Velocity of propagation of temperature anomalies in the tropical zone of the Indian Ocean

We describe the space-and-time structure of large-scale thermal anomalies in the upper layer in the tropical zone of the Indian Ocean and study the mechanism of their formation. It is shown that the critical layer in which the phase velocities of propagation of disturbances coincide with the mean velocity of the zonal current can be formed in the central part of equatorial zone of the Indian Ocean (between 9° and 12°S). In this layer, the formation of growing disturbances is possible due to the barotropic-baroclinic instability of the system of zonal currents.