Thermohaline Contribution of the Caspian Sea Water Dynamic

Abstract

This article investigated the principal reason for water circulations in the Caspian Sea. Unlike other inland water bodies, and similar to the open seas, the Caspian Sea shows regular water circulations which are not explained by the wind. The Steric contribution of water level fluctuations was studied in this article by two approaches: one from remote sensing and climatology data, and the other, from space altimetry and gravimetry data. The approaches are fundamentally different: the first approach directly observes and measures the steric fluctuations, while, the second approach estimates the steric fluctuations by analysing their causing factors such as water temperature and salinity. Analysis of over 13 years data showed that estimations from these two approaches are consistent. Based on the results, the Steric Sea Level (SSL) included a seasonal cycle of about 8.5 cm and a seasonal topography of 4 and 7 cm in winter and summer respectively. The seasonal water circulations observed in the lake was consistent with the geostrophic response to estimated steric topography. Moreover, the results demonstrated that the seasonal water surface topography is the reason for water circulation in the Caspian Sea.