The role of seasonal reservoirs in the Mars water cycle: II. Coupled models of the regolith,the polar caps,and atmospheric transport |
| |
| Authors: | Bruce M Jakosky |
| |
| Institution: | Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA |
| |
| Abstract: | The behavior of water vapor in the Mars atmosphere requires that there be a seasonally accessible nonatmospheric reservoir of water. Coupled models have been constructed which include exchange of water with the regolith and with the polar caps, and transport through the atmosphere due to its circulation. Comparison of the model results with the vapor observations and with other data regarding the physical nature of the surface allows constraints to be placed on the relative importance of each process. The models are capable of satisfactorily explaining the gross features of the observed behavior using plausible values for the regolith and atmosphere mixing terms. In the region between the polar caps, the regolith contributes as much water to the seasonal cycle of vapor as does transport in from the more-poleward regions, to within a factor of 2. Globally, 10–40% of the seasonal cycle of vapor results from exchange of water with the regolith, about 40% results from the behavior of the residual caps, and the remainder is due to exchange of water with the seasonal caps. It is difficult to determine the relative importance of the processes more precisely than this because both regolith and polar cap exchange of water act to first order in the same direction, producing the largest vapor abundance during the local summer. The system is ultimately regulated on the seasonal time scale by the polar caps, as the time to reach equilibrium between the atmosphere and regolith or between the polar atmosphere and the global atmosphere is much longer than the time for the polar caps to equilibrate with the local atmosphere. This same behavior will hold for longer time scales, with the polar caps being in equilibrium with the insolation as it changes on the obliquity time scale, and the atmosphere and regolith following along. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
