An analytic model of the heat‐induced tropical circulation in the presence of a mean wind

A linear analytic model of the response of the tropical troposphere‐in the presence of a uniform zonal mean wind‐to an isolated region of deep heating is presented. the O(1) components of the response are the long Kelvin and planetary waves. as found in earlier work by Matsuno, Gill, and others. the behaviour of these modes is a function of a non‐dimensional parameter which combines the damping time, the wave speed, the mean wind speed, and the length of the heating region. It is interpreted as the ratio of the heating region length to the wave decay distance. When this ratio is small the response consists of long waves propagating away from the heating region. But when it is large, disturbances are locally determined at each longitude, and the dynamics are those of two‐dimensional Hadley circulations. In a westerly mean wind one also finds short stationary mixed and planetary waves downstream of the heating region. Their amplitude is small compared with the long waves, and proportional to U/LAH2 for small U, where U is the mean wind speed and LH the length of the heating region. In easterly mean winds the short stationary waves are replaced by inertial boundary layers at the edges of the heating region.