Letter from the editor: now you see it, now you don't.
The poet Carl Sandburg wrote that fog enters quietly on "little cat feet" only to "move on" without a trace.
Fog's stealthy reputation can only be enhanced by Noam David and colleagues' evaluation of an observing concept using the attenuation of microwave signals from cell phone towers (p. 1687). The signals traveling between common commercial towers are sensitive to heavy fog (and they've been used for precipitation detection as well). With increasing load, however, cell providers are updating to higher frequency systems with more sensitivity to the atmosphere. David et al. suggest that the new microwave links could be an effective visibility detection tool. In short, change the observing tool, and suddenly the fog and its intensity gradations are detectable.
While we are accustomed to the furtiveness of fog, Gail Skofronik-Jackson and colleagues reveal the similar smoke and mirrors game played by cold season precipitation (p. 1719). Their winter remote sensing experiment collected snowfall observations of all sorts, and the results remind us that every way of looking for snow has its flaws. Sometimes, snow slyly mixes with other precipitation. Sometimes light snow vanishes from specific radiometer viewing channels. Sometimes the crystals melt too fast for photographic or video recording. Sometimes surface backgrounds obscure snow from downward-looking remote sensors. And so on.
Yet groundwater, precipitation, and even fog follow patterns that help make them a little less elusive. For example, fog patiently lies in wait along cool coastal waters and during nights in the valley. Naturally, Clemens Simmer et al. (p. 1765) are also searching for such patterns as they unlock the secrets of modeling the poorly observed inhomogeneities of the terrestrial system. So many inhomogeneities in the atmosphere are evanescent, but water in the ground traces out much more persistent complications.
To find modeling solutions, Simmer et al. look for the repeating structures, from the tiniest soil pores to whole aquifers, but even nature's boldest stripes slink in and out of view. What looks like structure--like root branching or convective cells--at close examination simply disappears into generic tendencies when you pull back to regard the larger scale. So goes the dilemma of what to sharpen, and what to blur, with the parameters in one's modeling systems.
Sometimes the key to recognizing what prowls in the mists is to look at boundaries where different scales and media interact and might exchange essential patterns. It is the surface, after all, that lures fog to nap in the same places over and over again. Simmer et al. note that--while precipitation is well distributed in the Rur catchment--the surface urbanization gradients etch themselves into various water cycle processes. Meanwhile, the subsurface water distribution is affected by deposits of paleo-rivers--an exchange of vastly different timescales.
Likewise, Businger et al. must mind a geological interface when forecasting a particularly unhealthy form of fog--the sulfur dioxide and sulfate aerosol laden volcanic smog in Hawaii (p. 1667). Apparently even the most ancient earthly processes will creep into our atmospheric lair, if you know where and when to find them.
--Jeff Rosenfeld, Editor-in-Chief
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|Publication:||Bulletin of the American Meteorological Society|
|Date:||Oct 1, 2015|
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