Multi-sensor analysis of water storage variations of the Caspian Sea

We perform a multi-sensor analysis of water storage and surface height variations of the Caspian Sea, from mid-2002 through 2006. Data from three satellite missions (GRACE, Jason-1, and Aqua) are used to examine the relationship between changes in spatially averaged sea surface height (SSH) and water storage in and around the Caspian Sea. Two composite time series are constructed to represent the mass change signal, the first by removing a model of nearby hydrological signals from the GRACE time series, and the second by subtracting a MODIS SST-based estimate of thermal expansion from the Jason-1 time series. The composite time series agree well (rms difference = 5.2 cm), and a positive trend is seen in both the GRACE (4.5 ± 0.7 cm/yr) and Jason (3.2 ± 0.3 cm/yr) composite time series. This analysis provides an indirect means of validating these data at regional spatial and monthly temporal scales.