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Abstract

MASS CONCENTRATION (MASCON) parameters are alternative way to represent mass distribution variation. Since 1960s, the MASCON method has been used to represent the mass distribution of the Earth and other planets using information from satellite tracking data. Via this approach, the Earth mass variation is modeled in a specific region and over a specific time period. In fact, mass variations are expressed on regular geometric shapes as a uniform layer (which represents the equivalent water level). In contrast to the spherical harmonic method, the MASCON regional method provides a condition to reduce the observation noise and correlation errors during the process of solving the inverse problem through regularization methods, which are superior to low pass filtering. One of the drawbacks of the MASCON method is the use of spherical harmonic basis functions, which do not have the ability to express local signals. In this research, the MASCON method is used based on local harmonic functions, including the spherical cap harmonic, for mass distribution change modeling. This research focuses on the presentation of TWS variations over Iran using LGD (Line of Sight Gravity Differences) data obtained by GRACE-FO missions based on the MASCON technique in terms of spherical cap harmonic basis functions to provide nearly full extraction of mass variation signal over a spherical cap region that is generally underestimated by GRACE Level 2 product.