Justin Stopa (U. Hawaii, USA); Ralph Foster (Univ. of Washington/APL, USA); Bertrand Chapron (IFREMER, France); Ryan Eastman (Univ. of Washington, USA)

A new joint NASA/CNES imager aboard the Surface Water and Ocean Topography (SWOT) satellite is now providing the widest global ocean coverage of any earth observing radar system yet launched. It's been known since the early SEASAT synthetic aperture radar (SAR) mission that radar imaging of the sea surface can reveal a wide range of air-sea interaction processes with applications that span from search and rescue to ocean wave and weather prediction. This study describes central characteristics of ocean radar backscatter imagery collected using SWOT's primary ocean sampling mode including the scope of oceanic, atmospheric and air-sea interaction phenomena that the radar can resolve. SWOT Ka-band interferometric SAR images differ substantially from previous satellite SAR measurements in four key respects including spatial resolution (500 m), operating frequency (36 GHz), and incidence angle (near-nadir). The final difference is maritime environment spatial coverage, and this is arguably the most important. SWOT imagery is provided continuously along the satellite track over a nearly 120 km swath opening new opportunities to systematically investigate sub-mesoscale air-sea interaction embedded within synoptic weather systems as well as over regions of strong ocean-atmosphere exchange such as western boundary current systems. We illustrate and discuss the benefits and limitations of SWOT using an observational investigation of SWOT versus SAR measurements, this using comparison between coincident SWOT and Sentinel-1 C-band SAR WV mode imagery. It is expected that image interpretation of wind-wave signatures is simplified using these low-incidence angle Ka-band data. We will show that SWOT offers several new capabilities to the earth observing system and provide a first list of potential applications using this new sensor.