Seasonal variability of circulation in the Caspian Sea reconstructed from normal hydrological data

Seasonal variability of climatic circulation in the Caspian Sea is examined from the reconstructed sea currents with the use of a three-dimensional model of sea dynamics based on the primitive equations of fluid dynamics. The reconstruction of three-dimensional currents is carried out by the method of fluid-dynamic adjustment. This work is based on the arrays of 12-month normal data on temperature and salinity computed from the data of 65 000 oceanographic stations. It is shown that the dynamics of sea currents is strongly affected by drift currents, by the interaction between the drift currents and the bottom topography, by the transport of water masses in both the horizontal and the vertical, and by local heat fluxes through the sea surface. The yearly average surface currents over the deep-sea parts of the middle Caspian Sea form a cyclonic gyre; however, because of high seasonal variability, the cyclonic character of large-scale circulation can be regarded only as qualitative information about surface currents.