IDENTIFICATION OF FORMATION MECHANISMS OF INDIAN OCEAN DIPOLE
The purpose of this work is to clarify the characteristics of Rossby waves and the parameters of the critical layer in the Indian Ocean. In this layer, the phase velocity of Rossby waves is equal to the average velocity of zonal flows and generation of growing disturbances is possible. They are the internal Indo-oceanic mode, not related to the events of the El Niño-South oscillation. In the present work the operative reanalysis ORAS5 data of European Centre for Medium-Range Weather Forecasts (ECMWF) on potential temperature, salinity, and the zonal component of the current velocity for the period 1979 - 2018 were used. For each month, the magnitude of the phase velocity of the first baroclinic mode of the planetary waves and the average values of the velocities of zonal currents were calculated. It is shown that the critical layer is formed in the vicinity of 49 - 50°E and 11 - 13°S at a depth of 0 - 500 m.