Aerosols-Climate Interactions: Characterization of Saltation, Dust Lifting, and Dust Electrification in Important Dust Source Regions

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

Investigators

Abstract

Aerosols produce a direct climate forcing by scattering and absorbing solar and infrared radiation, and an indirect forcing by altering cloud processes. Since human activity causes significant increases in the concentration of atmospheric aerosols, it is important to understand the effects of aerosols on climate. Despite considerable progress in our understanding of aerosols-climate interactions, climate forcing by mineral dust aerosols is still one of the most uncertain processes in current climate models (IPCC, 2007). Therefore, it is important to study the lifting and transport of dust aerosols so that aerosol climate forcing can be assessed accurately. Intellectual merits: Mineral dust aerosols are lifted (ejected into the atmosphere) by saltation and transported away from the surface by convective plumes (in particular, their updrafts), convective vortices (dust devils), dust storms (dust lifting by gust fronts), and large-scale winds (wind-blown dust). So far most research has focused on studies of dust lifting by large-scale processes such as dust storms and wind-blown dust because they are the most important contributors to the global aerosol budget. However, recent studies suggest that small-scale processes such as convective plumes and vortices also play an important role on the global mineral dust budget. This suggestion is consistent with evidence that variations in the annual dust cycle of West African dust "hot spots" are strongly correlated with variations in small-scale wind gusts produced by dry boundary layer convection, but not with variations in the mean surface wind. In order to fully understand aerosols-climate interactions we must understand the basic physical processes involved in saltation and their variability with soil and weather conditions. This project will achieve this goal by studying saltation and dust lifting in Nevada, an area where small-scale dust lifting processes are ubiquitous, the Owens Dry Lake, one of the most important dust source areas in the U.S. Broader impacts: The research has the potential to have a broad impact on science and society. Besides studying an important scientific problem key to our understanding of global climate change, we will make our data and models available to the scientific community. We have an educational website that provides simple physical explanations for the formation of convective plumes, dust devils, and dust storms. The website will include descriptions of the weather and climate of Nevada, the Owens Dry Lake. Finally, this project will contribute to the training of graduate students.