بررسي روند سيزده ساله تغييرات سطح آب درياي خزر از راه ارتفاع سنجي ماهواره اي

Assessment of 13 years of sea level variations at the Caspian Sea using satellite altimetry observations.

The goal of this research is the study of sea level variations of the Caspian Sea. For this purpose the satellite altimetry data of Topex/Posidon (T/P) and Jason-1, and coastal tide gauge observations at Anzali, Sdra, and Noshahr harbors are used. The algorithmic steps of the research are as follows: (1) As the first step the data from T/P and Jason-1 satellites are collected and standard corrections are applied to the data. (2) The Caspian Sea is divided into cells and Sea level changes are studied within those cells. (3) The coastal tide gauge observations are analysed for periodic and non-periodic changes. (4) The same analysis as of step (3) is applied to the Satellite Altimetry data for recognition of periodic and non-periodic changes of the Caspian Sea level. For steps (3) and (4) Fourier transform and Least Squares Spectrum analyses were performed. An almost steady slope from Southwest towards Northeast is observed in terms of orthometric heights of the mean Caspian Sea level. (5) Dynamic height of mean Caspian Sea level is computed and it was found that the observed slope is mostly of non gravimetric origin. The potential information needed for the computation of the dynamic height of the mean Caspian Sea level was provided by EGM96 geopotential model after being transformed into ellipsoidal harmonic coefficients and applied in ellipsoidal harmonic expansion of the Earthʹs gravitational field. Finally, the methodology applied in this research is offered to users via a software, which allows the sea level variation study of the Caspian Sea via satellite altimetry observations.