Anisotropic Behavior of Atmospheric Disturbances in Coastal Areas for Satellite Radar Interferometry: Significance and Mitigation Strategy

Abstract. Tropospheric phase delays pose significant challenges for accurate deformation measurement using Interferometric Synthetic Aperture Radar (InSAR), especially in coastal regions characterized by complex atmospheric dynamics. Conventional correction methods typically assume isotropy, overlooking directional variations in atmospheric turbulence. In this study, we systematically investigate the anisotropic behavior of tropospheric delays across diverse geodynamic regions of Iran, including coastal areas (Makran Coast, southern Zagros, central Alborz) and inland regions (South Khorasan), using empirical variogram analyses on more than 1,200 interferograms. Our results confirm pronounced anisotropy in coastal zones, attributable to complex topography and variable moisture distributions. Among tested variogram models (exponential, Gaussian, spherical), the exponential model consistently provided the best fit, reducing variogram modeling error (RMSE) by up to 56.8% compared to alternative approaches. Further evaluation using Least Squares Collocation (LSC) under varying observational scenarios revealed that anisotropic modeling substantially improves tropospheric corrections, notably achieving a 50% accuracy enhancement (up to 15 cm) in sparse or uneven sampling conditions typical of coastal environments. However, under dense, uniform sampling, anisotropic modeling showed minimal advantage. These findings underscore the critical importance of considering anisotropic atmospheric turbulence to enhance the precision and reliability of InSAR-derived geophysical measurements, particularly in challenging coastal settings.