Diurnally Forced Tropical Tropospheric Circulation over South America

摘要

The impact of diurnally varying thermal forcing on the tropical circulation is studied with a linearized shallow water model on an equatorial beta plane. The mass and flow fields are interpreted as internal modes of a stratified model, based on the results of the projection of typical cumulus heating profiles. The projection of referred profiles is optimally described by a convergence/divergence pattern at high/low levels in the tropics with an equivalent depth on the order of 220 m. The effect of altering the size, latitude and internal mode representation of a bell shaped mass source is considered in terms of the energy partition between Kelvin, mixed Rossby-gravity and gravity intertial waves and Rossby waves. The 500 mb vertical motion fields associated with the diurnal evolution of the oscillatory solution are compared to those derived from the National Meteorological Center final Analysis over the tropical South America.