Geophysical Research Letters, in press.

Multiple equilibria in a single-column model of the tropical atmosphere.

Adam H. Sobel
Department of Applied Physics and Applied Mathematics and Department of Earth and Environmental Sciences, Columbia University, New York, NY.

Gilles Bellon
Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY.

Julio T. Bacmeister
Goddard Earth Sciences and Technology Center, University of Maryland, Baltimore County, Baltimore, MD.

Abstract

A single-column model run under the weak temperature gradient approximation, a parameterization of large-scale dynamics appropriate for the tropical atmosphere, is shown to have multiple stable equilibria. Under conditions permitting persistent deep convection, the model has a statistically steady state in which such convection occurs, as well as an extremely dry state in which convection does not occur. Which state is reached depends on the initial moisture profile.