Aerosols-Climate Interactions: The Relationship between Desert Dust and Atmospheric Convection

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This research project will examine how mineral dust from the surface of arid land is injected into the atmosphere by strong convective plumes, especially those whirling ones called "dust devils." The investigators suspect that dust devils are a significant source of atmospheric dust and therefore affect climate on regional and global scales. The objectives of this proposal are to measure the surface flux of dust and its vertical transport and to use those measurements to develop parameterized representations of this source of dust from arid regions. Two hypotheses form the basis for this work: (i) coherent convective plumes and dust devils play a significant role in the vertical transport of dust; and (ii) the magnitude of that transport is increased when the surface is disturbed by plowing and other agricultural practices, which also cause an increase in the intensity of the convective motions. Measurements will be made at a field site in Arizona using a lidar, a small instrumented aircraft, and surface instruments. The research will also include testing of a new instrument that can measure the surface flux of aerosols. A web-based educational component will describe dust devils and related phenomena and will contrast how they occur on Earth and on Mars. The expected outcome of the research will be to test and refine a proposed new representation of the amount and distribution of dust that enters the atmosphere through dust devils and other coherent convective plumes. This parameterized representation will then be available for inclusion in climate models and other transport models, which in turn can provide improved estimates of the global distribution of dust and its effect on the climate system.