Passive Microwave Ocean Surface Vector Wind Measurement Uncertainty Assessment

A new Ocean Surface Vector Wind (OSVW) retrieval algorithm has been developed, leveraging Northrop Grumman’s EVEREST end-to-end environmental sensing system models and simulation tools, to support the Weather Satellite Follow-on Microwave system development. Based on a mature geophysical inversion technique and state-of-the-art ocean surface emissivity models, this generic retrieval algorithm can be implemented to produce the OSVW data products from passive polarimetric microwave radiometer measurements such as WindSat and MicroWave Imager (MWI). Some unique features of the new algorithm include explicit retrieval of atmospheric transmittance, downwelling and upwelling radiances, analytical computation of Kernel functions derived from the radiative transfer equation, and synergistic use of NWP model forecast wind direction to constrain wind direction retrieval and to reduce ambiguity. The algorithm’s performance has been extensively tested using both WindSat proxy data and high fidelity EVEREST simulated test data. In this paper we will present the performance verification test results and the end-to-end error budget analysis that highlights the capability and limitation of passive microwave technology for measuring ocean surface wind vector.