111-3 Evaluating Tropospheric Delay Modeling for Enhanced Geospatial Accuracy

Session: Using Near Surface Geophysics to Investigate Geological Problems (Posters)

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Abstract:

Interferometric Synthetic Aperture Radar (InSAR) is a vital technique for monitoring ground surface deformation across large spatial scales. However, variability in atmospheric water vapor, pressure, and temperature introduces tropospheric delays that can significantly affect measurement accuracy. These delays are often corrected using outputs from numerical weather prediction (NWP) models. RAiDER, an open-source Python package, facilitates this by estimating tropospheric delays using models such as the High-Resolution Rapid Refresh (HRRR). Previous studies have shown that weather model–based corrections can substantially reduce atmospheric noise in InSAR data but also highlight persistent residual errors, especially at spatial scales smaller than the model grid resolution. This study aims to quantify the magnitude of residual tropospheric delay that persists after HRRR-based correction, using GNSS-derived Zenith Total Delay (ZTD) as ground truth. Specifically, we assess the accuracy of NWP-derived delays at spatial scales smaller than a single model grid cell. The analysis is conducted across three GNSS-dense regions in the United States: Rolla, Missouri (June 2024–March 2025); Salt Lake City, Utah (January–February 2020), and Mineral, California (January–October 2020). Standard deviations of the ZTD residuals are 3.53 cm in Rolla, 2.08 cm in Salt Lake City, and 2.72 cm in Mineral, highlighting spatial variability in model performance due to local atmospheric conditions. These residuals are used to develop a statistical model that estimates the uncertainty in InSAR-derived velocities and displacement time series resulting from unresolved sub-grid-scale atmospheric noise. The framework established in this work supports the development of more robust tropospheric correction strategies, thereby enhancing the reliability of InSAR for geodetic and hazard-monitoring applications.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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