Orbit-specific tropospheric effects on Sentinel-1A/B interferometric synthetic aperture radar observations: insights for deformation analysis and future mission design

Le résumé fourni par la source

Interferometric Synthetic Aperture Radar (InSAR) is a powerful tool for mapping surface movements, but tropospheric delays complicate deformation interpretation. Tropospheric errors are influenced by various spatiotemporal factors, including water vapor, temperature and pressure and all these factors are related to satellite orbit configurations. This means that although tropospheric errors are independent of signal wavelengths, different satellites may encounter completely different tropospheric effects. However, while previous studies focus on physical properties of the troposphere, orbit-specific tropospheric features remain underexplored. In this paper, we investigate the spatiotemporal characteristics of tropospheric effects using nine years of image pairs globally derived from Sentinel-1A/B’s orbit constellation configuration (acquisition intervals, dates and time of day) and the Generic Atmospheric Correction Online Service for InSAR (GACOS). Our findings quantify pronounced spatial heterogeneity and temporal variability in tropospheric errors, with globally variable linearity, seasonality and randomness in image pair time series. Linear constrained time series inversions (e.g., image pair stacking) demonstrate the effectiveness of long-temporal-baseline image pairs in enhancing accuracy, but such improvement is not continuously growing, highlighting the need to balance the number of image pairs with achievable accuracy. Obtaining seasonal deformation faces greater challenges due to dominant tropospheric seasonality, especially in cases with delayed seasonal responses driven by processes like groundwater extraction or water erosion. These findings offer a framework for understanding tropospheric effects and practical recommendations for improving deformation inversion accuracy, providing valuable insights that can serve as indicators for orbit parameter design and optimization of future SAR missions.

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