Successful Applications of Generic Atmospheric Correction Online Service for InSAR (GACOS) to the Reduction of Atmospheric Effects on InSAR Observations

Abstract

The tremendous development of Synthetic Aperture Radar (SAR) missions in recent years facilitates the study of smaller amplitude ground deformation over greater spatial scales using longer time series. However, this poses greater challenges for correcting atmospheric effects due to the wider coverage of SAR imagery than ever. Previous attempts have used observations from Global Positioning System (GPS) and Numerical Weather Models (NWMs) to separate atmospheric delays, but they are limited by ①The availability (and distribution) of GPS stations; ②The low spatial resolution of NWM; And ③The difficulties in quantifying their performance. To overcome these limitations, we have developed the Generic Atmospheric Correction Online Service for InSAR (GACOS) which utilizes the high-resolution European Centre for Medium-Range Weather Forecasts (ECMWF) products using an Iterative Tropospheric Decomposition (ITD) model. This enables the reduction of the coupling effects of the troposphere turbulence and stratification and hence achieves equivalent performances over flat and mountainous terrains. GACOS comprises a range of notable features: ①Global coverage; ②All-weather, all-time usability; ③Available with a maximum of two-day latency; And ④Indicators available to assess the model’s performance and feasibility. In this paper, we demonstrate some successful applications of the GACOS online service to a variety of geophysical studies.

Keywords

• |insar|atmospheric correction|gacos|earthquake|volcano|landslide|city subsidence