Investigating Temporal and Spatial Caspian Sea Level Changes Between 1992 and 2011, Using Satellite Altimetry Data of T/P, Jason1 and Jason2

To investigate Caspian Sea level changes, sea surface height (SSH) data obtained from satellite altimeters, Topex/Poseidon, Jason1 and Jason2, between 1992 and 2011 were used. The data between 1992 and 2002 were obtained from T/P, between 2002 and 2008 were obtained from Jason1, and between 2008 and 2011 were obtained from Jason2. Finally, in almost 19 years, 9 passes and in average over each pass 680 cycles of data have been observed. According to this fact that the orbit of these satellites in the mentioned years are the same, time series for the points over passes have been produced. Time series on points over passes and in the crossover of passes have been produced and Least Squares Spectral Analysis have been performed on them. For further comparison and investigation of Caspian Sea level changes, tide gauge records in Neka and Anzali stations have been used. The correlation coefficient between tide gauge time series of Neka and the altimetry time series of one point on Caspian Sea were calculated 0.6663 and for tide gauge time series of Anzali and the altimetry point, correlation coefficient was 0.8198. Between Neka and Anzali, correlation coefficient was 0.7919. Spectral analysis on these time series showed a period of 1 year over all of them. Some of periods such as 6.7 years have been observed in Neka and altimetry that they didn’t exist in Aanzali, that there is no physical justification for them. Between 1992 and 2011 Caspian Sea level dropped about 2.5 cm per year.