CoAuthors

Christopher Ruf (University of Michigan, Ann Arbor, MI, United States); Cinzia Zuffada (Jet Propulsion Laboratory, Pasadena, CA, United States); Paolo Cipollini (National Oceanography Centre, Southampton, United Kingdom)

The altimetric application of GNSS-Reflectometry (GNSS-R) was proposed for the first time back in 1993 (PARIS concept), and has undergone numerous improvements since then, becoming recently the main focus of the GEROS-ISS experiment, scheduled to be deployed in 2018 on the International Space Station. The current predicted precision for Sea Surface Height (SSH) estimation using GNSS-R still remains on the order of tens of centimeters, but the multistatic nature of GNSS-R makes this technique very attractive in virtue of the high space-time sampling, free transmitters and low-cost receivers. Airborne and tower-based experiments have proven the feasibility of the technique, but a full error budget assessment for SSH from satellite GNSS-R data has so far only been based on simulations. With the launch of TechDemoSat-1 (TDS-1) satellite by Surrey Satellite Technology in July 2014, a fairly large dataset of oceanic GPS-Reflections (GPS-R) has recently become available. The global dataset of GPS-R data is expected to increase dramatically with the launch of the CYGNSS microsatellite constellation in October 2016.
This study presents an analysis of TDS-1 data for SSH estimation. Two test areas are selected, one in South Atlantic and one in North Pacific, and SSH is extracted from delay waveforms, using the simple Leading Edge Derivative (LED) algorithm. Results are compared with the mean SSH over the two areas, from the DTU10 model. A reasonable and encouraging agreement is observed between SSH derived from TDS-1 and the DTU10 model, despite the numerous limitations of the data used, being the GPS-R instrument onboard TDS-1 designed primarily for scatterometric purposes.