Characterization of the Effects of a Severe Drought on Dust Lifting

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Dust particles in the atmosphere are known to affect weather and climate through the absorption and scattering of radiation and through their ability to affect cloud processes. In order to better understand the variability of dust loading in the atmosphere it is important to study how dust aerosols are transported from the surface to the atmosphere, a process known as saltation. This award will provide funding for observations and analysis of data from the Owens Lake playa in California, a dry lake bed that is known as a significant source of dust pollution. The research will seek to determine the roles of soil particle size distribution, crusted soil, water content, and dust electrification in saltation. The long-term societal benefits of the project are through better representation of dust in the weather and climate system, thereby improving forecasts. In the shorter-term the researchers will work with the Owens Valley air quality officer, offering a direct link to health effects, and the project will also contribute to the education and training of students. This research project will investigate the effects of soil composition, particle size distribution, and soil water content on the depth of the saltation layer, the intensity of saltation, the electric fields generated by saltation, and the PM2.5 aerosol concentration as a function of wind shear stress in a variety of weather phenomena and climate conditions. The campaign is primarily observational, with instrumentation residing in the Owens Lake salty playa in California. The three main objectives of the work are in the following areas: 1) Saltation and dust lifting - Continued and improved measurements will be used to test competing hypotheses about the correlation between vertical dust flux and near surface humidity, 2) Effects of electric fields on dust lifting - Electric field data would be used to test the hypothesis that electric forces attract saltating particles toward the surface, inhibiting increases in the depth of the saltation layer with increases in wind shear stress at the surface, and 3) Dusty weather phenomena - The researcher will study the intensity and depth of the saltation layer and dust lifting in weather phenomena ranging from small-scale dusty plumes and vortices to larger-scale dust storms to accurately quantify the contributions from each to the dust cycle. The hypothesis that dust lifted by convective events is much richer in fine particles will also be tested.