Upwelling events in the Caspian Sea

Abstract

In this article, upwelling phenomena that are observed in the surface waters of the Caspian
Sea were studied. For this purpose, we used data from MODIS-Aqua satellite observations in
the infrared range of 11 microns, with a spatial resolution of 4 km, for the period 2003-2021,
which are available through the NASA Giovanny on-line data system databases. It has been
established that in the eastern part of the Middle and South Caspian, upwelling phenomena
are mainly observed from May to September. The most intense upwelling is observed on the
eastern coast of the Middle Caspian in July-August. According to averaged long-term data, the
upwelling phenomenon during this period is mainly observed between 40-44º latitude, and
its width increases from north to south, reaches 60-70 km in the direction of the Kazakh Gulf
and decreases to the south. In the upwelling zone, the temperature gradient sometimes
reaches 4.0ºС/100 km. In some years, the upwelling zone that has arisen on the eastern coasts
can spread over long distances and even reach the western coasts. In most cases, the upwelling
phenomenon occurs against the background of advection of warm waters from the South
Caspian to the Middle Caspian.