More Phenomenology: Updates to Using the Surface Water and Ocean Topography (SWOT) Ka-band Satellite for Novel Inland Retrievals of Hydrological Parameters

The Synthetic Aperture Radar (SAR) frequency on the Surface Water and Ocean Topography (SWOT) Mission is Ka-band with an 8mm wavelength. In contrast, lower frequencies, such as those from NISAR and Sentinel-1, are the preferred method for most land surface studies because they have all-weather capabilities, and they can penetrate vegetation to reveal sub-canopy ground deformations, and they make water detection easy as water surfaces are uniform. Lower frequencies make these types of vegetation and surface water observations easier, while higher frequencies make these observations harder. Because of this, as a high-frequency system, SWOT was never designed to penetrate canopies or examine ground deformations. Rather, the high frequency from SWOT was selected for its potential to produce very high-resolution observations and have strong sensitivities to surface water, with the primary goals of measuring water surface elevations and water surface extents. Despite this, recent studies being published have demonstrated SWOT sensitivities related to 1) wind-driven water surface roughness, 2) vegetation structure, and 3) sub-canopy ponding and soil moisture. This presentation highlights progress in examining SWOT observations for Even More Than Surface Water Topography in support of improving SWOT discharge algorithms and other critical water cycle algorithms, such as for evaporation, transpiration, and canopy interception, for further-reaching improvements to water resources research.