![]() ![]() These cold drainage winds are analogous to those on the terrestrial Antarctic cap. Strong katabatic winds occur on the north polar cap, producing widespread frost streaks. A prominent role for eolian processes in the formation of all of these features is proposed. The major topographic features of the martian polar layered deposits include the conspicuous spiral troughs, subtle undulations, broad reentrants (chasma), steep, arcuate scarps, and dune fields. Finally, we use Froude and geometrical analysis to estimate the rate of upstream migration caused by katabatic winds for the spiral troughs. We then devise a theoretical framework for understanding the origin of the spiral troughs that agree with 10 criteria that should be explained for any scenario to satisfactorily model the spiral troughs. ![]() We examine visible images from the Thermal Emission Imaging System and observe low-altitude clouds that we interpret to be the result of katabatic jumps, i.e., the Aeolian counterpart of hydraulic jumps in open channel flow. ![]() We use radar stratigraphy from the Shallow Radar instrument on Mars Reconnaissance Orbiter to examine trough evolution and constrain lateral transport. The repeating pattern is bounded by hydraulic jumps, which act to stabilize the form. Cyclic steps are quasi-stable, repeating, and upstream-migrating bed forms that have been studied in terrestrial and submarine environments. We combine observations of stratigraphy, morphology, and atmospheric processes to relate the spiral troughs on Mars' polar layered deposits to a class of features known as cyclic steps. ![]()
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