caspian sea level survey with grace and grace-fo

The caspian sea is bordered by iran, russia to the north, russia and the republic of azerbaijan to the west, and the republics of turkmenistan and kazakhstan to the east. the northern part of the caspian sea is very shallow. caspian sea level (csl) has been declining in recent years. in this research, gravimetric satellites have been investigated for csl. the rate of decrease of the caspian sea is 3.87 cm/year. the results also show that the decrease in csl in the north compared to the center and south is almost half, which needs further investigation.