Some computations of surface air trajectories over the oceanic tropics and accompanying weather

Abstract

An attempt is made to compute some near surface air trajectories from an initial specification of the (steady) pressure field over selected regions of the oceanic tropics: Friction is assumed to oppose the motion and is proportional to the speed, while the percentage change of horizontal areas is computed to obtain the horizontal velocity divergence along the parcel paths. The latter results are related to observed distributions of low-level cloudiness and rainfall in the Indian Ocean and selected regions of the Pacific. Further interpretative comment is offered through an analysis of the divergence equation; the latter indicates that both the divergence of the pressure-gradient force and Coriolis forces are significant in determining the temporal change of horizontal velocity divergence along a trajectory.