compound
saturation, of an organic compound, condition occurring when its molecules contain no double or triple bonds and thus cannot undergo addition reactions. of the signal. For the low-resolution scans, the peak signals obtained in the high-resolution scans and the optical densities of the filters were used to calculate the peak signals for the scans without the neutral-density filters. The optical density at 325 nm of a neutral-density filter was determined from the common wavelengths at which signals were measured for scans both with and without the filter.
The peak signals obtained in the high-resolution scans were used to normalize normalize
to convert a set of data by, for example, converting them to logarithms or reciprocals so that their previous non-normal distribution is converted to a normal one. the signals from the lowresolution scans for the ASRC_RSS, NIST, NSF_SUV, and USDA_UIK UIK Ust-Ilimsk (Russia)
UIK Underground's Infamous Killaz (Colorado rap/hip-hop group) instruments since there was no saturation. The peak signal for the SERC instrument was not as readily known because there is no filter centered at 325 nm. Therefore, the peak signal for each filter was obtained from the measured signal of the filter centered at the longest wave length that did not saturate. These peak signals were calculated by dividing the measured signal from the filter centered at 320.65 nm by the transmittance of that filter at 325 nm and multiplying mul·ti·ply 1
v. mul·ti·plied, mul·ti·ply·ing, mul·ti·plies
1. To increase the amount, number, or degree of.
2. Mathematics To perform multiplication on. by the peak transmittance of each filter.
5.1.3 Results and Discussion
The bandwidths of the instruments and the centroids The following diagrams depict a list of centroids. A centroid of an object in of the laser line are most useful when included with those values obtained from the scans of the Hg, Cd, and Zn lamps. Therefore, the results from these determinations are shown in Figs. 5.3 and 5.4 in the next section, but to summarize sum·ma·rize
intr. & tr.v. sum·ma·rized, sum·ma·riz·ing, sum·ma·riz·es
To make a summary or make a summary of.
sum , the bandwidths using the 325 nm line of the HeCd laser are close to the nominal values Nominal Value
The stated value of an issued security that remains fixed, as opposed to its market value, which fluctuates.
When referring to fixed-income securities, the nominal value is also the face value. giving 0.53 nm for the ASRC_RSS instrument, 0.58 nm for EPA_101, 0.58 nm for EPA_114, 0.85 nm for the NIST instrument, 0.70 nm for the NSF_SUV instrument, 0.11 am for the USDA_UlK instrument, and 0.61 am for the YES_RSS instrument. These are given in Table 5.1 and the slit-scattering functions are given in Fig. 5.1. The shift in the signal at 325 nm for the EPA_101 and EPA_114 is due to several filter changes at that wavelength. From Fig. 5.1, the slit-scattering functions of the EPA_101, EPA_114, NIST, and USDA_UlK instruments are nearly triangular and symmetric No difference in opposing modes. It typically refers to speed. For example, in symmetric operations, it takes the same time to compress and encrypt data as it does to decompress and decrypt it. Contrast with asymmetric.
(mathematics) symmetric - 1. about the peak wavelength. The wings of the slit function measured with the H eCd laser are chiefly determined by bulk and surface scattering scattering
In physics, the change in direction of motion of a particle because of a collision with another particle. The collision can occur between two charged particles; it need not involve direct physical contact. of the spectrograph optics. The slit-scattering function was not determined for the YES_RSS instrument due to YES_RSS instrumental problems at the time.
The stray-light rejection of each instrument is shown in Fig. 5.2 and is determined from high- and low-resolution scans where the peak-normalized signal is plotted as a function of wavelength. The stray-light rejection is reported for 300 nm in Table 5.1 except for the NIST instrument, which is reported at 320 nm. The stray-light rejection of 3 X [10.sup.-5] and 6 x [10.sup.-5] for instruments EPA_101 and EPA_114 is reasonable for Brewer instruments because they are single-grating instruments. For the NIST and the NSF_SUV instruments, the measurement of the stray-light rejection is probably limited by the dynamic range of the detector and can only be reported as better than [10.sup.-5] and [10.sup.-6], respectively. The ASRC_RSS instrument had a stray-light rejection of approximately 2 X [10.sup.-6], The USDA_UlK instrument is also a double monochromator and has the greatest dynamic range with a measured stray-light rejection of better than 2 X [10.sup.-10]. The stray-light rejection of the SERC instrument of a pproximately 2 x 1 [10.sup.-5] is also reasonable for interference-type filter instruments. The features at 309 nm and 314 nm for the ASRC_RSS instrument result from recycled rays within the prisms that have undergone three internal reflections. Their location is wavelength dependent. Developers of the ASRC_RSS instrument (ASRC SUNY) have suggested that the magnitude of these features could be further reduced with an anti-reflective coating Anti-reflective or antireflection (AR) coatings are a type of optical coating applied to the surface of lenses and other optical devices to reduce reflection. This improves the efficiency of the system since less light is lost. for the prism bases.
5.2 Wavelength Uncertainty
Characterizing the instruments in terms of their response to light from Hg, Cd, and Zn emission line lamps is somewhat more complex than was the case for a HeCd laser because there is a continuum Continuum (pl. -tinua or -tinuums) can refer to:
ultraviolet radiation with a range of 280-320 nanometres region of the solar spectrum the spectrum of solar light, especially as thrown upon a screen in a darkened room. It is characterized by numerous dark lines called Fraunhofer lines.
See also: Spectrum (280 nm to 315 nm) because the irradiance at the Earth's surface Noun 1. Earth's surface - the outermost level of the land or sea; "earthquakes originate far below the surface"; "three quarters of the Earth's surface is covered by water"
surface changes rapidly with wavelength and therefore a small uncertainty in wavelength can translate into a large uncertainty in irradiance.
A distinction needs to be made between wavelength calibration and wavelength registration, both of which affect the wavelength uncertainty. The wavelength calibration for a scanning instrument is the relation between the motor steps that determine the grating angle and the monochromator wavelength, and is determined typically from the emission lines of a Hg lamp. The wavelength calibration for a spectrograph is the pixel to wavelength mapping. The wavelength calibration is in general a non-linear function of motor steps or pixels. The two EPA instruments and the NSF_SUV instrument typically use several Hg lines for wavelength calibration and the ASRC_RSS, NIST, USDA_U1K and YES_RSS instruments use several lines from Hg and Cd lamps for the wavelength calibration. Therefore, the lines from the HeCd laser and the Zn lamp are especially valuable for determining the wavelength uncertainty since typically these are not used for the original calibrations of the instruments. For the scanning instruments, the wave-l ength registration is a fixed offset of motor steps, determined from a known position provided by the 302.3 nm line of Hg for the EPA instruments performed after each solar scan, and the 296.7 nm Hg line for the NSF_SUV instrument performed each day at 0500 UTC. During the Intercomparison, the NIST instrument scanned lines of Hg and Cd as a check after each half hour solar scan to see if the instrument error had exceeded its 0.02 nm uncertainty limit, but no adjustment was necessary. The USDA_UlK instrument scanned the 297.6 nm Hg line after each half hour solar scan as a check but no adjustment was made. The ASRC_RSS instrument externally scanned a HgCd lamp each day to determine the pixel to wavelength mapping.
The wavelengths of emission lines from gas lamps Lighting with gas (methane) with illuminating gas products added for a brighter light, was begun in England in the early 1800s for lighting the streets of cities using coal gas, but its value was soon recognized and use spread to industrial, commercial and residential lighting purposes, are known to a high degree of accuracy. However, the relative intensities of these lines change with lamp and operating condition. An Oriel Model 6035 Hg emission lamp was used because of recent measurements of the relative intensities of the lines from this particular model of lamp (16, 17).
5.2.2 Experimental Procedure
The Hg, Cd, and Zn emission lamps were placed, separately, horizontally and as close as practical over the diffuser of the instrument. The lamps were warmed up for 10 min and the instrument. The lamps were warmed up for 10 min and the instrument performed a spectral scan. The ASRC_RSS, EPA_101, EPA_114, NIST, NSF_SUV, USDA_U1K and YES_RSS instruments performed spectral scans over their entire operating ranges at 0.08 nm, 0.03 nm, 0.04 nm, 0.02 nm, 0.005 nm, and 0.04 nm increments, respectively.
5.2.3 Data Analysis
The bandwidths of the lamp emission lines are calculated as described in Sec. 5.1.2. Baseline subtraction was performed prior to calculation of the bandwidths of the lamp emission lines. This is important for spectral scans of lamp emission lines because of the underlying continuous emission from these lamps. The baseline signal is described by a linear fit of the signals at wavelengths that differ by 1.5 bandwidths from the wavelength of the peak signal. For unresolved multiple lines in emission lamps, the factor is increased from 1.5. to 2.0. The signals and wavelengths for the first five consecutive data points that lie outside this range are averaged and fit with a straight line to yield baseline signal as a function of wavelength. This fit is subtracted from the signals within the range. There is obviously an interplay in·ter·play
Reciprocal action and reaction; interaction.
intr.v. in·ter·played, in·ter·play·ing, in·ter·plays
To act or react on each other; interact. between the baseline subtraction and the bandwidth, but a consistent bandwidth can be obtained after only one or, at most, two iterations between baseline subtraction and the centroid calc ulation. Only the bandwidths for single lines were taken to be indicative of the bandwidth of the instrument at that wavelength. The actual centroids of the lines were calculated from the wavelengths and relative intensities of the lines for that particular model of Hg lamp and from the published values for Cd and Zn (18).
5.2.4 Results and Discussion
The bandwidths calculated from the singlet Hg, Cd, and Zn lines and the HeCd line are plotted in Fig. 5.3 as a function of wavelength. The differences between the calculated and actual centroids of the Hg, Cd, Zn, and HeCd lines are plotted in Fig. 5.4 as a function of wavelength.
The nominal band-pass of the two spectrographs, the ASRC_RSS and the YES_RSS instruments, are approximately 0.6 nm which was designed to coincide with the Brewer spectroradiometer and to improve throughput. Note that later versions of the UV_RSS instruments with the 1024 nm X 256 nm CCD array typically are built to achieve 0.3 nm FWHM at 296.7 nm. The bandwidths of the two spectrographs increase with increasing wavelength by 0.82 %/nm and 0.97 %/nm, and this change is consistent between measurements from the different lamps. The FWHM when expressed in pixels is approximately pixel independent, but when converted to units of nanometers is approximately linear with wavelength. The nominal bandwidths of the USDA_U1K and the NSF_SUV are 0.1 nm and 0.7 nm, respectively, and are essentially wavelength independent. The nominal bandpasses of the EPA and NIST instruments are 0.6 am and 0.8 am, respectively. The bandpasses of the EPA_101, EPA_114, and NIST instruments decrease with increasing wavelength. The decrease in bandwidth with wavelength for the three instruments is 0.31 %/nm, 0.29 %/nm, and 0.18 %/nm, respectively.
