Structure of a Tropical Disturbance Based on Solutions of a Multilevel Baroclinic Model

Abstract

Vertical motions in the tropics are computed for an easterly wave perturbation associated with an upper tropospheric cold core low. The winds are deduced from the pressure field by solving a five level non-geostrophic model on the IBM 7094. The streamlines exhibit the well known properties of vortex and col points and agree quite well with the observed wind observations at the various levels. Vertical motions show the dynamical and thermodynamical interaction of the lower and upper level phenomena. Typical magnitudes of the vertical motion are around 1/10 cm sec?1. Differential vertical advection and the Laplacian of thermal advection by the rotational component of the wind contribute significantly to these organized vertical motions.