Moisture-coupled travelling waves for a simplified tropical climate model

The interaction of water vapor and planetary scale dynamics has a strong impact on predictions of weather and climate in the midlatitudes. However, general circulation models (GCMs) cannot currently resolve or parametrize these interactions adequately on the long time scales needed for seasonal (or longer) predictions. A simplified tropical climate model was recently developed by Freierson, Majda, and Pauluis (2004) to study the interaction of moisture and large scale dynamics. This presentation describes moisture-coupled travelling wave solutions for the simplified tropical climate model of Freierson et al.

The waves are moisture-coupled in the sense that the front is the boundary between a dry region and a precipitating region. These waves are allowed to belong to three families, classified by the allowed front speeds: fast drying fronts, and slow and fast moistening fronts.

Four model parameters interact to determine the slope of the front: the front speed, the background mean moisture gradient, the convective adjustment time, and another parameter related to the precipitation parametrization. Choices of model parameters which lead to physically (un)reasonable front slopes will be discussed.