The wavelength uncertainty is determined from the difference between the published values of the centroids for the particular model of Hg lamp (18) and the measured centroids. In general, the wavelength uncertainties were consistent between measurements of the various lamps. The deviations are larger for the NSF_SUV instrument, as explained below. The two Brewer instruments (EPA_101 and EPA_114) appear to have a distinct change in the centroid differences at 325 nm where the filter change occurs. After 325 nm, there is a systematic trend toward decreasing centroid differences with increasing wavelength. Possibly the original wavelength calibration for the Brewer instrument is not representative of the conversion from steps to wavelength and could be improved. In general, for the EPA_101 and EPA_114 instruments, the RMS (1) (Record Management Services) A file management system used in VAXs.
(2) (Root Mean Square) A method used to measure electrical output in volts and watts.
1. RMS - Record Management Services.
2. of the residuals of the centroid differences is 0.029 am and 0.027 nm, respectively.
The mean centroid offset for the NIST instrument is negligible This article or section is written like a personal reflection or and may require .
Please [ improve this article] by rewriting this article or section in an . (0.00014 nm) with a RMS of the residuals of the centroid differences of 0.0 12 nm, which is less than the 0.02 nm specification. The NSF_SUV instrument wavelength uncertainty results showed significantly larger scatter scat·ter
1. To cause to separate and go in different directions.
2. To separate and go in different directions; disperse.
3. To deflect radiation or particles.
n. than expected. The mean of the centroid differences for the NSF_SUV instrument using lines from the Hg, Zn lamps and HeCd laser is --0.06 am and the RMS of the residuals of the centroid differences is 0.12 nm. The mean centroid offsets for the Cd lines that were determined on a separate day and are not shown in Fig. 5.4 are consistently off by +0.3 am. These results for the NSF_SUV instrument are not indicative of the normal operation of the instrument and are a result of a programming error in the wavelength calibration routine that has subsequently been corrected. This wavelength uncertainty however did affect the results of the responsivity determination and the synchronized solar scans during the Intercomparison. See section 6. 4 for more details.
The mean centroid offset of the ASRC_RSS instrument is +0.013 nm with a RMS of 0.010 nm. The USDA_U1K instrument had a RMS of 0.007 am with an offset of +0.016 am. The centroid differences of the YES_RSS instrument had nearly zero offset (+0.007 nm) with a RMS of 0.011 am.
5.3 Spectral Irradiance Responsivity
Measuring the spectral irradiance responsivity (hereafter In the future.
The term hereafter is always used to indicate a future time—to the exclusion of both the past and present—in legal documents, statutes, and other similar papers. termed simply the responsivity) of the instruments with the NOAA standard lamps was the most important characterization performed at the Intercomparison. At the previous Intercomparisons, the responsivity was determined by the participant and by NIST and NOAA to show the agreement between the two spectral irradiance scales. However, at this Intercomparison the responsivity determined by the participants was not performed. This occurred primarily because many of the participants did not bring their own field calibration systems and previous Intercomparisons showed that its responsivity can change when an instrument is moved, highlighting the need for a field calibrator calibrator
an instrument for dilating a tubular structure or for determining the caliber of such a structure. to perform in-situ responsivity measurements as opposed to laboratory responsivity measurements prior to field placement (4). The responsivity was determined preferably pref·er·a·ble
More desirable or worthy than another; preferred: Coffee is preferable to tea, I think.
pref three times for each instrument to assess the temporal stability of the instruments and to use the most recent responsi vity of each instrument for the synchronized solar irradiance measurements.
As stated above, previous Intercomparisons showed that moving the instruments after calibrating caused measurable changes in the responsivity; therefore, this year the instruments were calibrated outdoors on the concrete pads where the instrument remained for the entirety The whole, in contradistinction to a moiety or part only. When land is conveyed to Husband and Wife, they do not take by moieties, but both are seised of the entirety. of the Intercomparison. The NOAA standard lamps were operated in the field calibration unit whose performance was demonstrated at the previous Intercomparison (5, 6). Experimental problems with the YES_RSS instrument had not been resolved during this stage of the Intercomparison and therefore its responsivity was not determined.
5.3.2 Experimental Procedure
Details of the NOAA field calibration unit are given in a separate paper (8). Briefly, the field calibration unit consists of three circular baffles, 45 cm in diameter and separated by 15 cm, with a mount for a horizontal lamp on the top baffle. A light trap above the lamp and shrouding shroud
1. A cloth used to wrap a body for burial; a winding sheet.
2. Something that conceals, protects, or screens: under a shroud of fog.
a. around the baffles enclose en·close also in·close
tr.v. en·closed, en·clos·ing, en·clos·es
1. To surround on all sides; close in.
2. To fence in so as to prevent common use: enclosed the pasture. the lamp, isolating i·so·late
tr.v. i·so·lat·ed, i·so·lat·ing, i·so·lates
1. To set apart or cut off from others.
2. To place in quarantine.
3. it from the surroundings, and the unit mounts on an interface plate, which is the key to the utility of the field calibration unit. Each instrument has an interface plate specifically designed to fit around the diffuser and rest on top of the instrument. The interface plate also sets the distance from the diffuser to the lamp at 50.0 cm by using spacers machined to the appropriate height. The lamp mount on the field calibration unit was adjusted once to center the lamp 50.0 cm above the diffuser.
The spectral irradiance of the 1000 W FEL-type NIST standard lamps, designated 96598 and 96599, had been determined by NOAA in the horizontal position using a method similar to the one described previously (19). The spectral irradiance of the 1000 W FEL-type NIST standard lamp, designated E-002, had been determined by NIST in the horizontal position also using the method described previously (19). The responsivity of each instrument was determined with the calibrated lamps mounted horizontally in the field calibration unit.
For all determinations of responsivity using a NIST or NOAA lamp, spectral scans were performed with a 3.5 cm wide shutter (1) An opaque window that is moved in one direction to let light in and in another to close off the light. In fixed-lens cameras, one shutter often suffices for aperture and speed. halfway between the lamp and the diffuser to measure the diffuse diffuse /dif·fuse/
1. (di-fus´) not definitely limited or localized.
2. (di-fuz´) to pass through or to spread widely through a tissue or substance.
adj. signal, and without the shutter to measure the total signal. For both Brewer instruments, the wavelength registration was set prior to measuring the responsivity. The EPA_101 and EPA_114 instruments performed spectral scans from 286.5 nm to 360 nm at 3.5 nm increments with increasing wavelength for both the diffuse and the total signal. Spectral scans with the NIST instrument were performed from 250 nm to 400 nm in 10 nm increments. Spectral scans with the NSF_SUV instrument were from either 270 nm or 250 nm to 400 nm with a PMT voltage of 800 V. These scans were at a 1.0 nm increment To add a number to another number. Incrementing a counter means adding 1 to its current value. with increasing wavelength with scans for the diffuse and total irradiance. In addition, scans were performed with the internal shutter closed to measure the dark signal. Both the diffuse and total signals from the SERC instrument were collect ed for nine minutes. The USDA UV-MFRSR instruments (USDA_270, USDA_386, USDA_387) measured diffuse and total signals for 10 minutes. The ASRC_RSS spectrograph collected signals from 295.7 to 349.0 nm at approximately every 0.08 nm for both the diffuse and total signals. The USDA_U1K instrument performed spectral scans from 280 nm to 410 nm at a 1 nm increment with increasing wavelength for the diffuse signal and for the total signal. A schedule of the spectral scans of standard lamps is given in Table 5.2, along with the corresponding instrument temperatures if available.
There were problems associated with using the adaptor An alternate spelling of "adapter." See adapter.
(tool) Adaptor - (Automatic DAta Parallelism TranslatOR) A source to source transformation tool that transforms data parallel programs written in Fortran 77 with array extensions, parallel loops, and layout directives to plates for the field calibration unit on the ASRC_RSS and USDA_U1K instruments. An incorrect fit of the adaptor plate to each of these instruments resulted in an increased uncertainty in the responsivity measurements due to alignment, as seen in Table 5.3.
5.3.3 Data Analysis
From spectral scans of a standard lamp, the responsivity is given by dividing the signal by the lamp irradiance. For the NIST and NOAA standard lamps, the signal was the direct signal, given by the difference between the total signal and the diffuse signal where the diffuse signal was determined by placing a shutter in front of the lamp during the irradiance measurement. Typically, the responsivity determined by the participants for use in their networks do not use a shutter to determine the diffuse signal and the signal is therefore the total signal. The spectral irradiance of the standard lamps was fit with a cubic spline interpolation In the mathematical field of numerical analysis, spline interpolation is a form of interpolation where the interpolant is a special type of piecewise polynomial called a spline. to the wavelengths of the signals. The NOAA standard lamps had been calibrated from 250 nm to 400 nm, which covers the wavelength range measured during this Intercomparison.
The uncertainty analysis for the responsivities is similar to the approach given in previous Intercomparisons (4, 6), where the details are presented in Appendix D of Ref. (5) and the specifics for each instrument are given in Appendix B here. Components of uncertainty arise from the standard lamp (spectral irradiance, size of diffuser, goniometric go·ni·om·e·ter
1. An optical instrument for measuring crystal angles, as between crystal faces.
2. A radio receiver and directional antenna used as a system to determine the angular direction of incoming radio signals. distribution, and current), the alignment of the lamp, and the instrument (wavelength and signal). The relative standard uncertainties arising from each component for both random and systematic uncertainties are given in Table 5.3 at selected wavelengths for the first determination of responsivity with the field calibration unit. The relative standard uncertainties are combined in quadrature quadrature, in astronomy, arrangement of two celestial bodies at right angles to each other as viewed from a reference point. If the reference point is the earth and the sun is one of the bodies, a planet is in quadrature when its elongation is 90°. for both random and systematic effects. The relative standard uncertainty in the relative difference between two responsivities determined by the NOAA standard lamp includes components of uncertainty arising only from random effects Random effects can refer to:
5.3.4 Results and Discussion
The responsivities of the instruments as a function of wavelength are shown in Fig. 5.5. The peaks in the responsivities of the EPA instruments between 300 nm and 320 nm are primarily due to the shape of the spectral response The variable output of a light-sensitive device that is based on the color of the light it perceives. of the [NiSO.sub.4] filters. The abrupt change in responsivity at 325 nm is due to a change from a [NiSO.sub.4]/UG-11 filter combination with the grating operating in second order for wavelengths at and shorter than 325 nm to a UG-11 filter with the grating also operating in second order for wavelengths longer than 325 nm. The responsivity of the ASRC_RSS, EPA_101, EPA_114, NIST, and SERC instruments are designed to peak at the shorter wavelengths where the solar irradiance signal is low and decrease at larger wavelengths where the solar irradiance signal is larger. The shape of the responsivity for the ASRC_RSS is largely controlled by the detector array sensitivity and the fore-optics throughput, the latter combining the solar blind filter transmittance and the transmittance of the fus ed silica silica or silicon dioxide, chemical compound, SiO2. It is insoluble in water, slightly soluble in alkalies, and soluble in dilute hydrofluoric acid. Pure silica is colorless to white. lens. The responsivity of the NIST, NSF_SUV, and USDA_U1K instruments are dominated by the fore-optics, monochromators, and PMT. The responsivity of the SERC instrument is dominated by the PMT.
