A Closed-Form Analytical Solution for HFSWR Wind Direction Inversion Using the von Mises Model

Wind direction inversion in high-frequency surface wave radar (HFSWR) relies heavily on the directional distribution model (DDM). The classical Longuet-Higgins (L-H) model causes non-physical spatial discontinuities due to energy truncation in the upwind direction. While the Donelan model corrects this defect and achieves higher accuracy, its inversion still relies on non-linear optimization or numerical discretization, resulting in low computational efficiency. The Apel model, though simple in