State basks in sun study.

Byline: Greg Bolt The Register-Guard

Call us the Sunshine State.

In a new report that puts Oregon's soggy reputation at risk, researchers at the University of Oregon say sunny skies have become more common - at least in summer. Research presented Tuesday at a national conference shows that sunnier summers in Eugene have boosted the area's annual "sunfall" by 15 percent over the past 25 years.

That's at the high end of data from three stations around the state showing a 10 percent to 15 percent increase in solar radiation in the state since 1979. The data was collected by the UO's Solar Radiation Monitoring Laboratory. Frank Vignola, the lab's director, presented the research results at the 2005 Solar World Congress in another sunny spot, Orlando, Fla.

"Oregon is a state famous for rain, but in fact, Oregon is getting much more sunshine," said Vignola, co-author of the study with Laura Riihimaki, a physics doctoral student at the UO.

Of no surprise to anyone living west of the Cascades, the study also found that winters in Oregon are becoming cloudier. But because winters already were pretty cloudy, the increase in summer sun more than makes up for it, and leaves the state with a net annual increase in the amount of sunshine.

The data run counter to some recent studies suggesting a "global dimming" trend brought on by climate change. Under that theory, the documented increase in average global temperatures over the past decades has fed the mechanism that creates clouds and has reduced sunshine by about 2 percent per decade over much of the globe.

But Vignola said those studies have used instruments that aren't as reliable as those in his lab, and that haven't been gathering data for as long. Vignola's lab has been measuring direct sunlight since 1979 at stations in Eugene, Hermiston and Burns and for shorter times at other stations around the Northwest.

"We are working with the largest and highest quality continuous record in the world," he said.

The instruments have recorded a 10 percent increase in sunny days in Hermiston and Burns, which already basked in more sun than the damp Willamette Valley, and a 15 percent increase in Eugene. Vignola said fewer clouds is the best explanation for the rise in solar radiation but that a comparison of satellite images is needed to confirm that.

Vince McClellan, president of Energy Designs Co., said fewer clouds makes sense to him. McClellan's Eugene company designs and installs solar systems and uses a standard table of solar radiation measurements to calculate how much energy a system will produce in a given location.

The thing is, the solar panels keep producing more energy than what the tables say they should.

"Definitely some of our systems are producing more power than we've estimated," said McClellan, who also teaches photovoltaics at Lane Community College. "And I think that's directly proportional to meteorological input, how much solar insolation would be coming in."

The study was not presented to support evidence for global warming. The vast majority of scientists agree that average temperatures worldwide have risen over the past 100 years - by 1 to 3 degrees in the Northwest, according to a consensus report signed by 49 Northwest scientists and climate experts. But debate goes on over how much of it is because of human activity and how much is natural climate variation and what the consequences of warming will be.

Although more work is needed to fully understand what's going on with the region's atmosphere, the data collected by the solar lab will be helpful in continuing studies of the regional effects of global warming. Riihimaki, the lead author of the study, said it also will be valuable in evaluating power generation issues.

"Now that we've characterized the trend, we can use this data with regional climate models to tell us how global warming is affecting the region and improve our success at predicting climate change in the Northwest," she said.

"Understanding long-term changes and trends in solar radiation is important to agriculture and for assessing the risks and reliability of power generated from hydroelectric and solar energy facilities."