Figure 5.5 gives all of the responsivities determined with the three NIST and NOAA lamps (NOAA#96598, NOAA-#96599, and NIST-#E002). The same data as in Fig. 5.5 is shown in Fig. 5.6 as the ratio of the responsivity on the day given in the legend to the initially determined responsivity using the NOAA and NIST standard lamps for each of the instruments. The temporal stability of the instrument is indicated in the difference between responsivities determined with the same lamp at two different times. The relative difference between the responsivity and the responsivity determined with the same lamp at a later date is given in Fig. 5.7. The vertical bars in Fig. 5.7 are the combined standard uncertainties of the differences using components arising from only random effects. The relative standard uncertainties from random and systematic effects are given in Table 5.3. It is valuable to differentiate systematic from random effects here because the uncertainties from random effects in the responsivity become syste matic effects in the uncertainty of the solar irradiance. All of the uncertainty components used a Type B evaluation except the instrument signal, which used a Type A evaluation. The total uncertainties in the responsivities when propagated to the solar irradiance contribute to the uncertainties in the solar irradiance measurements.
For the EPA_114 instrument, the responsivity was fairly stable and decreased by 2.7 % or less over the measured wavelength range from day 263 to day 266 with a mean decrease of 0.7 %. This stability is better than expected because the optics and the detector of the Brewer Mark IV instrument are not temperature stabilized and as a result the responsivity of the instrument is temperature dependent. Temperature measurements during the responsivity determination are given in Table 5.2. For the NIST instrument, the responsivities determined by the two lamps In the mythology of J. R. R. Tolkien's fictional Middle-earth, Illuin (Sky-blue) and Ormal (high gold) were great lamps which stood respectively at the northern and southern ends of Arda during the Years of the Lamps. (Fig. 5.6) differ by as much as 12 % at two different times on day 260. This result is primarily caused by electronic problems that began during the Intercomparison and was difficult to resolve outdoors in the rain.
The responsivity of the NSF_SUV instrument determined on day 261 with NOAA lamp #96599 differed by less than 0.7 % from the responsivity determined on day 261 with NOAA lamp #96598 with an average decrease of -0.17 % from the #96599 scan to the #96598 scan. The responsivities determined on day 263 and day 268 are very consistent with each other and agree within 1.8% regardless of which lamp is used. There is a distinct increase in the responsivity from day 261 to the responsivities determined after this day of up to 5% at 280 nm. This change is most likely due to a combination of an error in a wavelength calibration program, which will be discussed further in Sec. 6.4, and a drift drift, deposit of mixed clay, gravel, sand, and boulders transported and laid down by glaciers. Stratified, or glaciofluvial, drift is carried by waters flowing from the melting ice of a glacier. in the instrument. The internal lamp scans show a drift in the instrument of not more than 2% over 9 days and is illustrated in Fig. 5.8, which gives the relative difference in responsivity determined with the internal lamp with each succeeding day from the responsivity determined on day 259. Disregarding dis·re·gard
tr.v. dis·re·gard·ed, dis·re·gard·ing, dis·re·gards
1. To pay no attention or heed to; ignore.
2. To treat without proper respect or attentiveness.
n. the wavelength programming error, the NSF_SUV instrument shows very good temporal stability.
The responsivity of the ASRC_RSS instrument shows significant scatter ([+ or -]10%) from one determination to the next but negligible offset (Fig. 5.6). The relatively large scatter of data points can be explained by low sensitivity of the MOS detector array and low lamp irradiance below 310 nm, and then low signal above 330 nm due to the intentionally low throughput of the fore-optics, as shown in Figure 5.5. Consequently, the relative standard uncertainty of the responsivity measurement at 295 nm is 5.2% and at 348.8 nm is 14.8%, which is consistent with Figure 5.6. The responsivity of the USDA_U1K instrument determined using lamp #96598 decreased by a mean of 0.4% from Julian day 261 to 264 as shown in Figure 5.7 and is within 1.8% for all but two points. As illustrated in Fig. 5.6 the responsivity determined on day 266 decreased by a mean of 2.6 % from day 261 but used a different lamp. The largest sources of uncertainties in the USDA_UlK signal are the random component from the signal and the uncertaint y in the positioning of the standard NOAA lamp over the instrument. The uncertainty components are given in Table 5.3.
There were three UV-MFRSR instruments at the Intercomparison with serial numbers #270, #386, and #387 and the temporal stability of all three instruments were similar. The three instruments showed an approximate mean decrease of 1.2 %, 0.6 %, and 0.9 % over 7 d, 2 d, and 3 d (Fig. 5.7), respectively. The 311 nm channel of the USDA_270 showed a decrease of 5 % over the 8 days that was unexplained unexplained
strange or unclear because the reason for it is not known
Adj. 1. unexplained - not explained; "accomplished by some unexplained process" . This instrument shows pronounced deviations from day 261 to day 263 (Fig. 5.6) but this was attributed to insufficient warm-up warm-up
pre-race exercise by a horse. time of the head and was not an indication of the instrument's stability. The typical warm-up time of the head of an UV-MFRSR prior to measurement of the responsivity should be at least 20 mm. Excluding the responsivity determined with an insufficient warm-up time, all three instruments showed changes in the responsivity within 5 %. The responsivity of the SERC instrument decreased by less than 4.4 % over the wavelength range and had a mean decrease in the responsivity of 3.5 % from day 262 to day 263 which is consistent with previous Intercomparisons. The responsivity of the SERC instrument decreased by less than 2.9 % from day 261 to day 267.
The conclusions to be drawn from the determinations of responsivity are similar to those from the previous Intercomparisons. The responsivity changes were within [+ or -]5 % indicating relatively good temporal stability. Unlike the results in 1994, the temperature changes between determinations of responsivity for the EPA instruments were not sufficient to illustrate the effect of temperature on responsivity. The responsivities determined outdoors using the NOAA standard lamp were used to calculate the irradiance from the synchronized solar scans. Using a common standard for responsivity simplifies intercomparisons between measured irradiance since differences between spectral irradiance scales are removed from the analysis. Therefore, actual instrument performances can be evaluated more readily. Whether the optics or the detector of the instruments are temperature stabilized is indicated in Table 3.1.
6. Solar Irradiance
The major goal of the Intercomparison was to have all the instruments measure the solar ultraviolet irradiance concurrently, which was achieved over several days of the Intercomparison. The solar ultraviolet irradiance E([[lambda].sub.0]) was calculated from the measured signals S([[lambda].sub.0]) using the simplified measurement equation given by
E([[lambda].sub.0]) = S([[lambda].sub.0])/R([[lambda].sub.0]), (6.1)
where R ([[lambda].sub.0]) is the responsivity for each instrument. This was done to provide a common irradiance scale for all the instruments, thereby removing discrepancies caused by different scales and facilitating comparisons between instruments. Several instruments were having operational problems during the Intercomparison and the unfavorable weather conditions made diagnosing and fixing the problems a daunting daunt
tr.v. daunt·ed, daunt·ing, daunts
To abate the courage of; discourage. See Synonyms at dismay.
[Middle English daunten, from Old French danter, from Latin task. These instruments included the YES UV-RSS spectrograph, which was having operational difficulties from the start of the Intercomparison, and the NIST instrument, which began to have electronic problems at a later stage of the Intercomparison. Neither of these instruments participated in the synchronized solar scans.
6.2 Experimental Procedure
Synchronized spectral measurements of the solar ultraviolet irradiance began on the hour and half-hour from wavelengths of 290 nm to 348 am at increments of 0.2 nm with 3 s between each wavelength. This range was common to all the instruments; the two EPA instruments, the NSF_SUV, and USDA_UlK instruments extended their scans to 363 am, 400 am, and 360 am, respectively. The clock for each instrument was set daily from a common clock synchronized with the satellite Global Positioning System Global Positioning System: see navigation satellite.
Global Positioning System (GPS)
Precise satellite-based navigation and location system originally developed for U.S. military use. . The scanning time for the synchronized scans from 290 nm to 360 nm was 17.5 min. The ASRC_RSS instrument is a spectrograph and therefore measures all wavelengths at once. To compare the ASRC_RSS to other scanning spectroradiometers, the wavelength measured at the particular scan time was chosen for synchronized comparisons, as explained in the instrument description section. Other measurements, such as wavelength calibrations and total column ozone, were performed by the two EPA Brewer instruments during the times between synchronized scans. The days, times, and participating instruments for the synchronized solar scans used in the analyses below are listed in Table 6.1. As stated above, both the YES_RSS instrument and the NIST instrument were not operational during the synchronized scans. The EPA_101 instrument was not operating correctly until after 15.0 h UTC on day 267 due to a power supply problem. The EPA_114 instrument had a jammed filter wheel until the morning of day 265, eliminating the earlier data from the analysis.
6.3 Data Analysis
For all instruments, the measured signal was corrected before the irradiance was calculated. For the two EPA instruments, the signal was converted to a photon rate (4) with dark subtraction and dead-time correction. Dark subtraction was performed on the NSF_SUV instrument by averaging all the signals at wavelengths shorter than 290 nm and subtracting this value from all the signals of the scan. Dark subtraction and averaging the signals over the 17.5 mi of the synchronized scans was performed for the SERC instrument. The average of the dark signals obtained immediately before and after a synchronized scan of the USDA_U1K instrument was subtracted from all the signals of the scan. For the ASRC_RSS instrument, the exposure time of the CCD array was set for 10 s with the shutter open to measure the total irradiance signal, and then the exposure was set for 10 s while the shutter was closed to measure the dark signal. The dark signal was then subtracted from the total signal.
The stray-light rejection of the instruments, shown in Fig. 5.2, can result in relatively large signals at the shortest wavelengths. To account for this, stray-light subtraction was employed for the EPA instruments. The signals at wavelengths shorter than 292 nm were averaged and subtracted from all signals from the scan. It was these signals with the stray-light subtraction that were divided by the responsivity to obtain the solar ultraviolet irradiance. The subtraction used for the NSF_SUV instrument would also correct for stray-light if it exists. The stray-light rejection of the USDA_U1K instrument was sufficient and no correction to the signals at the shortest wavelengths was necessary.
The method used to determine the responsivity of the NSF_SVU SVU Special Victims Unit
SVU Southern Virginia University (Buena Vista, Virginia)
SVU Society for Vascular Ultrasound
SVU Sri Venkateswara University (Tirupati, India)
SVU Syrian Virtual University instrument during solar scans complicated the data analysis. The usual procedure with this instrument is to transfer the spectral irradiance scale of the external 200 W lamp to the internal 45 W lamp from spectral scans of both lamps with the same high voltage on the PMT. Different high voltages are used for scans of the solar irradiance, and the responsivity of the instrument is dependent upon the high voltage. Therefore, the internal lamp is scanned at least daily at all PMT high voltages that are used for solar measurements. To use the NIST irradiance scale with this procedure, the scale was transferred to the NSF external 200 W lamp from the scan of the NIST standard lamp at 800 V, and this new scale for the external lamp was then used with scans of the internal 45 W lamp. The responsivity of the instrument at any high voltage was determined from the scan of the 45 W lamp at the same high voltage that occurred closest in time to the scan of the solar irradiance. To maintain consistency with the NSF_SUV procedure for responsivity, the responsivities used to calculate the solar irradiance were those determined closest in time to the synchronized scans.
