The Caspian Sea Level and Rainfall in Northern Iran: Hydrological and Climatological Associations

The Caspian Sea that makes up a large portion of the northern border of Iran, is the world's largest lake in area and volume. The fluctuations of the Caspian Sea Level (CSL), particularly in their extreme conditions, have frequently hit the Iranian ports, residential infrastructures and disturbed the navigation system. The present study investigates the strength and temporal stability of the relationships between the CSL and three hydrological components comprising rainfall, evaporation and river discharges to the Sea. The status of the relationships during extreme phases of the sea surface temperatures (SSTs) was also studied. The SST data were considered as a climatological indicator influencing the CSL fluctuations. The study concluded that, during ordinary periods, the variations in hydrological variables are not accounted for a significant portion of variance in CSL. However, for the episodes that winter SSTs remains in the upper and lower 25% of all observed values, evaporation and runoff data, separately, account for a significant portion in CSL variations. The variations of SST data found to induce a significant impact in winter rainfall in Bandaranzali, Noushahr and their nearby regions.

کلیدواژه ها:

Caspian Sea ، sea level ، SST ، and extreme phase