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University Of Oregon Study Says Sunnier Oregon Summers Reflect Global Warming

August 18, 2005
University of Oregon
University of Oregon physicists report clear evidence of climate change according to their analysis of high quality solar radiation data gathered continuously over a 25-year period.

ORLANDO, FLA. (Aug. 9, 2005) -- Summers aregetting sunnier in Oregon, according to evidence presented today byUniversity of Oregon physicists during the 2005 Solar World Congress inOrlando. The study is a first step toward testing and refining regionalclimate models for the Pacific Northwest that will help track globalwarming.

In sharp contrast to reports of increased global dimming, thestudy's researchers reported a 10 to 15 percent increase in solarradiation at sites in Burns, Hermiston and Eugene over the last 25years, according to an initial analysis of data collected since 1979 bythe university's Solar Radiation Monitoring Laboratory.

"Oregon is a state famous for rain but in fact, Oregon isgetting much more sunshine," said Frank Vignola, the laboratory'sdirector and the study's co-author. "In fact, about two-thirds of theNorthwest gets as much or more solar radiation than Florida. Thenorthwestern corner of Oregon, which includes the population center inPortland, gets about 20 percent less."

Vignola and lead author Laura Riihimaki, a physics doctoralstudent, also found that Oregon winters are becoming cloudier. However,solar radiation levels during December average 75 percent less thanJuly, so sunnier summers more than offset the increase in winter cloudcover.

"Now that we've characterized the trend, we can use this datawith regional climate models to tell us how global warming is affectingthe region and improve our success at predicting climate change in theNorthwest," Riihimaki said. "Understanding long-term changes and trendsin solar radiation is important to agriculture and for assessing therisks and reliability of power generated from hydroelectric and solarenergy facilities."

The university's Solar Radiation Monitoring Lab,which collects data throughout the Northwest, is helping develop theinfrastructure to integrate solar resources into the regional energymix.

Though monitoring is done globally, no other site has measuredsolar radiation continuously for such a long period. "We are workingwith the largest and highest quality continuous record in the world,"Vignola said.

Unlike other recent "global dimming" studies, which havereported decreases of about two percent per 10-year-period over largesections of the world, this study analyses direct normal data.

"We have better data because we're looking at this with directbeam instruments which are more stable than global instruments,"Vignola said, explaining that most recent studies on global dimminghave been done with instruments whose sensitivity decreases over time.

The study was funded by Riihimaki's fellowship in the NationalScience Foundation's GK-12 Program at the University of Oregon'sMaterials Science Institute.


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University of Oregon. "University Of Oregon Study Says Sunnier Oregon Summers Reflect Global Warming." ScienceDaily. ScienceDaily, 18 August 2005. <>.
University of Oregon. (2005, August 18). University Of Oregon Study Says Sunnier Oregon Summers Reflect Global Warming. ScienceDaily. Retrieved July 15, 2024 from
University of Oregon. "University Of Oregon Study Says Sunnier Oregon Summers Reflect Global Warming." ScienceDaily. (accessed July 15, 2024).

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