Wind direction is a parameter that has been measured with HF radars over many years. It is obtained by taking the ratio of the amplitude two first order Bragg peaks (the same signal that is used for current measurement except there we use the frequency of the peaks) and applying a directional wave model. It is the short wave direction that is actually being estimated but, in most circumstances, these waves are expected to be aligned with the wind and hence the direction can be interpreted as wind direction. For the WERA data this measurement can be made with the Seaview package [1,2, 3] which is not yet implemented. In the meantime the amplitude of the two peaks is included in the single radar NETCDF files and the ratio of these can be used to provide qualitative information about the changing wind directions.

Accurate wind speed estimation is still a research area for HF radar. The Seaview package when implemented will provide an estimate but it is not expected to be very accurate particularly in low wind/swell cases.

References

[1] Wyatt L.R., L.J. Ledgard, C.W.  Anderson, 1997: Maximum likelihood estimation of the directional distribution of 0.53Hz ocean waves. Journal of Atmospheric and Oceanic Technology, 14, 591-603.

[2] Wyatt L.R., 2012: Short wave direction and spreading measured with HF radar. To appear in Journal of Atmospheric and Oceanic Technology.

[3] Heron M.L., 1987: Directional spreading of short wavelength fetch-limited wind waves. Journal of Physical Oceanography, 17,281-285.

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