RECENT ATMOSPHERIC STUDIES AT SPL

A three-year study by DRI scientists, Dr. Randy Borys and colleague Dr. Doug Lowenthal , in collaboration with the National Center for Atmospheric Research, indicates that polluted air can reduce winter snowpack (equivalent water content) contributed during individual storms by 50 percent. Their research is zeroing in on the long-term reduction in annual snowpack, which could be as much as 25 percent. National Geographic Today featured SPL research in a televised interview with Randy Borys and others, who discuss the unique setting and rare scientific capabilities available at this high-elevation atmospheric research facility.

Water authorities seem to be taking notice, and with some alarm. "In normal years, you might not notice a decrease in the water content of snow, but after five years of drought, every drop counts," Borys said. Even though pollution does not create droughts-which are caused by larger atmospheric and climatic conditions-dirty air could be making the situation worse.

"Tiny" (0.1-1 micrometers in diameter) naturally occurring and pollutant-formed aerosol particles, known as cloud condensation nuclei, form microscopic cloud droplets, and these droplets typically form ice crystals or combine with other crystals to form snowflakes. The work of Borys, Lowenthal, and others has shown that when aerosol particles from air pollution increase the number of cloud condensation nuclei, the number of droplets also increases, but the average diameter of cloud droplets is reduced. This process serves to tie up more of the available moisture in the cloud, and the smaller, more numerous droplets essentially disperse and evaporate before accumulating into droplets large enough to fall to the ground.

Sulfate, nitrate, and possibly some organic compounds in the form of tiny atmospheric particles are the culprits. These particles are the byproducts of almost any combustion process, including natural fires. However, it is the persistent generation of pollution containing these minute aerosol particles, day in and day out, that sets the stage for the process to occur. Channel 8 KOLO-TV in Reno, Nevada, recently covered the work of DRI scientists who are researching this link between air pollution and drought conditions.

This work was recently the subject of an article in the Los Angeles Times. Related publications may be found on the SPL web site under "references".