On the interpretation of the Gill model.

J. David Neelin

J. Atmos. Sci., 1989, vol.46, 2466-2468.
© Copyright 1989 by the American Meteorological Society.

Abstract. The simple model of tropical atmospheric circulation put forward by Gill (1980) has come into widespread use for studies of tropical air-sea interaction. Gill motivates the model in terms of internal modes of an atmosphere with a lid, forced by diabatic heating. For models of tropical air-sea interaction, it is necessary to parameterize this forcing in terms of the sea surface temperature (SST) in some fashion. In the model of Lindzen and Nigam (1987) boundary layer temperatures are strongly tied to SST by turbulent vertical mixing. They introduce a term which they refer to as the 'back-pressure' effect. When this term is included, they point out that their model resembles the Gill model but with the forcing in the momentum equations rather than in the height equation, and with a very much larger damping coefficient in this equation than in Gill's version. The present author indicates that the analogy to the Gill model can be extended to include the forcing term and to discuss the implications of this for interpretation of the atmospheric side of the tropical air-sea coupling problem.