The responsivities of the EPA instruments were determined every 3.5 nm while the solar irradiance scans are determined every 0.2 nm. Because of the filter change out after 325 nm, the responsivities were extrapolated from 328.5 nm to 325.01 am and from 360 nm to 363 nm using second-order polynomials. The extrapolation (mathematics, algorithm) extrapolation - A mathematical procedure which estimates values of a function for certain desired inputs given values for known inputs.
If the desired input is outside the range of the known values this is called extrapolation, if it is inside then for the responsivity of the EPA instrument does cause some additional uncertainties around 325.0 nm for this analysis that are then propagated in the solar irradiance scans. Typically, the EPA Network determines the responsivity at the same wavelengths as the solar irradiance scans and this is therefore not a problem. From Eq. (6.1), the irradiance at a given wavelength is the signal at that wavelength divided by the responsivity at that same wavelength; because the responsivities of the EPA instrument were not determined at all the wavelengths of the synchronized solar scans, the responsivities at these wavelengths were calculated from natural cubic spline interpolations. The days and times of the responsivities for the solar irradiance used by all participating instruments on day 267 are given in Table 6.2.
6.4 Results and Discussion
The solar irradiance as a function of wavelength determined by the scanning spectroradiometers and spectrograph instruments from a synchronized spectral scan on day 267 at 20h, 21.5h, and 23.5h UTC is shown in Fig. 6.1. Day 267 is chosen for the remainder of the comparisons because it is the only day that most instruments were operational and was also a clear sky day. The irradiance is plotted on a linear scale in Fig. 6.1(a,c,e) and on a logarithmic scale Noun 1. logarithmic scale - scale on which actual distances from the origin are proportional to the logarithms of the corresponding scale numbers
graduated table, ordered series, scale, scale of measurement - an ordered reference standard; "judging on a scale of 1 in Fig. 6. l(b,d,f). This figure illustrates the challenges encountered in accurately measuring the solar ultraviolet irradiance, especially in the UV-B wavelength region, and of comparing the results between instruments. The outstanding feature of ground-level solar ultraviolet irradiance is its rapid decrease with decreasing wavelength in the UV-B region due to absorption by ozone, as illustrated in Fig. 6.1(b,d,f). The irradiance decreases by five to six orders of magnitude from 325 nm to 290 nm, which imposes stringent requirements on the instruments in terms of wavelength accuracy and stray-light rejection (see Sec. 5). In the region of steepest decrease, a relatively small uncertainty in wavelength translates into a large uncertainty in irradiance. An accurate measurement of the irradiance at the shortest wavelengths requires the best possible stray-light rejection so the signal is not dominated by light from wavelengths longer than the nominal one.
The moderately structured nature of the solar spectral irradiance, as shown in Fig. 6.1(a,c,e) for wavelengths greater than 310 nm, complicates comparisons between instruments. While the structure of the spectral irradiance is consistent among instruments, with maxima and minima occurring at approximately the same wavelengths, the effect of the different bandwidths is also apparent. As the bandwidths of the instruments increase from USDA_U1K, ASRC_RSS, EPA, to NSF_SUV the measured spectral irradiance becomes smoother. The maxima and minima measured by the USDA_UlK instrument are more pronounced than those measured by the EPA instruments, for instance, and virtually no structure is evident with the filter instruments (SERC, UVMFRSR). The solar irradiance plotted on a logarithmic scale gives an indicator of which instruments are capable of measuring below 300 nm.
The problem remains of how to compare the solar irradiance measured by instruments with different bandwidths. While deconvolution In mathematics, deconvolution is an algorithm-based process used to reverse the effects of convolution on recorded data. The concept of deconvolution is widely used in the techniques of signal processing and image processing. and spectral synthesis techniques are being investigated, for convenience the approach taken for this paper is to convolve con·volve
v. con·volved, con·volv·ing, con·volves
To roll together; coil up.
To form convolutions. the irradiance with a common slit-scattering function (20, 21). This assumes the instruments are accurately measuring the solar irradiance, so that the convolution is approximating the solar irradiance that would be obtained by a hypothetical Hypothetical is an adjective, meaning of or pertaining to a hypothesis. See:
The study of the propagation of energy by radiative processes; it is also called radiation transport. Radiation is one of the three mechanisms by which energy moves from one place to another, the other two being conduction and convection. . The irradiance [E.sub.j] at filter channel j for each scanning instrument is given by
[E.sub.j] = [summation over (i)]E([[lambda].sub.i])[[tau].sub.j]([[lambda].sub.i])/[summation over (i)][[tau].sub.j]([[lambda].sub.i]), (6.2)
where i indexes the wavelengths [[lambda].sub.i] and [[tau].sub.j] is the filter transmittance for channel j.
The relative standard deviation is the quantity used to quantify Quantify - A performance analysis tool from Pure Software. the agreement between instruments and is the standard deviation of the solar irradiance divided by the average irradiance at each wavelength. The relative difference is also used to convey the spread of values and is a good indicator of each instrument's performance. The relative difference is given by the solar irradiance measured by a particular instrument minus the average of the solar irradiance divided by the average solar irradiance at each wavelength. Because all the instruments performed synchronized spectral scans under nominally identical conditions, they are assumed to have been exposed to the same spectral irradiance. However, each instrument measured an independent value for the solar irradiance, and therefore the relative difference of these independent values is used to indicate the agreement between instruments.
The results presented here focus on the irradiance measured on day 267 at 16.5 h UTC since all the instruments were operating correctly and the sky was clear. The relative difference of the solar irradiance convolved with a 1 nm triangular slit-function for the instrument given in the legend to the average solar irradiance of all the instruments given in the legend is shown in Fig. 6.2 a-c. The relative differences in Fig. 6.2 a use the triangular convolution and range from -8 % to 25 % for wavelengths greater than 305 nm. This is greater than expected from the propagation of uncertainties In statistics, propagation of uncertainty (or propagation of error) is the effect of variables' uncertainties (or errors) on the uncertainty of a function based on them. . The NSF_SUV instrument is noticeably no·tice·a·ble
1. Evident; observable: noticeable changes in temperature; a noticeable lack of friendliness.
2. Worthy of notice; significant. higher than the other spectroradiometers and also shows significant spectral structure (Fig. 6.2 a). The significant spectral structure for the NSF_SUV data in Fig. 6.2 a suggests a wavelength calibration problem. A spectral shift of the data of approximately 0.3 nm corrects the discrepancy DISCREPANCY. A difference between one thing and another, between one writing and another; a variance. (q.v.)
2. Discrepancies are material and immaterial. . A further analysis revealed a programming error in a wavelength calibration routine used by the NSF_SUV instrument. This program is not generally used in routine remote operations but was used as an additional check. The program is designed to determine the position of the 253.652 nm Hg line in measured wavelength scans, subtract A relational DBMS operation that generates a third file from all the records in one file that are not in a second file. this position from the nominal value of 253.652 nm and adjust the wavelength calibration of the instrument by this difference. Unfortunately, the measured position was stored as an integer integer: see number; number theory , i.e., 254 nm. During several occasions, including day 267, the wavelength calibration was incorrectly adjusted by the difference of 254 and 253.652, which resulted in a wavelength error of 0.348 nm for day 267. The corrected NSF_SUV solar irradiance data are plotted in Fig. 6.2 b and and show a significant improvement in the agreement with the other instruments. The wavelength calibration was also checked and recomputed for the responsivity measurements. With the corrected NSF_SUV solar irradiance data, the spectral structure has been reduced and the overall agreement with the other instrume nts has increased. In Fig. 6.2 b, the relative difference has decreased to a range from [+ or -]6 % for wavelengths greater than 305 um using the corrected NSF_SUV solar irradiance data.
In contrast, convolving with a Gaussian slit-scattering function results in relative differences that range from [+ or -]5 % and are approximately the same as those expected from the propagation of uncertainties. Here, the minima and maxima have decreased from the triangular convolution in Fig. 6.2 b. The decreased relative differences relative to those obtained with a triangular convolution are primarily a result of convolving with a function which includes all the wavelengths from the spectral scan, and not a limited number as with the triangular convolution. However, convolving with a Gaussian function In mathematics, a Gaussian function (named after Carl Friedrich Gauss) is a function of the form:
for some real constants a > 0, b, and c. is a reasonable method for comparing irradiance measured by instruments with different bandwidths since all the convolved irradiances include the bandwidths of all the instruments. The discrepancies between instruments increase significantly below 300 nm and are in part due to differences in stray-light rejection (see Sec. 5.1). An instrument with poor stray-light rejection is expected to have a larger sign al than the true value. Because the USDA_U1K instrument was shown to have the best stray-light rejection ([approximately equal to] [10.sup.-10]), the percent relative difference is plotted relative to the USDA_U1K solar irradiance data (Fig. 6.2 d). The ASRC_RSS instrument is showing unusual behavior starting around 303 am, becoming more pronounced as the day progressed; this feature is unexplained. Excluding the data from the ASRC_RSS instrument, the USDA_U1K instrument has the lowest irradiance at the shorter wavelengths and the NSF_SUV instrument, which is also a double monochromator, measures less than the Brewer spectroradiometers at these shorter wavelengths.
The relative standard deviations of the solar irradiances measured by the five instruments from Figs. 6.2 b and 6.2 c are shown in Fig. 6.3. For the triangle slit scattering function the relative standard deviation is less than 5 % for wavelengths longer than 305 nm (Fig. 6.3 a) and for the Gaussian slit scattering function the relative standard deviation is less than 4 % (Fig. 6.3 b). In general, the convolution removes most of the discrepancies due to differences in bandwidth. The differences in bandwidth and the wavelength uncertainties among the instruments are responsible for much of the spectral structure observed in the relative differences. Using the same analysis used previously (4) and assuming a 2 % relative standard deviation from all other sources, a wavelength uncertainty of approximately 0.1 nm would account for the relative differences in Fig. 6.2 d.
Figure 6.4 illustrates the relative differences between instruments with changing solar zenith angle Zenith Angle can refer to:
SZA Surf-Zone Array
SZA Safety Zone Area ). Figure 6.4 gives the solar irradiance convolved with Gaussian slit-scattering function versus wavelength for the instruments indicated in the legend for four different times indicated in the title (16 h, 20 h, 21.5 h, and 23.5 h UTC or 56.4[degrees], 43.2[degrees], 54[degrees] and 74.5[degrees] SZA). The relative differences generally increase with increasing solar zenith angle, partly due to the increased uncertainties in the measurements, but also due to differences between the instruments. This could possibly be due to either the differences in the angular response of the detectors or the linearity of the detectors. Interestingly, the EPA instruments are grouped together and decrease relative to the USDA_U1K, ASRC_RSS, and the NSF_SUV as the solar zenith angle increases. This is consistent with their angular response because the angular response of the USDA_U1K, ASRC_RSS and the NSF_SUV instrument ar e in general closer to ideal than the two EPA instruments. Instruments with a non-ideal angular response measure less irradiance than the true irradiance and as the solar zenith angle increases the angular response error typically increases. For instance, the Brewer instruments are estimated to measure approximately 3 % low at high sun and 8 % low at low sun due to angular response error based on a typical measured angular response and model calculations of the sky radiance on a clear sky day, but of course these estimates depend on the specific sky conditions (22). The angular responses of all the instruments were not available at the time of this analysis, but it would be useful in the future to apply the angular corrections to the solar irradiance data of each instrument and observe if this improves the agreement between irradiance measured by the instruments. As the day progresses, the ASRC_RSS instrument is measuring significantly more than the other instruments at the shorter wavelengths and is outside the uncertainty limits. It is unclear what is causing this because the effect is not seen at similar zenith angles earlier in the day. it is usually instructive in·struc·tive
Conveying knowledge or information; enlightening.
in·structive·ly adv. to compare the irradiance measured by each instrument on different days. This is usually done to assess how the different instruments respond to changing ozone conditions and changing cloud cover relative to one another. However, because of poor weather, instrumental difficulties, and a short-term Short-term
Any investments with a maturity of one year or less.
