Numerical simulation of the forcing of monsoon surges by mid-latitude baroclinic waves

Abstract

A global, six-level, primitive equation model was numerically integrated to examine the interaction of a mid-latitude baroclinic wave with several different mountain-valley configurations. The purpose was to determine the contribution of a well-developed baroclinic wave to the initiation of a monsoon surge. It was found that these waves can initiate a surge. Such surges are weak and limited in extent but they do exhibit the characteristics of observed monsoon surges. The latitudinal location of the east-west mountain range has a large impact on the strength of the disturbance and thus on the initiation of the surge. However, the size of the valley is not an important consideration. The surge is strongest at the lowest levels and dissipates rapidly with height. Overall results indicate surge forcing by the baroclinic wave is possible but other forcing mechanisms are necessary in order to simulate the stronger, more extensive surges observed during the winter monsoon.