Wind direction estimated from SeaSonde HF radar during Typhoon Songda

The wind directions obtained from three land-based SeaSonde HF radar systems, operated at 4.58 MHz, are compared with ground-truth winds during the passage of Typhoon Songda in 2011. The wind direction retrieval at each radar range cell about 10.2 km wide is based on cardioid energy distribution of Bragg wind waves. The ground-truth winds from either data buoy or meteorological stations suggest that the SeaSonde wind direction is most reliable at the range cell most close to the shore. For range cell farther away from shore, the SeaSonde wind direction becomes less reliable. The SeaSonde winds remain further justifications for the validity of the wind retrieval algorithm from SeaSonde.