Exploitation of novel SWOT data for polar ocean applications (ESPOLA)

• Applicants: Dr.-Ing. Denise Dettmering; Dr.-Ing. Felix Müller
• Subject Area: Geodesy, Photogrammetry, Remote Sensing, Geoinformatics, Cartography
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 563438082

In December 2022, the novel satellite mission SWOT (Surface Water Ocean Topography) was successfully launched, which is not only able to observe water levels in the nadir, but also provides information on the ocean topography in a 150 km wide swath around the satellite ground track for the first time by using radar interferometry. SWOT has a significantly higher spatial coverage and resolution compared to conventional satellite altimeters and therefore offers a completely new type of dataset. The main focus of the mission is on the open, ice-free ocean and continental hydrology, but parts of the ice-covered polar oceans are also covered. ESPOLA provides a detailed analysis of SWOT's innovative data in polar regions and investigates their scientific utility for sea-ice regions. For this purpose, observations of conventional altimetry missions and in-situ data, for example from tide gauges, are used. In particular, ESPOLA aims to develop methods for processing SWOT data and to investigate how the data can be used to generate improved high quality geophysical datasets (sea surface heights, sea ice concentration and geostrophic currents). Furthermore, the advantages of radar-interferometrically observed water surfaces and a comparison to conventional nadir altimetry in terms of accuracy and resolution is worked out and quantified. Special attention is given to the effects of polar winds and their signatures on SWOT observations in water openings in the ice and at the ice edge. Moreover, combination strategies between conventional nadir data and SWOT observations are evaluated. First interferometric data from SWOT in the polar regions show promising potential to observe the dynamically changing conditions in the polar oceans and thereby contribute to a better understanding of ocean heights and currents in the ice-covered ocean. ESPOLA shall address this and develop fundamental knowledge about the evaluation and application of SWOT interferometry data in the polar oceans. With the help of the methods developed in the project, the first geophysical datasets are created and evaluated.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr.-Ing. Florian Seitz