LONG-TERM SEA LEVEL VARIABILITY IN THE SOUTHERN CASPIAN SEA

At the border of Asia and Europe, the Caspian Sea (CS) is the world’s largest inland basin. Coastal regions of southern CS experience different types of sea level fluctuations. The timescale of these fluctuations vary from hours to months and years. In this study a good understanding of the Caspian Sea level (CSL) variation is reached through both field observation and numerical modeling. The CSL variation is due to various factors; these fluctuations could be divided into long-term and short-term categories. The long term CSL variability depends on sea water balance and is dominated by Volga river discharge. The other contributing components for this type of CSL variability include surface evaporation, precipitation, discharge to Kara Bogaz Gol bay and ground water input/output. The next category is short-term CSL variability which is caused mostly by the effect of wind, waves, atmospheric pressure, and tide. These fluctuations have the time scales less than 2-3 days, but the long-term CSL variability acts as seasonal and inter-annual variation. The following figure shows the seasonal CSL cycles from 2009 to 2011 in a coastal station in the southern region of the CS. The reason for sea level rise in the summer times is the higher rivers’ discharge which is mostly flows into the CS by Volga River.