Caspian sea level from Topex‐Poseidon altimetry: Level now falling

Tide gauge measurements recorded between 1978 and 1993 indicate that the Caspian sea level (CSL) has been rising at an average rate of ∼12 cm/yr during this 15‐yr time span. Decadal CSL changes are currently attributed to changes in river runoff and effective evaporation. We have analysed three and a half years (from January 1993 through August 1996) of altimeter range data from the TOPEX‐POSEIDON mission over the Caspian sea to estimate temporal variations in the sea level. We show that the Caspian sea level was still rising at a rate of 18.9±0.5 cm/yr between January 1993 and July 1995 and that the northwestern Caspian in the area of the Volga delta was rising faster (by ∼3 cm/yr) than the middle and south Caspian. However, by mid‐1995, the CSL started to drop abruptly, a trend still observed in 1996. The average sea level decrease recorded from mid‐1995 amounts to −24.8±1.4 cm/yr.

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