Anomalous Dynamics of Bottom Currents and Temperature in the Northeastern Sector of the Middle Caspian Sea

Abstract

The results of an investigation into water mass dynamics in the northeastern sector of the middle Caspian Sea are presented. High variations of currents are observed in this region of the sea, which are caused by the influence of the Peschanomysskoye Rise (PMR) on the cyclonic gyre. This bottom elevation is an obstacle to the currents of the gyre. The Yuzhno-Buzachinskii Deflection also influences the currents. Part of the dense and cold waters from the northern Caspian Sea flows along this deflection to the Derbent Basin. This basin is also a sink for the cold waters transported on the Peschanomysskoye Rise and those that overflow it. Observations in May 2015 over a cross-shaped survey at the western basement of the PMR showed that the currents in May in the western part of the survey in the entire water column from the surface to the bottom are organized in layers in the form of an anticyclonic spiral: the bottom current is directed to the south, the middle current is directed to the west, and the surface current is directed to the north. Lenses of warm water are observed in the bottom layer.