A Mars Dust Model with Interactive Dynamics, Radiation, and Microphysics

Abstract:

Variability of the present day Martian climate is dominated by globally enveloping dust storms that recur with a frequency of approximately three years. Small-scale aeolian processes predictably generate local seasonal storms. However, factors that enhance local storm strength and grow local phenomenon to global scales are poorly understood. Research with Martian general circulation models (GCM) has recently demonstrated a strong correlation between dust storm generation, strength and long-term stability and the global distribution of dust reservoirs and their temporal permanence. Here we present results from the NCAR Mars Community Atmosphere Model (CAM) coupled with a fully interactive dust microphysics scheme. Dust devil lifting and saltation wind driven lifting are parameterized in the emission scheme. Mass is distributed into 20 size bins with a radius range of 0.1 to 8 microns. The initial radial size distribution is log-normal with a sigma value of 1.5. Dust is allowed to advect horizontally and is removed from the atmosphere by dry deposition. Dust also impacts the radiative heating rate, as do water clouds.The large number of dust bins allows for the opportunity to track the size distribution of dust deposits and investigate the long term stability of dust source regions as a function of particle size.