The Nonlinear Response of a Slowly-Rotating Atmosphere to Mobile Heating : Numerical Experiments of Relevance to the Venusian Atmosphere

Abstract

The three-dimensional response of a slowly-rotating atmosphere to mobile heating is investigated by using a multi-layer primitive equation model on the sphere. The velocity of planetary rotation and that of solar heating are fixed at the values of Venus. The global circulation is assumed to be induced only by the solar radiation absorbed by the ground. The global circulation induced in this way can produce an atmospheric stability by the upward heat transport. In order to examine this nonlinear effect, the model is numerically integrated from a state of neutral stratification. It is found that the direct circulation between the day and night sides predominates always for standard parameter values. The temperature maximum point on the equator is deviated from the subsolar point by 60°. The horizontal temperature contrast between the day and night sides is very small(0.16K in the lowest layer). The atmospheric stratification produced by the global circulation is also too weak even in the night side. In the experiments with one solar day assumed to be 1/2 or 1/4 of Venus' solar day(117 days), the zonally uniform meridional circulation appears in place of the direct circulation.