Atmospheric dust may play a key role in precipitation, according to researchers who flew aircraft and used ground monitoring stations in California to study dust particles carried over the Pacific Ocean from Asia. They presented their results last week at the American Chemical Society national meeting in Denver.
Dust in the atmosphere is known to play a role in ice formation in clouds, but its effect on precipitation is poorly understood. Dust from Asia accounts for about one-third of global dust emissions. The topography and meteorology of the region causes dust to rise high in the atmosphere, where it can be transported across the Pacific.
University of California, San Diego, chemistry professor Kimberly A. Prather and colleagues established correlations between the Asian dust and the quantity of ice in clouds over California and snowfall amounts in the Sierra Nevada Mountains. They did so by examining the properties of atmospheric aerosol particles as well as the composition of precipitation samples using mass spectrometry. They tracked dust transport using satellite and meteorological data, and even traced one Asian dust storm in 2009 that eventually added 16 inches to the Sierra snowpack (J. Geophys. Res., DOI: 10.1029/2010jd015351).
The work is part of a multiyear study of cloud properties and precipitation in California known as CalWater.
Because clouds and snowpack also affect climate, the new analysis may influence regional and worldwide climate modeling, commented atmospheric chemist Susan Solomon, adjunct professor at the University of Colorado department of atmospheric and oceanic sciences. She was not involved in the work.
Solomon said human activity stirs up dust in a lot of places, so the results may be applicable beyond the dust from Asia that affects California.