Does the present-day wind regime explain the location and geomorphology of dunes in the southern highlands of Mars?

Details Does the present-day wind regime explain the location and geomorphology of dunes in the southern highlands of Mars? Does the present-day wind regime explain the location and geomorphology of dunes in the southern highlands of Mars?

Dec 2004

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004agufm.p22a..05f&link_type=abstract

American Geophysical Union, Fall Meeting 2004, abstract #P22A-05

Physics

5415 Erosion And Weathering, 3329 Mesoscale Meteorology, 3346 Planetary Meteorology (5445, 5739), 3307 Boundary Layer Processes, 1625 Geomorphology And Weathering (1824, 1886)

Scientific paper

Dozens of dunefields are scattered throughout the southern highlands of Mars, mostly (but not entirely) located in the floors of impact craters. MOC Narrow Angle images reveal that these dunes are not basic barchan or transverse in form, but rather that they are a combination of barchans, reversing, linear, and star dunes, indicating that they were formed in a multi-directional wind regime. In Noachis Terra, west of Hellas Planitia, almost all dunefields show three dominant slipface orientations, indicating formative winds from the SW, SE, and NE. Different dunefields show these three winds in different proportions, suggesting that in different areas, different winds have dominated. To determine how these different winds interact in the present day wind regime, we ran the Mars MM5 over Noachis Terra. The model runs include twelve 10-day runs spaced throughout the martian year, with a grid size of 20 km and a timestep of 10 seconds (physical parameters were saved once every hour). Winds from the SW blow during winter afternoons, caused by geostrophic forcing. Because of coverage from the seasonal polar cap, these winds are more effective in blowing sand at latitudes poleward of 50° S, roughly consistent with the observed spatial pattern in dune morphology. Winds from the SE blow during the early to mid afternoon in the spring, caused by slope winds blowing up and over the rim of the Hellas basin. These winds should be more common closer to Hellas Planitia, but they appear in dunes throughout Noachis Terra. Winds from the NE blow in the evening during summer, and they are katabatic flows that accelerate into topographic lows, following the diurnal tide. These winds are strongest equatorward of 50° S, which is fairly consistent with observed dune morphology. Discrepancies between the model and observed dune slipfaces can be explain by shifting physical parameters (i.e., dust loading or obliquity).

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