During the southern polar cap’s recession (Ls = 180–270°), the seasonal south polar cap retreats continuously and asymmetrically around the geographic pole, leaving a prominent albedo feature on the seasonal cap that appears almost as dark as bare ground, yet remains cold (−135 °C) because there is a thick layer of CO2 ice under an opaque dust cover. The region occupies the same area year by year (Titus et al. 2003).
The low albedo of the material cover in the cryptic region indicates that a large fraction of the solar radiation is being absorbed in or beneath (Kieffer 2000) the surface.
When the Sun rises seasonally, temperatures remain near the CO2frost point, but albedos slowly increase initially and then drop...
- Kieffer HH (2000) Annual punctuated CO2 slab-ice and jets on Mars. The second international conference on Mars polar science and exploration, Reykjavik, Iceland #4095Google Scholar
- Kieffer HH (2003) Behavior of solid CO2 on Mars: a real zoo. Sixth international conference on Mars, Pasadena, California #3158Google Scholar
- Titus TN, Kieffer HH, Plaut JJ, Christensen PR, Ivanov AB, et al (2003) South polar cryptic region revisited: themis observations. Third Mars polar science conference, Alberta, Canada #8081Google Scholar