The Caspian Sea level forced by the atmospheric circulation, as observed and modelled

Abstract

The Caspian Sea Level (CSL) has experienced large fluctuations with wide-reaching impacts on the population on the coastal regions and on the economy. The CSL variability is dominated by the variability of precipitation over the Volga River basin. The precipitation during summer plays a dominant role and can explain the two major events that happened in the 1930s (drop) and after 1977 (rise). Impacts are expected from global warming due to enhanced greenhouse gas concentrations; especially the precipitation over the Volga River basin is expected to increase. It is, however, compensated more or less by increased evaporation over the Caspian Sea (CS) itself. It is shown that the Max Planck Institute for Meteorology (Hamburg) models are able to simulate most processes relevant for the CSL variability quite realistically, i.e., within the uncertainty of observational data. The simulations suggest a slight increase of the CSL in the 21st century; but due to a large variability of precipitation over the Volga River basin a statement concerning the future development of the CSL cannot be made with confidence at the moment. r 2007 Elsevier Ltd and INQUA. All rights reserved.