An Investigation of the Encirclement of Mars by Dust in the 2018 Global Dust Storm Using the Ensemble Mars Atmosphere Reanalysis System (EMARS)

Abstract:

Abstract

One key challenge of Martian meteorology is understanding the formation and growth of global dust storms. We use the Ensemble Mars Atmosphere Reanalysis System (EMARS), which is a combination of Mars Climate Sounder observations and a Mars global climate model, to simulate the 2018 global dust storm. The incorporation of temperature and dust observations into EMARS provides a connection with the behavior of the real Martian atmosphere not found in models, while the model extends the sparse observational information into full 4D fields, including unobserved fields like the winds, which are crucial in assessing advection of dust. We investigated the early encirclement of Mars by dust during the 2018 dust storm, particularly near Ls 189.6, or seven sols after the first signs of the storm we identified in global dust climatology. Early on in the storm's development, a major lifting center of dust was present in Chryse Planitia and Arabia Terra, near the location of the Opportunity rover, and dust was observed to encircle the northern hemisphere of Mars. We found that, at 3 PM local time, upward vertical winds near the equator, over Chryse and Arabia, were both closer to the surface and greater in magnitude during the global dust storm than at the same time two years before. We examined where atmospheric dust above Chryse and Arabia would go if advected using EMARS winds starting on this sol, and we found that it encircled the northern hemisphere of Mars after 5 sols. We also investigated the role of lifting compared to advection in the encirclement of the northern hemisphere of Mars by dust, and we found that while both contributed, the relative contributions of advection and lifting depended heavily on how the region of encirclement was defined.

Acknowledgments

This research was supported by the NASA Mars Data Analysis Program grant 80NSSC17K0690. EMARS data from before MY 34 is available from the Penn State Data Commons at https://doi.org/10.18113/d3w375.