Orbit-spin coupling and the circulation of the Martian atmosphere

摘要

The physical origins of the observed interannual variability of weather andclimate on Mars are poorly understood. In this paper we introduce adeterministic physical mechanism that may account for much of the variabilityof the circulation of the Mars atmosphere on seasonal and longer timescales. Wederive a coupling expression linking orbital and rotational motions thatproduces an acceleration field varying with position and with time on andwithin a subject body. The spatially and temporally varying accelerations mayinterfere constructively or destructively with large-scale flows of geophysicalfluids that are established and maintained by other means. The hypothesispredicts cycles of intensification and relaxation of circulatory flows ofatmospheres on seasonal and longer timescales that are largely independent ofsolar forcing. The predictions of the hypothesis may be tested throughnumerical modeling. Examples from investigations of the atmospheric circulationof Mars are provided to illustrate qualitative features and quantitativeaspects of the mechanism proposed. We briefly discuss the implications andapplicability of the orbit-spin coupling hypothesis for planets other thanMars.