1. Of or relating to a gain or loss on the value of an asset that has been held less than a specified period of time. power outage Noun 1. power outage - equipment failure resulting when the supply of power fails; "the ice storm caused a power outage"
equipment failure, breakdown - a cessation of normal operation; "there was a power breakdown" , there were no other days where all the instruments were operating to do this comparison.
In the final comparison, the solar irradiance of the scanning spectroradiometers and spectrographs are convolved with the filter transmittances of the SERC and each of the three UVMFRSR's, and are compared to the solar irradiance measurements from each of the filter instruments (SERC, UVMFRSR_270, UVMFRSR_386, UVMFRSR_387). Figure 6.5 plots the solar irradiance as a function of wavelength for day 267 h and 16.5 h UTC for the four filter instruments and Fig. 6.6 plots the relative difference to the average. The important point in these figures is how the solar irradiance from the filter instrument (the stars) compares to the convolved spectroradiometer data. Figure 6.6 a compares the solar irradiance from each of the spectroradiometers convolved with the SERC filter transmittances and the SERC solar irradiance data. The SERC instrument agrees within 8 % to the filter-weighted spectral irradiance data for all filters except the four shortest filter wavelengths (<296 nm nominal wavelength). Certainly, many of t he spectral instruments have difficulty measuring the shorter UV wavelengths and comparing to the average at these wavelengths is not too informative. The SERC channels 294 nm and 296 nm agree within 10 % to the USDA_UlK instrument; however, the two shortest wavelength SERC channels (not shown) are over 90 % higher than the USDA_UlK which has the best stray-light rejection. The comparisons at other solar zenith angles are similar. Figure 6.6 b-d compares the solar irradiance from the spectral instruments convolved with each of the UVMFRSR filter functions (USDA_270, USDA_386, USDA_387) for day 267 at 16.5 h UTC. The 368 nm UVMFRSR channel is not compared to the spectral instruments because the Intercomparison format did not extend out to this wavelength in order to obtain synchronous scans that start on the half hour. The agreement for all three UVMFRSR radiometers with the spectral instruments convolved with the UVMFRSR filter functions is within 7 % except for channel 1 (300 nm nominal wavelength) for USDA_ 386 and USDA_387. Channel 1 for the USDA_270 instrument agrees with the average within 1 %, but the USDA_386 and USDA_387 instruments are approximately 20 % lower than the average. The filter functions were not determined at the Intercomparison or at the CUCF and possibly the filter transmittances for these channels have changed since their measurement. Ideally, for future Intercomparisons, the filter functions should be determined just prior to the Intercomparison and compared with the previous measurements.
Finally, the relative standard deviation for the ASRC_RSS, EPA_101, EPA_114, NSF_SUV USDA_UlK and SERC instruments convolved with a SERC filter function is less than 4 % for filters greater than 300 nm (Fig. 6.7 a). The relative standard deviations for the ASRC_RSS, EPA_101, EPA_114, NSF_SUV USDA_UlK and UVMFRSR instruments convolved with the filter functions of the three UVMFRSR instruments, and then compared with these three instruments, is less than 4 % for wavelengths greater than 300 nm (Fig. 6.7 b-d).
Several prototype and relatively new instruments participated in the 1997 Intercomparison and showed very promising results. The double monochromators of the USDA_U1K and the NSF_SUV instruments and the dual prism of the ASRC_RSS instrument are used to improve stray-light rejection, which can be a significant problem at the shorter UV wavelengths where ozone absorption is the strongest. Accurately measuring solar irradiance at the shorter wavelengths is very desirable because changes in atmospheric ozone concentrations will have a larger impact on the solar irradiance, possibly decreasing the time frame needed for detection of trends. It should be mentioned that the Intercomparison format did not show all the benefits of each instrument.
For instance, the ASRC_RSS and the YES_RSS spectrograph instruments, and the UVMFRSRs are capable of measuring all wavelengths simultaneously, and the SERC instrument performs a scan every 4.3 s, which is desirable when investigating a rapidly changing atmosphere such as cloud effects on solar irradiance. These same instruments except the SERC are also rotating shadowband radiometers that are capable of measuring the total irradiance and the diffuse beam, and consequently the direct beam from subtraction. The NSF_SUV instrument is capable of measuring irradiance out to 600 nm, which is useful for many applications in atmospheric research Atmospheric Research (ISSN 0169-8095) is scientific journal dealing with the part of the atmosphere where meteorological events occur; intended for atmospheric scientists (such as meteorologists and climatologists), aerosol scientists, and hydrologists. .
As in previous years, the 1997 Intercomparison characterized instruments for stray-light, bandwidth, and wavelength accuracy using spectral lines spectral line
An isolated bright or dark line in a spectrum produced by emission or absorption of light of a single wavelength.
spectral line from a HeCd laser, and Hg, Cd, and Zn lamps. These results are summarized in Table 5.1. The stray-light rejections of the instruments were consistent with those expected for single- and double-grating monochromators and for interference filters. The bandwidths of the EPA_101, EPA_114, and the NIST scanning instruments decreased with increasing wavelength. The bandwidth of the spectrograph instruments, ASRC_RSS and YES_RSS, increased with increasing wavelength. The bandwidth of the NSF_SUV and the USDA_U1K remained relatively constant with wavelength. Many of the newer instruments, ASRC_RSS NIST, USDA_U1K, and YES_RSS, showed very good wavelength accuracy of better than 0.02 nm. For the EPA instruments, the wavelength uncertainties showed some dependence on wavelength. The wavelength accuracy of the NSF_SUV instrument was less than expected but this is attributable t o an error in a wavelength calibration routine that has subsequently been remedied.
The spectral irradiance responsivity of the instruments was determined several times outdoors with the NOAA horizontally calibrated 1000 W lamps using the NOAA field calibrator. The temporal stability of the responsivities is very important for reliability of spectral solar irradiance measurements and should change as little as possible while the instruments are monitoring solar ultraviolet irradiance. There was not sufficient data to completely assess the temporal stability of the instruments under a variety of conditions but the responsivity was determined several times to get an indication of the stability. In this current set of spectroradiometers, the responsivities do not change more than 5 % over 5 days except for the NIST instrument, which had electronic problems related to the weather because the instrument was not weatherproof, and the UVMFRSR_270 which may have had an insufficient warm-up time prior to the measurement. The responsivity of the ASRC_RSS instrument had a negligible offset from one sca n to the next but scatter of approximately 10 % at the short and long wavelengths, which is attributed to the low sensitivity of the MOS detector.
Synchronized solar irradiance scans from 290 nm to 360 nm were performed every half-hour during the Intercomparison. Because the instruments had different bandwidths, the measured irradiances were convolved to common bandwidths by using both triangular and Gaussian slit scattering functions and the filter transmittances of the filter-based instruments. The agreement among the convolved irradiances was described by their relative difference from the average. The relative standard deviation in the solar irradiance convolved with a triangular slit-scattering function between the spectral instruments was within 5 % using the corrected NSF_SUV data for wavelengths greater than 300 nm on day 267 at 16.5 h UTC. With the Gaussian slit-scattering function the relative standard deviation was within 4 %. The ASRC_RSS instrument deviates from the average more than expected for 300 nm to 305 nm and the problem becomes more severe as the day progresses. The changes in the relative differences of the spectral instruments wi th increasing solar zenith angle indicates a possible difference in the angular responses of the instruments, suggesting the need for corrections or improvements in the Lambertian quality of the diffusers and linearity of the detectors. The relative standard deviation of the solar irradiance at 16.5 h UTC including the filter instruments was 4 % for wavelengths above 300 nm. The solar irradiances for filter wavelengths down to 296 nm agree within 10 % to those of the USDA_U1K instrument on day 267 at 16.5 h UTC.
In conclusion, this Intercomparison was successful at characterizing the instruments and comparing the newer instruments with existing UV spectroradiometers. Even with difficult weather, all the instrument characterizations could be performed outdoors. The results from the data yielded valuable information about the performance of the instruments, especially the prototype instruments, and suggested possible improvements in techniques and design.
8. Appendix A. Attendees
The following people attended the 1997 North American Interagency Intercomparison of Ultraviolet Monitoring Spectroradiometers, and are grouped by function and network.
National Oceanic and Atmospheric Administration (NOAA)
John DeLuisi (303) 497-6083 firstname.lastname@example.org
Kathleen Lantz (303) 497-7280 email@example.com
Patrick Disterhoft (303) 497-6355 firstname.lastname@example.org
Fax (303) 497-6546
Boulder, CO 80303
National Institute of Standards and Technology (NIST)
Ted Early (301) 975-2343 email@example.com
Fax (301) 840-8551
Bldg. 220, Rm. A-320
Gaithersburg, MD 20899-0001
National Institute of Standards and Technology (NIST)
Ambler Thompson Thompson, city, Canada
Thompson, city (1991 pop. 14,977), central Man., Canada, on the Burntwood River. A mining town, it developed after large nickel deposits were discovered in the area in 1956. (301) 975-2333 firstname.lastname@example.org
Fax (301) 840-8551
Gaithersburg, MD 20899-0001
Environmental Protection Agency Environmental Protection Agency (EPA), independent agency of the U.S. government, with headquarters in Washington, D.C. It was established in 1970 to reduce and control air and water pollution, noise pollution, and radiation and to ensure the safe handling and (EPA)
Thomas Taylor Thomas Taylor could refer to:
Fax (706) 542-2492
NUVMC/University of Georgia Georgia, country, Asia
Georgia (jôr`jə), Georgian Sakartvelo, Rus. Gruziya, officially Republic of Georgia, republic (2005 est. pop. 4,677,000), c.26,900 sq mi (69,700 sq km), in W Transcaucasia.
Dept. of Physics and Astronomy astronomy, branch of science that studies the motions and natures of celestial bodies, such as planets, stars, and galaxies; more generally, the study of matter and energy in the universe at large.
University of Georgia
Athens, GA 30602
National Science Foundation (NSF)
James Ehramjian (619) 686-1888 email@example.com
Laura Cabasag (619) 686-1888 firstname.lastname@example.org
James Robertson James Robertson may refer to:
Germar Bernhard (619) 686-1888 email@example.com
Fax (619) 686-1887
Biospherical Instruments, Inc.
