Competing hypotheses for the diameter dependence of terrestrial and martian dust devil frequency are assessed using new field observations from two sites in the southwestern United States. We show that at diameters less than 12m, our observed dust devil size–frequency distributions are better fit by an exponential function than by a power law formulation, and discuss the implications for larger dust devils on Earth and Mars.

Introduction: Dust devils are common on both the Earth and Mars [1]. These small whirlwinds—caused by heating of the surface and made visible by entrained dust and sand —act to enhance aerosols in the atmosphere through vertical transport of mineral dust (Figure 1). Dust devils are suspected to be the mechanism that supports the ongoing dustiness of the martian atmosphere, and their dust-lifting capabilities have begun to be included in General Circulation Models (GCMs). This past summer, a field campaign was initiated to study terrestrial dust devils and ambient meteorology in both Eloy, Arizona and Eldorado Valley, Nevada. The main purpose of the work described in this abstract is to relate measured ambient vertical vorticity with simultaneous observations of dust devil size and frequency [2, 3].

STEREO-CAMERA SURVEY AND GIS TO CALCULATE THE SIZE-FREQUENCY DISTRIBUTION OF DUST DEVILS IN THE SOUTHWEST USA. M. R. Balme, S.M. Metzger, A. Pathare, N. Renno F. Saca, A. Spiga, M.C. Towner. Planetary Science Institute, Tucson, AZ, USA (mbalme@psi.edu). Dept. of Earth and Environmental Sciences, The Open University, Milton Keynes, UK, Dept. of Atmospheric, Oceanic & Space Sciences, University of Michigan, Ann Arbor, MI, USA. Dept. of Physics and Astronomy, The Open University, Milton Keynes, UK. 5 Dept of Earth Science and Engineering, Imperial College London, UK.