DUST DEVIL STUDIES ON MARS ANALOG ARID SURFACES

The Eldorado Valley Dust Devil Project is a collaborative effort to understand the meteorologic, aerodynamic and geologic conditions that spawn natural thermal vortices, determine the detailed anatomy and erosive power of dust devils, and calculate their sediment flux. In recent years we have also sought to detect their electric field properties and potential discharges. This effort is conducted in support of Mars program goals yet also contributes to the evaluation of terrestrial air quality in arid regions. Furthermore, the extensive data set of soil engineering properties is relevant to desert surface process studies. Field areas include the Eldorado Valley playa basin outside Las Vegas, NV, agricultural fields at Eloy, AZ, and Rosamond dry lakebed in the Mohave Desert, CA.

Our primary research tool is an instrumented chase truck carrying over 35 sensors and imaging systems on a 5 m vertical profiling mast, all recorded on a single data logger. The flexible configuration permits comparison of different sensor strategies. In example, 3D wind speeds have been measured with cup, propeller, and sonic anemometers. One lesson is that a dense array of inexpensive cup anemometers can provide excellent cross-section profiles while sonic anemometers are uniquely capable of measuring rapid, complex pulsations in wind strength. The mobile rig captured a large dust devil four times in > 4 km as it traveled 4.7 m/s across the surface and lasted over 20 minutes. That vortex fluctuated from 35 to 56 m in diameter, developing maximum tangential rotation of 11 to 15 m/s, and vertical lift of 3 m/s. Other recently sampled vortices displayed maximum rotation speeds of 8 to 24 m/s. Pressure, temperature, and dust & sand concentration profiles were also recorded. Cross section visualizations and preliminary flux calculations will be presented