Wind-Enhanced Interaction of Radiation and Dust (WEIRD) and the Growth and Maintenance of Local Dust Storms on Mars
| Autor: | Rafkin, Scot C. Randell |
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| Rok vydání: | 2011 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | A radiative-dynamic positive feedback mechanism (Wind Enhanced Interaction of Radiation and Dust: WEIRD) for localized Mars dust disturbances was previously found to operate in highly idealized numerical experiments. Numerical simulations are used to test for the presence and quantitative effect of the radiative-dynamic WEIRD feedback mechanism under more realistic conditions. Comparisons between cases where lifted dust is radiatively active and radiatively passive elucidate the importance of the dust radiative forcing on the thermodynamic and kinematic structure of the atmosphere. The WEIRD feedback mechanism does operate under realistic conditions, although it can be masked and diminished by a variety of other forcing mechanisms. Globally increased dust loading is found to accelerate the local winds while simultaneously diminishing the impact of local physiographical forcing. Local enhancements of dust produce a thermal and dynamical response that resembles many of the essential features seen in the idealized experiments. The development of a warm core low, rotational wind tendencies and convergence boundaries intersecting at the center of the strongest dust storms are consistent with WEIRD. Local and regional storms are effective at producing elevated dust layers above the boundary layer aided by the radiative forcing of the dust. Ubiquitous and persistent thermal circulations associated with topography can also inject dust into the free atmosphere above the planetary boundary layer, but they are less efficient than the dust storms. High concentrations of dust in the lowest levels of the atmosphere produce a significant and dramatic heating of the ground and the near-surface air despite greatly reduced insolation at the surface. Comment: 15 pages, 13 figures |
| Databáze: | arXiv |
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