Advances in EOS-04 SAR data processing: polarimetry, repeat-pass interferometry and analysis-ready data products

EOS-04 (Earth Observation Satellite-04), launched on 14 February 2022, is a follow-on mission to Indian Space Research Organisation’s first synthetic aperture radar (SAR) satellite RISAT-1. It is capable of imaging in either side of the track with incidence angle range from 12.2° to 55.1°. Onboard SAR system supports variety of resolution and swath requirements and can operate in various modes like StripMap, ScanSAR and Sliding Spotlight modes with various polarization combinations like linear, hybrid and full/quad polari­metry. EOS-04 is the first spaceborne SAR mission worldwide supporting full-polarimetry (FP) data acquisitions in ScanSAR modes. Availability of FP datasets in wide swath modes (ScanSAR modes) is a big step towards scientific analysis for various applications in a time-bound manner. For enabling interferometric processing, EOS-04 orbits are being maintained within the baseline requirements of 500 m. EOS-04 has 17 days repetivity resulting in less temporal decorrelation to use the datasets for various deformation studies. In addition to this, analysis ready data (ARD) product, normalized radar backscatter (NRB) Gamma0 product, are introduced to minimize the user efforts for any immediate analysis. In NRB Gamma0 products, terrain induced variations particularly on hill-slopes affecting the brightness of the radar return is normalized by applying radiometric terrain correction (RTC) on SAR images. This paper discusses about the data processing aspects related to calibration, polarimetry, interferometry and NRB Gamma0 product generation