Sunwoo Yoon (Department of Earth Sciences, Southern Methodist University, Dallas, TX, USA, United States); Christopher Arp (Water and Environmental Research Center, University of Alaska Fairbanks, Fairbanks, AK, USA, United States); Allen Bondurant (Water and Environmental Research Center, University of Alaska Fairbanks, Fairbanks, AK, USA, United States); Tamlin Pavelsky (Department of Earth, Marine and Environmental Sciences, University of North Carolina at Chapel Hill, NC, USA, United States)

Over terrestrial environments, the Surface Water and Ocean Topography Mission (SWOT) is designed to retrieve elevation over lakes and rivers globally. It is estimated that globally, the majority of satellite resolvable lakes and rivers experiences seasonal ice cover, which limits SWOT hydrology application over a large portion of its target water bodies during the winter. Some preliminary studies have demonstrated SWOT's ability to detect the presence of ice/snow and estimate ice surface elevation over both inland water ice cover and sea ice. To date, most evaluation studies have compared SWOT-retrieved elevation over ice with elevation from altimeters. In this work, we aim to conduct a field-based study to evaluate ice elevation from SWOT. To capture the complexity of the lake/river ice environment, we conducted a four-day field study near Fairbanks, Alaska. We collected dense GNSS data over morphologically complex ice cover using Trimble R12i with its RTX service. The data were collected at 1 second interval by towing a GNSS receiver behind a snow machine over an accumulated distance of ≥120 miles, covering two segments of the Tanana River, Healy Lake, and Harding Lake. The RTX service provides data with ~5 cm vertical accuracy to be compared with SWOT's reported elevation. The data will be converted to SWOT's reference frame before comparing with SWOT's pixel cloud and raster product. We expect the results will be useful in further demonstrating SWOT's applicability in cryosphere studies. And given the complexity of the river/lake environment, the resulting evaluation will likely provide a lower bounds for SWOT's ice elevation retrieval accuracy over various snow/ice conditions in terrestrial environments.