In:
Journal of Geophysical Research: Planets, American Geophysical Union (AGU), Vol. 100, No. E12 ( 1995-12-25), p. 26357-26376
Kurzfassung:
We present results from the first numerical simulations of simultaneously evolving three‐dimensional thermal, dynamical, and radiatively active suspended dust fields in the Martian atmosphere. Simulations of southern summer dust storms (arising from a prescribed southern subtropical surface dust source) conducted with a Mars general circulation model (GCM) illustrate the important role of dust transport by atmospheric eddies. Both traveling and stationary eddies contribute to dust transport to high latitudes in both hemispheres. These hemispheric differences arise from seasonal and topographic effects. Transport into the south polar regions is accomplished primarily by thermally and topographically forced standing eddies. Both traveling and stationary eddies transport dust to middle and high northern (winter) latitudes. Atmospheric wave motions are affected by the developing storms. Thermal tidal amplitudes increase at storm onset, with the calculated pressure response at a model grid point corresponding to the location of the Viking Lander 1 site in good agreement with observations. In qualitative agreement with observations, winter hemisphere baroclinic waves weaken during the early stages of the storm, but as the storm wanes, amplitudes of these waves increase. A slowly westward propagating (9 degrees of longitude per sol) zonal wavenumber one feature in the temperature and geopotential fields at middle northern latitudes amplifies rapidly during the initial sols (Martian solar days) of the simulated storms. This feature is suggestive of the observed north polar warming which occurred during the 1977B global dust storm, but the simulations produce a much weaker polar warming (∼10 K at 0.5 mbar) than was observed (40–50 K). The globally integrated CO 2 condensation rate decreases by 15–20% during the simulated dust storm onset and would likely be decreased more if a stronger polar warming were produced. During the initial stages of the simulated storms, surface stress values in the southern subtropics intensify due primarily to the intensification of the Hadley circulation and thermally driven tides. This supports the hypothesis that these components of the general circulation contribute strong positive feedbacks to the developing storms.
Materialart:
Online-Ressource
ISSN:
0148-0227
Sprache:
Englisch
Verlag:
American Geophysical Union (AGU)
Publikationsdatum:
1995
ZDB Id:
2033040-6
ZDB Id:
3094104-0
ZDB Id:
2130824-X
ZDB Id:
2016813-5
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2016810-X
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2403298-0
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2016800-7
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161666-3
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161667-5
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2969341-X
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161665-1
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3094268-8
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710256-2
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2016804-4
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3094181-7
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3094219-6
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3094167-2
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2220777-6
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3094197-0
SSG:
16,13
