Seasonal patterns of condensation and sublimation cycles in the cryptic and non-cryptic regions of the South Pole

Abstract

The South Pole of Mars is characterized by an asymmetric residual ice cap composed of water ice and CO 2 ice. On the opposite side of the residual cap, there exists an area called cryptic region which is relatively free of ice during summer time. Many fan-shaped km-scale structures apparently caused by a wind-blown system of dust-laden gas jets occurred dozens degrees of Ls before the complete sublimation of the CO 2 frost layer. We have examined the seasonal cycles of condensation and sublimation in the cryptic and non-cryptic regions by using the topographic data from the MOLA/MGS measurements. Using the MOLA topography data collected over one Martian year (1999–2001), we have studied the temporal elevation change and the seasonal cycle of the carbon dioxide frost on the southern polar caps. We have produced mapping of the seasonal CO 2 frost thickness variation for seven Ls (30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270° and 330°). It is found that the time variations of the CO 2 frost thickness in these two regions are quite similar. The greatest thickness of the CO 2 frost layer is about 0.76–0.78 m in both places occurs at Ls = 150°.