5340 Riley Street
San Diego San Diego (săn dēā`gō), city (1990 pop. 1,110,549), seat of San Diego co., S Calif., on San Diego Bay; inc. 1850. San Diego includes the unincorporated communities of La Jolla and Spring Valley. Coronado is across the bay. , CA 92110-2621
Smithsonian Environmental Research Center (SERC)
Fax (301) 261-7954
Smithsonian Environmental Research Center
P.O. Box 28
Edgewater, MD 21037
United States Department of Agriculture United States Department of Agriculture (USDA),
n.pr established in 1862, USDA is responsible for the safety of meat, poultry, and egg products. It conducts ongoing research in areas from human nutrition to new crop technologies and also helps ensure open (USDA)
Lee Harrison Lee Harrison (born 12 September 1971 in Billericay) is an English footballer. He has played in over 400 League and Cup games for Gillingham, Fulham, Barnet, Leyton Orient and Peterborough United. (518) 437-8741 firstname.lastname@example.org
Jerry Berndt Jerry Berndt was a college football coach at Penn, Rice, and Temple. From 1981 to 1985, he coached at Penn, and compiled a 29-18-2 record. In 1984, he posted a 15 game winning streak, giving him Ivy League Coach of the Year honors. (518) 437-8738 email@example.com
Peter Kiedron (518) 437-8737 firstname.lastname@example.org
Fax (518) 437-8758
Atmospheric Sciences Research Center
State University of New York at Albany
251 Fuller Road
Albany, NY 12205
United States Department of Agriculture (USDA)
James Slusser (970) 491-3623 email@example.com
David Bigelow: contact James Slusser
Bill Durham (970) 491-3604 firstname.lastname@example.org
George Janson (970) 491-3621 email@example.com
Natural Resource Ecology Laboratory
Colorado State University
Fort Collins, CO 90523
Yankee Environmental Systems, Inc. (YES_RSS)
Arthur Beaubien (413) 863-0200 firstname.lastname@example.org
Mark Beaubien (413) 863-0200 email@example.com
Airport Industrial Park
Turner Falls Turner Falls is Oklahoma's tallest waterfall, measuring some 77 feet in its full descent, and continually rates as one of Oklahoma's most popular attractions, drawing thousands from the region in the sweltering days of summer. , MA 01376
9. Appendix B. Responsivity Uncertainty Analysis
A general description of the uncertainty analysis has been given previously (5). The following is the specific information used to determine the uncertainties in the responsivity measurement for the prototype instruments. The specific information on instruments that had attended previous Intercomparisons is given in Ref. (5). The sizes of the diffusers are parameters for the uncertainties arising from both the distribution of flux flux
In metallurgy, any substance introduced in the smelting of ores to promote fluidity and to remove objectionable impurities in the form of slag. Limestone is commonly used for this purpose in smelting iron ores. over the diffuser and the goniometric distribution of flux from the lamp (g). The radii ra·di·i
A plural of radius.
a plural of radius of the diffusers of the instruments are given in Table B.1. For the goniometric distribution, [g.sub.avg] = 0.995 was assumed for both lamps, and the distance D = 50 cm.
The quadrature sum of the standard uncertainty in lamp current arising from random effects is 0.42 mA. The quadrature sum of the standard uncertainty in current arising from systematic effects is 0.81 mA. For the lamp goniometric distribution, [g.sub.max] = 0.01 was assumed for both lamps. The uncertainty in the retro-reflected position of the laser beam from the lamp jig jig, dance of English origin that is performed also in Ireland and Scotland. It is usually a lively dance, performed by one or more persons, with quick and irregular steps. When the jig was introduced to the United States, it was often danced in minstrel shows. was 0.2 cm, the positioning uncertainty in centering the beam on the diffuser was 0.1 cm for the EPA instruments, the SERC, UV-MFRSRs and NIST instruments and 0.2 cm for the others. The uncertainty in centering the beam on the lamp jig was 0.16 cm for the EPA instruments, NIST, NSF_SUV, the UV-MFRSRs, and SERC and 1.0 for the others. The uncertainty in the distance between the diffuser and the lamp jig was 0.2 cm for the ASRC_RSS, USDA_U1K, and YES_RSS and 0.1 cm for the others. When the field calibration unit was used to mount the lamp, the uncertainty in aligning a·lign
v. a·ligned, a·lign·ing, a·ligns
1. To arrange in a line or so as to be parallel: align the tops of a row of pictures; aligned the car with the curb. the lamp jig perpendicular to the optic axis optic axis
The line connecting the anterior and the posterior poles of the eye. was 0.5[degrees], the uncertain ty in centering the lamp jig was 0.1 cm, and the uncertainty in the distance between the lamp jig and the diffuser was 0.1 cm.
The uncertainty in wavelength was determined by fitting the centroid differences shown in Fig. 5.4 with a second order polynomial polynomial, mathematical expression which is a finite sum, each term being a constant times a product of one or more variables raised to powers. With only one variable the general form of a polynomial is a0xn+a . The fit is appropriate for the given wavelength range. The wavelength uncertainty for the SERC instrument was determined during the 1995 Intercomparison (5). The coefficients for the second order polynomial fits are given in Table B.2.
Table B.1 Diffuser Radii Instrument Radius (cm) EPA_101 1.6 EPA_114 1.6 NIST 1.27 NSF_SUV 1.05 SERC 0.95 USDA_270,386,387 0.4 ASRC_RSS 0.4 USDA_U1K 1.27 YES_RSS 0.4 Table B.2. Wavelength uncertainties Instrument Wavelength range (nm) Coefficient, [c.sub.0] EPA_101 290 to 350 8.99E+00 EPA_114 290 to 350 7.78E+00 NIST 230 to 325 -7.12E-01 NSF_SUV 290 to 450 9E-02 SERC 290 to 324 5E-02 USDA_270,386,387 300 to 368 5E-02 ASRC_RSS 290 to 350 3.66E+00 USDA_U1K 290 to 400 -1.14E+00 YES_RSS 290 to 350 -1.14E+00 Instrument Coefficient, [c.sub.1] Coefficient, [c.sub.2] EPA_101 -5.61E-02 8.71E-05 EPA_114 -4.78E-02 7.32E-05 NIST 5.06E-03 -8.85E-06 NSF_SUV 0 0 SERC 0 0 USDA_270,386,387 0 0 ASRC_RSS -2.28E-02 3.55E-05 USDA_U1K 2.91E-03 -4.13E-06 YES_RSS 7.62E-03 -1.26E-05
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Table 1.1 Instruments present during the 1997 North American Interagency Intercomparison of Ultraviolet Monitoring Spectroradiometers Agency Lable Participating spectroradiometers Serial no. EPA EPA_101 Sci-Tec Brewer MKIV 101 EPA EPA_114 Sci-Tec Brewer MKIV 114 NIST NIST RSI NSF NSF_SUV BSI SUV-150 11-002 SERC SERC SERC SR-18 UI USDA USDA_UIK U1000 Spectroradiometer ASRC ASRC_RSS UV-RSS Spectrograph 104 USDA USDA_270 UV-MFRSR 270 USDA USDA_386 UV-MFRSR 386 USDA USDA_387 UV-MFRSR 387 YES YES_RSS UV-RSS Spectrograph Agency Purpose EPA Monitoring EPA Monitoring NIST Calibration NSF Monitoring SERC Monitoring USDA Monitoring/Calibration ASRC Research/Monitoring USDA Monitoring USDA Monitoring USDA Monitoring YES Research/Monitoring Ancillary Measurements Instrument Serial No. Yankee UVB-1 Radiometer 940401 Yankee UVB-1 Radiometer 940402 Yankee UVB-1 Radiometer 940404 Solar Light UV-Biometer 1916 Solar Light UV-Biometer 2004 Solar Light UV-Biometer 2005 Li-Cor Photosynthetically Q22666 Active Radiation Sensor (PAR) Normal Incidence 30399 Pryheliometer (NIP) Spectrosun Precision Solar 73-88 Pyranometer (Downwelling) Spectrosun Precision Solar 73-82 Pyranometer (Upwelling) Eppley Precison Infrared 31609F3 Pyrgeometer (Downwelling) Eppley Precison Infrared 31608F3 Pyrgeometer (Upwelling) Total Sky Imager (TSI) Meteorological Instruments Measurement Instrument Temperature and Relative Humidty Vaisala #R2410094 Barometric pressure Vaisala P173002 Table 3.1 Spectroradiometer specifications Participant/Network EPA_101 NIST EPA_114 Spectroradiameter Model Brewer MKIV RSI Manufacturer Sci-Tec NIST Serial Number 101, 114 Prototype Scanning/Spectrograph/Filter Scanning Scanning Diffraction Grating Grating: Modified Grating: Fastie- /Prism Ebert Ebert Single Double Monochromator Monochromator Detector PMT 9789QA PMT Hamamatsu R1414 Nominal Bandwidth [nm] 0.6 0.8 Range (nm) 286.5 nm to 363.0 nm 290 nm to 325 nm Diffuser Material Teflon (4 cm) Weatherproof Yes No Temperature stabilized Optics No No Detector No No Filter <325 nm 0.50 ndf None +NiSO4+UG11 >324 1.5 ndf +UG11 Dark Current removed Yes Yes Stray Light Removed Yes No Wavelength Registration (nm) 302.3 Primaty Lamp (W) 1000W 1000W Secondary Lamp (W) 50W Participant/Network NSF_SUV SERC Spectroradiameter Model SUV_150 SERC_SR18 Manufacturer Biospherical Smithsonian Instruments SERC Serial Number 11-002 UI Scanning/Spectrograph/Filter Scanning Filter Diffraction Grating Grating: Czerny- /Prism Turner N/A Double Monochromator Detector PMT PMT Hamamatsu R-1657 Nominal Bandwidth [nm] 0.7 2 Range (nm) 280 nm to 600 nm 290 nm to 324 nm in 2 nm steps Diffuser Material Teflon