Advancing CYGNSS Derived Ocean Surface Heat Fluxes

Global Navigation Satellite System Reflectometry (GNSS-R) leverages GPS signals scattered from the ocean surface, offering potential utility across all weather conditions. This overview highlights recent advancements in NASA's Cyclone Global Navigation Satellite System (CYGNSS) level-2 ocean surface turbulent heat flux products. We adjusted the air-sea bulk formula to calculate turbulent heat fluxes using stability-independent CYGNSS satellite winds, addressing stability-dependent biases between equivalent neutral winds and actual winds. Despite remaining errors due to uncertainties in model-derived air-sea parameters and satellite wind data, this adjustment improved the accuracy of CYGNSS-derived sensible and latent heat flux estimates in comparison to buoy-based bulk fluxes, yielding a bias reduction of 10-20 W m-2 for latent heat flux and 1-2 W m-2 for sensible heat flux. Spatial analysis further indicated that the adjusted fluxes generally exhibited lower magnitudes than the unadjusted ones, with significant variations in regions prone to highly unstable atmospheric conditions, such as the Arabian Sea, the Bay of Bengal, the Kuroshio Current / Extension, and the Western Boundary Currents during winter, and near the equator in July. These developments represent a significant step in refining CYGNSS-derived surface heat flux products, offering more reliable data for studying air-sea interactions and advancing weather and climate research.