Application of remote sensing techniques to understand the mechanisms behind the Caspian Sea lake-level fluctuations
The Caspian Sea has exhibited significantly wide range of water-level fluctuations in its history. The primary factor for these oscillations has been overwhelmingly ascribed to climate-induced variations; geologic-related processes have been suggested to be trivial and negligible. This work processed Topex\Poseidon data to estimate Lake-level heights for the Caspian Sea from the beginning of 1993 to August 2005. In order to improve the accuracy, the new Gravity Recovery and Climate Experiment orbits data, new Sea State Bias model, and Topex Microwave Radiometer drift correction were applied to the default altimetry data. The Caspian Sea hydrologic budget from 1998 to 2005 was also calculated using remote sensing and ground-based data. The National Center for Environmental Prediction Department of Energy Reanalysis 2 meteorological data provided all the variables necessary for the Penman method to estimate evaporation over the Caspian Sea. The Tropical Rainfall Measuring Mission rainfall data was utilized to estimate precipitation onto the Caspian Sea. This study reveals that lake-level changes from 1998 to 2005 are essentially controlled by meteorological factors based on the fact that a relatively minor difference between the water budget residuals and CSLL changes in the Caspian Sea. Moreover, the trend observed in the Caspian Sea lake level over the last several decades is closely correlated with Lake Van and Lake Urmia. However, the relatively higher dissimilarity present in 2000 and 2001 could imply that the Caspian Sea needs to lose some of its water to attain water balance. The two significant earthquakes with normal fault focal mechanisms and magnitudes of 6.8 and 6.5 Mw could be responsible for the Caspian Sea lake-level decline in 2000 and 2001. The contribution of submarine mud volcano eruptions to increase Caspian Sea lake level is likely to be negligible on the basis of submarine mud volcanic eruptions in 2003. Both the crustal deformation based on the GPS measurements in the Caspian Sea region and the amount of oil and natural gas production offshore the Caspian Sea are not causing considerable changes in the Caspian Sea lake level.
0388: Hydrologic sciences
0799: Remote sensing