A Simplified Model for Precipitation Fronts in the Tropics

Samuel Stechmann, New York University

In models for atmospheric weather and climate, convection plays a major role, especially in the tropics. Convection draws in moist air near the ocean surface and carries it upward several kilometers. The water vapor in the air then condenses to liquid water, and the heat released from this process can further drive atmospheric motions. Convection and cloud formation, though, often occur at sub-grid scales for atmospheric models (known as general circulation models or GCMs). Therefore, their effects must be parameterized.

Since GCMs account for many atmospheric processes and are therefore very complex, it is not clear what kinds of waves are supported by their convective parameterizations. A simplified tropical climate model can be used to isolate the effect of the convective parameterization. We show what kinds of precipitation fronts arise in such a situation for a common convective parameterization used in GCMs. Analytical solutions will be shown for a simplified case, and numerical results will be shown for more complex situations. The computations are done using an essentially non-oscillatory (ENO) scheme, which is able to resolve the front structure.

Abstract Author(s): Samuel N. Stechmann and Andrew J. Majda