Quantification of summertime water ice deposition on the Martian north polar ice cap

TL;DR

This study uses CRISM observations to quantify water ice deposition on the Martian north polar cap during summer, revealing grain size cycles and estimating water ice transport, with implications for Martian water cycle understanding.

Contribution

First to monitor the complete spring to summer water ice grain size cycle on Mars' north polar cap and quantify summer water ice deposition.

Findings

Water ice grain sizes grow until Ls=132 then shrink.

Quantified water ice deposition during summer (0.7-7 microns).

North polar summer deposition comparable to south polar summer deposition.

Abstract

We use observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) of the north polar cap during late summer for two Martian years, to monitor the complete summer cycle of albedo and water ice grain size in order to place quantitative limits of the amount of water ice deposited in late summer. We establish here for the first time the complete spring to summer cycle of water ice grain sizes on the north polar cap. The apparent grain sizes grow until Ls=132, when they appear to shrink again, until they are obscured at the end of summer by the north polar hood. Under the assumption that the shrinking of grain sizes is due to the deposition of find grained ice, we quantify the amount of water ice deposited per Martian boreal summer, and estimate the amount of water ice that must be transported equatorward. Interestingly, we find that the relative amount of water ice deposited in the north cap during boreal summer (0.7-7 microns) is roughly equivalent to the average amount of water ice deposited on the south polar cap during austral summer (0.6-6 microns).