Observations by MRO/MARCI show seasonal and interannual variability.
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Retreat of high albedo material over Gemini Scopuli is annually repeatable.
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Changes for other areas are variable between years and over northern summer.
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Observations suggest retreat of late water ices followed by removal of dust lags.
Abstract
The MARCI camera on the Mars Reconnaissance Orbiter provides daily synoptic coverage that allows monitoring of seasonal cap retreat and interannual changes that occur between Mars year (MY) and over the northern summer. The northern seasonal cap evolution was observed in MY 29, 30 and 31 (12/2007–04/2012). Observation over multiple Mars years allows us to compare changes between years as well as longer-term evolution of the high albedo deposits at the poles. Significant variability in the early season is noted in all years and the retreating seasonal cap edge is extremely dynamic. Detailed coverage of the entire seasonal and residual ice caps allows a broader view of variations in the high albedo coverage and identifies numerous regions where high albedo areas are changing with time. Large areas of disappearance and reappearance of high albedo features (Gemini Scopuli) are seasonally cyclical, while smaller areas are variable on multi-year time scales (Abalso Mensae and Olympia Planitia). These seasonal and interannual changes directly bear on the surface–atmosphere exchange of dust and volatiles and understanding the current net processes of deposition and erosion of the residual ice deposits. Local and regional variation in high albedo areas reflects an interplay between frost deposition, evolution, and sublimation along with deposition and removal of dust.
