Effects of Global Dust Storms on Water Vapor in the Southern Polar Region of Mars.

Martian global dust storms (GDS) can significantly affect the water cycle in the lower atmosphere (0−40 km). We compare the evolution of water vapor abundances, dust opacity and surface temperatures in the Southern Polar Region (SPR) during GDS years of MY25, MY28, and MY34 relative to years without GDS. During all GDS years, the vapor abundances decrease in the lower atmosphere in the SPR following the storm. Our results suggest that this decrease could be the result of disruption of the southward transport of vapor by atmospheric circulation. Alternatively, the decrease in vapor abundances could be caused by decreased desorption of vapor from the subsurface. Plain Language Summary: This work presents comprehensive analysis of how water vapor in the Martian polar atmosphere reacts to large dust storms in different years. Measurements of water vapor, atmospheric dust, and surface temperatures collected by different spacecraft instruments in years with and without large dust storms are compared. These comparisons inform our understanding of how Martian water vapor is transported through the atmosphere and how it interacts with the surface. Large dust storms decrease the amount of water vapor in the southern polar region. This may indicate that the transport of vapor to the pole is reduced by the storms, or that dusty atmosphere cools the surface and reduces the amount of vapor released from the subsurface. Key Points: Water vapor abundances over the Southern Polar Region of Mars are reduced following a global dust storm (GDS)The decrease in water vapor abundances could be caused by disruption of southward vapor transport by a GDSAlternatively, the decrease could be caused by changes in the surface‐atmosphere vapor exchange [ABSTRACT FROM AUTHOR]