Teflon (0.75 in) Weatherproof Yes Yes Temperature stabilized Optics Yes No Detector Yes Yes Filter None 18 Filters, Barr Interference Dark Current removed Yes Yes Stray Light Removed Yes No Wavelength Registration (nm) 296.7 N/A Primaty Lamp (W) 200W 1000W Secondary Lamp (W) 45W None Participant/Network USDA_270 ASRC_RSS USDA_386 USDA_387 Speetroradiameter Model UV-MFRSR UV-RSS (a) Yankee Manufacturer Environmental SUNY-ASRC Systems Serial Number 280, 386, 387 Prototype, 104 Scanning/Spectrograph/Filter Filter Spectrograph Diffraction Grating Prism: UV-Fused /Prism N/A Silica AR coated 2 Prism Spectrograph Detector Silicon Carbide + CCD GaP 1 X 512 Nominal Bandwidth [nm] 2 0.5 Range (nm) 300 nm to 368 nm 290 nm to 350 nm Diffuser Material 386-Teflon (7 mm) Teflon/ 387-Teflon Spectralon (0.25 in) 270-Spectralon Weatherproof Yes Yes Temperature stabilized Optics Yes Yes Detector Yes Yes Filter 7 Filters. Barr [NiSO.sub.4] X Interference 5[H.sub.2]0 + VG5 Dark Current removed Yes Yes Stray Light Removed No No Wavelength Registration (nm) N/A Primaty Lamp (W) 1000W 1000W Secondary Lamp (W) None Participant/Network USDA_UIK YES_RSS Speetroradiameter Model U1000 UV_RSS (a) Yankee Manufacturer ASRC + Environmental Instruments SA Systems Serial Number Prototype Prototype Scanning/Spectrograph/Filter Scanning Spectrograph Diffraction Grating Grating: 1-meter Prism: UV-Fused /Prism Czemy Turner Silica uncoated Double Double Monochromator Monoebromator Detector PMT Hamamatsu CCD R2371-02 256x1024 Nominal Bandwidth [nm] 0.1 0.6 Range (nm) 290 nm to 410 nm 295 nm to 345 nm Diffuser Material PTFE (1 in) Teflon/ Spectralon (0.25 in) Weatherproof Yes Yes Temperature stabilized Optics Yes Yes Detector Yes Yes Filter Solar Blind Filter Dark Current removed Yes Yes Stray Light Removed No No Wavelength Registration (nm) Primaty Lamp (W) 1000W Secondary Lamp (W) 20W (a)Rotating Shadowband Radiometer. Table 3.2 Channel indicator, nominal and actual center wavelength, bandwidth, and maximum trnasmittance for each filter of the SERC SR-18 instrument, serial number UI Nominal Actual center center wavelength wavelength Bandwidth Maximum Channel (nm) (nm) (nm) transmittance I 290 290.00 2.18 0.1124 H 292 291.96 2.08 0.1384 G 294 293.83 2.32 0.1602 F 296 295.87 2.24 0.1076 E 298 297.95 2.22 0.1219 D 300 299.74 2.08 0.1235 C 302 301.53 2.13 0.1313 B 304 303.81 2.63 0.1675 A 306 305.98 2.23 0.1452 J Dark K 308 307.40 2.33 0.1580 L 310 309.61 2.08 0.1985 M 312 312.36 2.09 0.1543 N 314 314.19 2.29 0.1331 O 316 315.69 2.34 0.1447 P 318 317.99 2.47 0.1546 Q 320 320.65 2.61 0.1618 R 322 322.44 2.28 0.1975 S 324 323.42 2.27 0.1997 T Dark Table 3.3 Channel indicator, nominal and actual center wavelength, and bandwidth for each filter of USDA instruments 270, 386 AND 387 Nominal center Actual center Channel wavelength wavelength Bandwidth (nm) (nm) (nm) Unit 270 0 300 299.73 2.31 1 305 305.42 2.15 2 311 311.47 2.28 3 317 317.65 2.18 4 325 325.48 1.89 5 332 332.46 2.03 6 368 367.78 1.71 Unit 386 0 300 300.36 2.13 1 305 305.84 2.23 2 311 311.90 2.43 3 317 318.25 2.24 4 325 326.01 1.88 5 332 332.93 2.14 6 368 368.44 1.76 Unit 387 0 300 300.37 2.17 1 305 305.69 2.23 2 311 311.81 2.39 3 317 318.20 2.20 4 325 325.94 1.85 5 332 333.04 2.13 6 368 368.41 1.81 Table 5.1 Summary of stray-light, wavelength accuracy and bandwidth Participant/Network EPA_101 EPA_114 NIST Stray-Light (HeCd) 3x[10.sup.-5] 6x[10.sup.-5] < [10.sup.-5] (a) at 300 nm Wavelength Accuracy Mean (Offset) -0.006 -0.025 +0.000 RMS [+ or -] 0.029 [+ or -] 0.027 [+ or -] 0.012 Bandwidth (nm) 0.58 0.58 0.85 at 325 nm USDA_270 Participant/Network NSF_SUV SERC USDA_386 USDA-387 Stray-Light (HeCd) < [10.sup.-6] 4x[10.sup.-5] at 300 nm Wavelength Accuracy Mean (Offset) +0.3 (day 260) -0.06 (day 259) RMS [+ or -] 0.012 (day 259) Bandwidth (nm) 0.70 2 nominal 2 nominal at 325 nm Participant/Network ASRC_RSS USDA_U1K YES_RSS Stray-Light (HeCd) 2x[10.sup.-6] 2x[10.sup.-10] at 300 nm Wavelength Accuracy Mean (Offset) +0.013 +0.016 +0.006 RMS [+ or -] 0.010 [+ or -] 0.007 [+ or -] 0.011 Bandwidth (nm) 0.53 0.11 0.61 at 325 nm (a)At 320 nm. Table 5.2 Dates, lamps, times, and instrument temperatures of spectral scans determining responsivity Instrument Instrument temperature Day Lamp Time (UTC) ([degrees]C) EPA_101 266 96599 21.79 19.67 261 96598 2.96 24.51 EPA_114 263 96599 21.64 15.94 266 96599 21.29 17.8 NIST 260 E002 22.41 15.08 260 96599 23.29 11.78 NSF_SUV 261 96599 0.75 NA 261 96598 1.60 NA 263 96598 18.99 NA 268 96599 20.90 NA 268 96598 22.78 NA SERC 262 96599 0.15 31.82 263 96599 20.22 19.23 267 96599 1.38 20.14 USDA_270 261 96599 1.17 NA 263 96598 13.52 NA 268 96599 16.4 NA USDA_386 261 96598 2.38 NA 263 96598 13.03 NA 268 96599 17.62 NA USDA_387 261 96598 1.82 NA 263 96598 12.85 NA 268 96599 17.11 NA ASRC_RSS 261 96598 NA NA 264 96598 NA NA 268 96599 NA NA USDA_U1K 261 96598 23.61 NA 264 96598 1.02 NA 268 96599 1.02 NA Table 5.3 Relative standard uncertainties from all components during responsivity measurements at selected wavelengths. Relative standard uncertainty (%) Component Wavelength (nm) EPA_101 EPA_114 NIST NSF_SUV Lamp Irradiance 290 1.22 1.22 1.22 1.22 320 0.91 0.91 0.91 0.91 Size 350 0.68 0.68 0.68 0.68 Goniometry 0.09 0.09 0.05 0.03 Current 0.46 0.46 0.36 0.30 (random) 290 0.06 0.06 0.06 0.06 320 0.05 0.05 0.05 0.05 350 0.05 0.05 0.05 0.05 Current 290 0.11 0.11 0.11 0.11 (systematic) 320 0.10 0.10 0.10 0.10 350 0.09 0.09 0.09 0.09 Alignment All 0.39 0.39 0.39 0.39 Instrument Wavelength 290 0.36 0.08 0.04 0.04 320 0.11 0.19 0.02 0.15 350 0.16 0.04 0.06 0.17 Signal 290 0.82 0.50 0.20 0.56 320 0.49 0.36 1.31 0.28 350 0.47 0.48 1.67 0.19 Combined Random 290 0.82 0.50 0.21 0.56 320 0.49 0.36 1.31 0.28 350 0.47 0.48 1.67 0.20 Systematic 290 1.41 1.37 1.34 1.32 320 1.11 1.12 1.12 0.97 350 0.93 0.92 0.87 0.86 Relative standard uncertainty (%) Component SERC USDA_MFRSR ASRC_RSS USDA_U1K (270,386,387) Lamp Irradiance 1.22 1.02 1.10 1.22 0.91 0.91 0.91 0.91 Size 0.78 0.83 0.68 Goniometry 0.02 0.01 0.01 0.05 Current 0.27 0.11 0.11 0.36 (random) 0.06 0.06 0.06 0.06 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Current 0.11 0.11 0.11 0.11 (systematic) 0.10 0.10 0.10 0.10 0.09 0.09 0.09 Alignment 0.39 0.39 0.86 0.86 Instrument Wavelength 0.19 0.18 0.08 0.04 0.15 0.14 0.00 0.04 0.11 0.06 0.04 Signal 0.23 (0.13,0.08,0.09) 5.2 0.54 0.99 (0.28,0.09,0.64) 1.6 0.62 (0.14,0.07,0.64) 14.8 0.63 Combined Random 0.24 (0.14,0.10,0.11) 5.2 0.54 0.99 (0.28,0.10,0.64) 1.6 0.62 (0.15,0.09,0.64) 14.8 0.63 Systematic 1.33 1.05 1.40 1.54 1.04 1.01 1.26 1.31 0.89 1.20 1.15 Table 6.1 Dates and times, indicated by an "X," at which participating instruments were performing synchronized scans of solar ultraviolet irradiance Day Time EPA_101 EPA_114 NSF_SUV SERC ASRC_RSS USDA_U1K 260 00:00 X 00:30 X 01:00 X 12:00 X 12:30 X 13:00 X X 13:30 X 14:00 X X 14:30 X X 15:00 X X X 15:30 X X X 16:00 X X 16:30 X X X 17:00 X X 17:30 X X 18:00 X X X 18:30 X X X 19:00 X X X 19:30 X X X 20:00 X X X 20:30 X X 21:00 21:30 22:00 22:30 23:00 23:30 261 00:00 X 00:30 X 01:00 X 12:00 X X 12:30 X X 13:00 X X 13:30 X X 14:00 X X 14:30 X 15:00 X 15:30 X X 16:00 X X 16:30 X 17:00 X 17:30 X X 18:00 X X X 18:30 X X X 19:00 X X X 19:30 X X 20:00 X X 20:30 X X 21:00 X 21:30 X 22:00 X 22:30 X 23:00 X 23:30 262 00:00 00:30 01:00 12:00 X 12:30 X 13:00 X 13:30 X 14:00 X 14:30 X X 15:00 X 15:30 X X 16:00 X X 16:30 X 17:00 X X 17:30 X X 18:00 X X 18:30 X X 19:00 X X 19:30 X X 20:00 X X 20:30 X X 21:00 X X 21:30 X X 22:00 X X 22:30 X X 23:00 X X 23:30 X X 263 00:00 X X 00:30 X X 01:00 X X 12:00 X X 12:30 X X 13:00 X X 13:30 X X 14:00 X X 14:30 X X 15:00 X X 15:30 X X 16:00 X X 16:30 X X 17:00 X X 17:30 X X X 18:00 X X 18:30 X X 19:00 X X 19:30 X X 20:00 X 20:30 X X X 21:00 X X X 21:30 X X X 22:00 X X X 22:30 X X X 23:00 X X 23:30 X X 264 00:00 X X 00:30 X X 01:00 X X 12:00 X 12:30 X 13:00 X 13:30 X 14:00 X 14:30 X 15:00 X 15:30 X 16:00 X 16:30 X 17:00 X 17:30 X 18:00 X 18:30 X 19:00 X X 19:30 X X 20:00 X X 20:30 X X 21:00 X X 21:30 X X 22:00 X 22:30 X X 23:00 X 23:30 X 265 00:00 X X 00:30 X X 01:00 X 12:00 X 12:30 X X 13:00 X X 13:30 X X 14:00 X X 14:30 X X 15:00 X X 15:30 X X 16:00 X 16:30 X 17:00 X 17:30 X X 18:00 X X X 18:30 X X 19:00 X X X 19:30 X X X 20:00 X X X 20:30 X X X 21:00 X X X 21:30 X X X 22:00 X X X 22:30 X X X 23:00 X X X 23:30 X X X 266 00:00 X X 00:30 X X 01:00 X X 12:00 X X 12:30 X X 13:00 X X 13:30 X X 14:00 X X 14:30 X X 15:00 X X X 15:30 X X X 16:00 X X X 16:30 X X X 17:00 X X X 17:30 X X X 18:00 X X X 18:30 X X X 19:00 X X 19:30 X X 20:00 X X 20:30 X X 21:00 X X 21:30 X X 22:00 X 22:30 X 23:00 X 23:30 X 267 00:00 X X 00:30 X X 01:00 X 12:00 X 12:30 X X 13:00 X X 13:30 X X 14:00 X X 14:30 X X 15:00 X X X X X 15:30 X X X X 16:00 X X X X X X 16:30 X X X X X X 17:00 X X X X X X 17:30 X X X X X X 18:00 X X X X X X 18:30 X X X X X 19:00 X X X X X 19:30 