SWOT Water Surface Elevation in Herbaceous Wetlands of Florida's Everglades

Abstract Observing water level variations in wetlands is important for tracking global water and carbon cycles. The Surface Water and Ocean Topography (SWOT) mission was launched to measure Earth's surface waters, but its performance in vegetated wetlands was unknown. Here, we present the first assessment of SWOT over herbaceous wetlands in Florida's Everglades. Comparison of SWOT water surface elevation (WSE) measurements against in situ water levels from 5 August 2023 to 30 March 2024, shows strong positive correlation ( r > 0.99) and mean absolute error of 6.7 cm for WSEs averaged over 1 km 2 regions. Water surface elevation errors within 10–60 km of the SWOT observation swath have similar precision and accuracy. SWOT's performance in large herbaceous wetlands is better than pre‐launch expectations for large open water bodies, which is unexpected. Our results suggest we can accurately track water level variations in many of Earth's large herbaceous wetlands globally. Additional evaluation is needed in shrubby and forested wetlands.