Novel applications of GNSS-R data from TechDemoSat-1 to monitoring the cryosphere

• Main Author: Cartwright, Jessica
• Format: Thesis
• Language: English
• Published: University of Southampton 2021
• Subjects: Antarctic; The Antarctic; Greenland; South Pole; Antarc*; Sea ice; South pole; The Cryosphere
• Online Access: https://eprints.soton.ac.uk/450499/; https://eprints.soton.ac.uk/450499/1/Cartwright_Final_PhD_thesis_July21.pdf; https://eprints.soton.ac.uk/450499/2/Cartwright_Permission_to_deposit_thesis.pdf

As conditions in the cryosphere are expected to change rapidly, it is important to understand the characteristics of these dynamic regions if we are to fully account for their current and future role in the physical systems of the planet. The monitoring of the cryosphere through satellite remote sensing ensures maximum coverage and reliability of measurements otherwise affected by temporal and spatial sampling biases. Here I exploit signals of opportunity in the form of Global Navigation Satellite Systems-Reflectometry (GNSS-R) for this purpose. These signals allow low-cost observation of global systems, using only a receiver and existing navigation satellites in orbit. Data from the SGR-ReSI onboard TechDemoSat-1 (TDS-1) are exploited through the satellite’s initial (November 2014 - July 2017) and extended (August2017 - December 2018) missions. I use the Level 1B data to measure both sea ice and glacial ice in order to assess the potential of these signals for understanding these regions. I produce Digital Elevation Models over the Antarctic and Greenland Ice Sheets. These results demonstrate that when compared with existing products, application of GNSS-R to glacial ice altimetry is possible, acquiring comparable measurements(within 40 cm median difference) to dedicated satellites (eg. CryoSat-2), despite having many fewer measurements, a shorter temporal span and fewer corrections applied. As a multi-static configuration, GNSS-R is in the unique position to be able to obtain measurements at the geographic South Pole itself where traditional altimeters cannot. Use of GNSS-R for the detection of sea ice in both the Northern and Southern Hemispheres demonstrates the potential for future monitoring of sea ice extent using GNSS-R and shows the benefit of the small footprint of such measurements. Seasonal patterns are visible over the extent of the time series, and high agreement is found with four external products. Overall, this thesis finds that GNSS-R holds great potential for use over the cryosphere, with the ...