Phase-resolved ocean wave forecast with simultaneous current estimation through data assimilation

In Wang & Pan (J. Fluid Mech., vol. 918, A19, 2021), the authors developed first ensemble-based data assimilation (DA) capability for reconstruction and forecast of ocean surface waves, namely EnKF-HOS method coupling an ensemble Kalman filter (EnKF) high-order spectral (HOS) method. this work, we continue to enrich by allowing it simultaneously estimate current field, which is in general not known a priori can (slowly) vary both space time. To achieve goal, incorporate effect (as unknown parameters) on waves build HOS-C as forward prediction model, obtain simultaneous estimation (current) parameters (wave) states via iterative EnKF (IEnKF) that necessary handle complexity DA problem. The new algorithm, named IEnKF-HOS-C method, tested synthetic problems with various forms (steady/unsteady, uniform/non-uniform) current. It shown able only field accurately, but also boost accuracy wave (even) relative state-of-the-art Finally, using real from shipborne radar, show successfully recovers speed matches situ measurement floating buoy.