Dynamics in planetary Atmospheric physics: comparative studies of equatorial superrotation for Venus, Titan, and earth

he long-standing problem of equatorial superrotation in a slowly rotating planetary atmosphere has been solved recently. This article presents a systematic, comprehensive, and analytical examination of the momentum budget that maintains stable superrotational winds in a given planetary atmosphere. After reviewing general approaches used in modeling comparative planetary atmospheres, i describe the major dynamical processes that maintain stable equatorial superrotation for the atmospheres of Venus, saturn’s moon Titan, and earth. under appropriate conditions, all three bodies could have equatorial superrotational winds greater than 100 m s21. Venus’ equatorial superrotation of 118 m s21 is maintained at its cloud-top level at ≈65 km. my model predicts that, to maintain an equatorial superrotational jet stream in Titan’s stratosphere, its main haze layer, which absorbs solar radiation, would need to be centered at an altitude of 288 km (corresponding to 10 pa pressure). it is hoped that ongoing observations by the cassini-huygens mission to saturn will be able to validate this model prediction. strong equatorial superrotational winds could also be induced on earth by optically thick dust clouds, such as those arising from an asteroid impact or extreme volcanic event. superrotation would greatly enhance meridional transport in the earth’s atmosphere, which could have accelerated the globalization of an environment unfavorable to the survival of the dinosaurs.