The Vertical Dust Profile Over Gale Crater, Mars

Scott D. Guzewich, C. E. Newman, M. D. Smith, J. E. Moores, C. L. Smith, C. Moore, M. I. Richardson, D. Kass, A. Kleinböhl, M. Mischna, F. J. Martín-Torres, M. -P. Zorzano-Mier, M. Battalio. 2017. The Vertical Dust Profile Over Gale Crater, Mars. Journal of Geophysical Research Planets 122, 12, 2779-2792, DOI: 10.1002/2017JE005420

We create a vertically coarse, but complete, profile of dust mixing ratio from the surface to the upper atmosphere over Gale Crater, Mars, using the frequent joint atmospheric observations of the orbiting Mars Climate Sounder (MCS) and the Mars Science Laboratory Curiosity rover. Using these data and an estimate of planetary boundary layer (PBL) depth from the MarsWRF general circulation model, we divide the vertical column into three regions. The first region is the Gale Crater PBL, the second is the MCS-sampled region, and the third is between these first two. We solve for a well-mixed dust mixing ratio within this third (middle) layer of atmosphere to complete the profile. We identify a unique seasonal cycle of dust within each atmospheric layer. Within the Gale PBL, dust mixing ratio maximizes near southern hemisphere summer solstice (L-s=270 degrees) and minimizes near winter solstice (L-s=90-100 degrees) with a smooth sinusoidal transition between them. However, the layer above Gale Crater and below the MCS-sampled region more closely follows the global opacity cycle and has a maximum in opacity near L-s=240 degrees and exhibits a local minimum (associated with the solsticial pause in dust storm activity) near L-s=270 degrees. With knowledge of the complete vertical dust profile, we can also assess the frequency of high-altitude dust layers over Gale. We determine that 36% of MCS profiles near Gale Crater contain an absolute high-altitude dust layer wherein the dust mixing ratio is the maximum in the entire vertical column.

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