SWOT Phenomenology for Lakes and Wet-Lands

This research seeks to determine the sensitivity of the recently launched Surface Water and Ocean Topography (SWOT) mission’s SAR scattering over lakes and wet-land surfaces to identify the utility and feasibility of SWOT to produce novel data sets outside of the scope of the original SWOT mission. In particular, two core tracks are investigated: (1) wind speeds over large and moderate-sized lakes, greater than 1km², and (2) moisture variability on the ground and within vegetation.SWOT is the first high-resolution Ka-band SAR mapping satellite, producing observations of high-frequency scattering at near nadir look angles. While wind speeds are commonly retrieved using multi-azimuth scatterometers, the spatial resolution of these satellite scatterometers are 1000 times more coarse compared with SWOT, limiting their utility in inland waters. In contrast, the higher spatial resolution from SWOT suggests possible retrievals of wind speed and wind direction, although the accuracy of the wind direction estimate is not expected to match the accuracy of scatterometers. In addition to being sensitive to wind variability, historical airborne observations with similar geometric configurations suggested that SWOT observations might also be sensitive to surficial soil moisture and vegetation texture.Upon examination of the 1-Day Fast Sampling Orbit beta-prevalidated data, we show the sensitivity of SWOT backscatter to wind speeds and directions over open water and to surface moisture and vegetation structure. Ongoing work aims to identify the feasibility of using SWOT HR PIXC backscatter observations to retrieve novel data sets.