Drought Intensifies Dust Activities in the United States

Drought is one of the most costly natural hazards in the United State. Multi-model simulations have projected significantly drier condition in the southwest and Central Great Plains in the later half of the 21^st century compared to the 20^th century. These projected drier areas are collocated with the two major sources of mineral dust aerosols along the two sides of the Rockies: the deserts and ephemeral lakes in the western U.S. and anthropogenic sources associated with farming in the Great Plains.  Whether and how will droughts intensify the dust activities are investigated using dust optical depth (DOD) derived from MODIS Deep Blue aerosol products and fine soil concentration from IMPROVE stations for the present-day climate and CMIP output for future projections.  The recent severe drought events in the Great Plains in 2011 and 2012 and in California in 2011-2014 strongly increased dust activities in these regions. In the three regions examined here (Southern and Northern Great Plains, and Southwestern U.S.), spring and summer DOD is not only significantly influenced by precipitation but also by the vegetation density manifested as leaf area index, particularly in the northern Great Plains in spring and southwestern U.S. in summer.

            The near surface fine dust concentration also shows significant increasing trend from 1990-2014 over the Southwest (mainly Arizona and New Mexico) in spring and over the Great Plains in summer, consistent with the drying trend in the areas.