Penina Axelrad (University of Colorado Boulder, United States); Stephen Lowe (NASA Jet Propulsion Laboratory, United States); Cinzia Zuffada (NASA Jet Propulsion Laboratory, United States); Dallas Masters (University of Colorado Boulder, United States)

CyGNSS is a constellation of 8 small satellites launched in December 2016 that carries the Surrey Satellite Technologies (SSTL) SGR-ReSI GNSS Reflections (GNSS-R) receiver. Developed as the primary science instrument for CyGNSS, the SGR-ReSI receiver performs real time onboard navigation and generates delay-Doppler correlation maps for Earth reflected GPS L1 C/A ranging signals. While these functions were designed primarily to facilitate the retrieval of ocean surface wind speeds, this research explores ocean surface altimetry retrievals using the CyGNSS data sets. The data sets analyzed here span March 18 – June 3, 2017 at +/- 38 deg latitude.

This early analysis includes consideration of the transmitter and receiver orbits, models for ionospheric and tropospheric delays, mean sea surface topography and ocean tides in the propagation model. A statistical analysis of the 1 second integrated surface height residuals is presented. We focus on comparing retrieved sea surface heights from high SNR measurements in the Indian Ocean to regional topographic models. The leading error residuals are estimated to determine the current level of performance of GNSS-R altimetry with the CyGNSS configuration.