X X X X X 20:00 X X X X X X 20:30 X X X X X X 21:00 X X X X X X 21:30 X X X X X X 22:00 X X X X X X 22:30 X X X X X X 23:00 X X X X X X 23:30 X X X X X 268 00:00 X X X X 00:30 X X X 01:00 X X X 12:00 X 12:30 X X 13:00 X X 13:30 X X 14:00 X X Day Time USDA_270 USDA_386 USDA_387 260 00:00 X 00:30 X 01:00 X X X 12:00 X X X 12:30 X X X 13:00 X X X 13:30 X X X 14:00 X X X 14:30 X X X 15:00 X X 15:30 X X X 16:00 X X X 16:30 X X X 17:00 X X X 17:30 X X X 18:00 X X X 18:30 X X X 19:00 X X X 19:30 X X X 20:00 X X X 20:30 X X X 21:00 X X 21:30 X X 22:00 X X 22:30 X X 23:00 X X 23:30 X X 261 00:00 00:30 01:00 12:00 X 12:30 X 13:00 X 13:30 X 14:00 X 14:30 X 15:00 X 15:30 X 16:00 X 16:30 X 17:00 X 17:30 X 18:00 X 18:30 X 19:00 X 19:30 X 20:00 X 20:30 X 21:00 X 21:30 X 22:00 X 22:30 X 23:00 X 23:30 X 262 00:00 X X 00:30 X X X 01:00 X X X 12:00 X X X 12:30 X X X 13:00 X X X 13:30 X X X 14:00 X X X 14:30 X X X 15:00 X X X 15:30 X X X 16:00 X X X 16:30 X X X 17:00 X X X 17:30 X X X 18:00 X X X 18:30 X X X 19:00 X X X 19:30 X X X 20:00 X X X 20:30 X X X 21:00 X X X 21:30 X X X 22:00 X X X 22:30 X X X 23:00 X X X 23:30 X X X 263 00:00 00:30 X X X 01:00 X X X 12:00 X X X 12:30 X X X 13:00 X X X 13:30 X X X 14:00 X X X 14:30 X X X 15:00 X X X 15:30 X X X 16:00 X X X 16:30 X X X 17:00 X X X 17:30 X X X 18:00 X X X 18:30 X X X 19:00 X X X 19:30 X 20:00 X 20:30 X 21:00 X 21:30 X X 22:00 X 22:30 X 23:00 X X X 23:30 X X X 264 00:00 X X X 00:30 X X X 01:00 X X X 12:00 X X X 12:30 X X X 13:00 X X X 13:30 X X X 14:00 X X X 14:30 X X X 15:00 X X X 15:30 X X X 16:00 X X X 16:30 X X X 17:00 X X X 17:30 X X X 18:00 X X X 18:30 X X X 19:00 X X X 19:30 X X X 20:00 X X X 20:30 X X X 21:00 X X X 21:30 X X X 22:00 X X X 22:30 X X X 23:00 X X X 23:30 X X X 265 00:00 X X X 00:30 X X X 01:00 X X X 12:00 X X X 12:30 X X X 13:00 X X X 13:30 X X X 14:00 X X X 14:30 X X X 15:00 X X X 15:30 X X X 16:00 X X X 16:30 X X X 17:00 X X X 17:30 X X X 18:00 X X X 18:30 X X X 19:00 X X X 19:30 X X X 20:00 X X X 20:30 X X X 21:00 X X X 21:30 X X X 22:00 X X X 22:30 X X X 23:00 X X X 23:30 X X X 266 00:00 X X X 00:30 X X X 01:00 X X X 12:00 X X X 12:30 X X X 13:00 X X X 13:30 X X X 14:00 X X X 14:30 X X X 15:00 X X X 15:30 X X X 16:00 X X X 16:30 X X X 17:00 X X X 17:30 X X X 18:00 X X X 18:30 X X X 19:00 X X X 19:30 X X X 20:00 X X X 20:30 X X X 21:00 X X X 21:30 X X X 22:00 X X X 22:30 X X X 23:00 X X X 23:30 X X X 267 00:00 X X X 00:30 X X X 01:00 X X X 12:00 X X X 12:30 X X X 13:00 X X X 13:30 X X X 14:00 X X X 14:30 X X X 15:00 X X X 15:30 X X X 16:00 X X X 16:30 X X X 17:00 X X X 17:30 X X X 18:00 X X X 18:30 X X X 19:00 X X X 19:30 X X X 20:00 X X X 20:30 X X X 21:00 X x A 21:30 X X X 22:00 X X X 22:30 X X X 23:00 X X X 23:30 X X X 268 00:00 X X X 00:30 X X X 01:00 X X X 12:00 X X X 12:30 X X X 13:00 X X X 13:30 X X X 14:00 X X X Table 6.2 Days adn times of responsivity scans used to calculate solar irradiance on Julian Day 267 Instrument Day/TIME (UTC) Lamp Number EPA_101 266/21.8 96599 EPA_114 266/21.3 96599 NSF_SUV 268/20.9 96599 268/6.2 45W Internal SERC 267/1.4 96599 USDA_270 268/16.4 96599 USDA_386 268/17.6 96599 USDA_387 268/17.1 96599 ASRC_RSS 263/- 96598 USDA_U1K 266/1.0 96599
Operation of the National Science Foundation's Polar Ultraviolet Monitoring Network, along with participation in this Intercomparison, was funded through contract OPP-8922832 from Antarctic Support Associates under the direction of Dr. Polly Polly Biotechnology A Poll Dorset sheep cloned from sheep skin cells, which has a human gene in each cell. See Dolly. Penhale at the National Science Foundation, Office of Polar Programs. Operation of the National Ultraviolet Monitoring Network, along with participation in this Intercomparison, was funded through the U.S. Environmental Protection Agency Assistance. Development of the U1000 Ultraviolet Scanning Radiometer, participation in this Intercomparison, and operation of the USDA UV Network was funded by the UV-B Radiation Monitoring Program of the U.S. Department of Agriculture's Cooperative State Research, Education, and Extension Service through contracts 96-34263-3527, 96-34263-6888, 96-34263-8506 under the direction of Dr. Henry Tyrell.
Accepted: August 28, 2001
(1.) Certain commercial equipment, instruments, or materials are identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.
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Microscopic organisms, such as bacteria, viruses, algae and fungi.
Mentioned in: Animal Bite Infections , and Materials, Lewis Publishers, Boca Raton Boca Raton (bō`kə rətōn`), city (1990 pop. 61,492), Palm Beach co., SE Fla., on the Atlantic; inc. 1925. Boca Raton is a popular resort and retirement community that experienced significant industrial development in the 1970s and 80s. , FL (1993).
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The name James Kerr can refer to:
Rive (plural : rives) is a French word meaning "bank" (of a river). Geography
Rives is the name of several places: France
Rives is the name of 2 communes in France:
(5.) Edward Early, Ambler Thompson, Carol Johnson Carol Alfred Johnson (1903 - 30 July 2000) was a British Labour politician. He was Member of Parliament for Lewisham South from 1959 until the general election of February 1974, when the constituency was abolished by boundary changes. References , John DeLuisi, Patrick Disterhoft, David Wardle, Edmund Wu, Wanfeng Mou, Yongchen Sun, Timothy Lucas, Tanya Mestechkina, Lee Harrison, Jerry Berndt, and Douglas Hayes, The 1995 North American Interagency Intercomparison of Ultraviolet Monitoring Spectroradiometers, J. Res. Natl. Inst. Stand. Technol. 103. 15-62 (1998).
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SGP Schering-Plough (stock symbol)
SGP Stability and Growth Pact
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(18.) CRC (Cyclical Redundancy Checking) An error checking technique used to ensure the accuracy of transmitting digital data. The transmitted messages are divided into predetermined lengths which, used as dividends, are divided by a fixed divisor. Handbook of Chemistry and Physics, CRC Press, Inc., Boca Raton (1979) pp. E-227-E-228.
(19.) E. A. Early and A. Thompson, Irradiance of Horizontal Quartz-Halogen Standard Lamps, J. Res. Natl. Inst. Stand. Technol. 101, 141 (1996).
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Branch of analysis devoted to identifying elements and compounds and elucidating atomic and molecular structure by measuring the radiant energy absorbed or emitted by a substance at characteristic wavelengths of the electromagnetic spectrum (including gamma ray, , Academic Press, San Diego (1984) pp. 8-10.
(21.) H. Slaper, H. A. J. M. Reinen, M. Blumehaler, M. Huber, and F. Kuik, Comparing ground-level spectrally spec·tral
1. Of or resembling a specter; ghostly.
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Dedicated to the Fond Memory of Douglass Hayes and David Bigelow.
About the authors: Kathleen Lantz and Patrick Disterhoft are members of the Cooperative Institute for Research in Environmental Science of the University of Colorado University of Colorado may refer to:
John DeLuisi is the director of the Surface Radiation Research Branch of the NOAA Air Resources Laboratory. The National Oceanic and Atmospheric Administration is an agency of the U.S. Department of Commerce.
Edward Early and Ambler Thompson are members of the Optical Technology Division of the NIST Physics Laboratory.
Wanfeng Mou and Thomas Taylor are members of the National Ultraviolet Monitoring Center at the University of Georgia.
James Ehramjian, Germar Bernhard, Lauriana Cabasua, and James Robertson are with Biospherical Instruments Inc., which operates the National Science Foundation's Polar Ultraviolet Monitoring Network.
Doug Hayes was a member of the Smithsonian Environmental Research Center Solar Radiation solar radiation,
n the emission and diffusion of actinic rays from the sun. Overexposure may result in sunburn, keratosis, skin cancer, or lesions associated with photosensitivity. Laboratory of the Smithsonian Institution Smithsonian Institution, research and education center, at Washington, D.C.; founded 1846 under terms of the will of James Smithson of London, who in 1829 bequeathed his fortune to the United States to create an establishment for the "increase and diffusion of .
Lee Harrison, Jerry Berndt, and Peter Kiedron are with the Atmospheric Science Research Center at SUNY, Albany.
James Slusser, Dave Bigelow, Bill Durham, and George Janson are with Natural Resource Ecology Laboratory, at Colorado State University which operates the USDA UV Monitoring Program.
Arthur Beaubien and Mark Beaubien are with Yankee Environmental Systems, Inc., in Turner Falls, MA.
The National Institute of Standards and Technology is an agency of the Technology Administration, U.S. Department of Commerce.