SHARAD Observations of Temporal Variations of CO2 Ice Deposits at the South Pole of Mars

Abstract

Mars’s polar regions are covered by kilometers-thick layered deposits which carry a record of the planet’s climate history. The deposition and volatilization of the shallow CO2 deposits in the south pole have a large impact on the planet’s atmosphere and environment. This research focuses on the timing variation of the thickness of the shallow deposits based on the SHARAD data collected from the past 11 terrestrial years, and analysis of the contributing factors based on the volatilization and deposition mechanisms of surface and subsurface materials. In this work, we selected more than four thousand data points, covering several seasons and Martian years, to extract radar echoes and calculate the thickness changes in the subsurface layer over time. We found that the thickness of the CO2 layer becomes thinner in the summer, with seasonal variation in the range of ~16–45 m. The thickness variations have a Gaussian-like distribution and do not increase with the distance between the compared node pair, implying that the phenomenon is not caused by regional differences. The overall thickness within the 11 terrestrial years does not show a clear trend of thickening or thinning, indicating a moderate vertical change of the southern deposits.