Computations of Surface Layer Air Parcel Trajectories and Weather in the Oceanic Tropics

This monograph develops a Lagrangian diagnostic scheme for large-scale frictional convergence in the boundary layer of the oceanic tropics using observed pressure and wind fields. The horizontal equations of motion, including Guldberg Mohn friction, are solved as an initial value problem for a constant Coriolis parameter, observed pressure gradients and initial winds during a one-hour period of integration. A variable Coriolis parameter is simulated by assigning a new value at each hour from computed values of the north-south coordinate. Examples are largely confined to mean distributions of pressure and wind in both Indian and Pacific oceans. Thus, a family of steady-state trajectories is determined for a given region.Various kinematical properties are computed, including horizontal divergence, and are interpreted diagnostically using the divergence equation. This analysis shows that the divergence of both Coriolis and pressure are equally important in determining the striking variations of horizontal velocity divergence along sample trajectories.The computed velocity divergence was found to compare favorably with observed distributions of mean cloudiness and rainfall in both Indian and Pacific oceans.The study will be of interest to meteorologists, physical oceanographers, climatologists, and physical geographers.