Impact of water mass forcing on the general circulation model simulations

Abstract

The mass continuity equation traditionally used in atmospheric models does not take into account the local sources and sinks. The mass of the atmosphere varies due to the moisture variation arising from evaporation and precipitation. Evaporation and precipitation are the local sources and sinks of atmospheric mass. So far, almost all models do not include this effect of moisture variation on atmospheric mass and instead only adjust the virtual temperature. This leads to an inconsistency in the model formulation.

In the present study, we have incorporated the effect of moisture variation into the mass budget equation of the NCAR CCM2 General Circulation Model. This is called Water Mass Forcing (WMF). The present study is exploratory in nature. We have found that WMF has significantly modified the climate of the tropics. In particular, the precipitation and wind simulations for the Indian summer monsoon have improved substantially