Studies of TDS-1 GNSS-R ocean altimetry using a “full DDM” retrieval approach

The use of GNSS-R (Global Navigation Satellite System Reflectometry) for Earth remote sensing is becoming an increasingly attractive approach thanks to its inexpensive and passive method. While GNSS-R ocean altimetry has been studied extensively, previous studies have focused on the use of the delay waveform (DW) only in the retrieval of sea surface height. This paper presents sea surface height retrievals using a “full Delay-Doppler Map (DDM)” method, and applies the approach to measurements of TechDemoSat-1 (TDS-1), a recent space-borne mission. The End-to-End Simulator (E2ES) of GNSS-R waveforms developed for the CYGNSS mission is adapted for use with TDS-1 and applied as the forward model used in the retrieval process. Comparisons between measured and modeled DDMs have been conducted as a first step to validate this process. Retrievals of sea surface height using both the DW and full-DDM methods will be reported in the presentation. Potential methods for improving estimation error for future GNSS-R missions will also be described in the presentation.