Estimating wind speed from HF skywave radar sea backscatter
Journal Article
·
· IEEE Trans. Antennas Propag.; (United States)
Linear expressions relating ocean surface wind speed to a theoretical estimate of the -10 dB width of the high frequency (HF) sea echo Doppler spectrum (0.078 Hz Doppler shift frequency resolution) are derived for different radar frequencies. The -10 dB width, determined from theoretical model estimates of the Doppler spectrum as a function of radar frequency for a wide range of ocean wave conditions, changes in a complex way with the continuum of second-order echoes surrounding the stronger first-order echo. Because the amplitude of the second-order echoes is directly related to changes in the directional ocean wave spectrum, the wind speed estimates derived from these expressions are highly dependent on the wave field (both the total energy and its distribution with direction); significant differences in these expressions are also found, for example, between fetch-limited and fully developed seas, and for wind seas and swell. These expressions are extremely difficult to use experimentally to obtain reliable estimates of wind speed because a priori knowledge of the wave field is required to apply the correct expression, and yet this knowledge cannot be determined from the unresolved second-order structure at this spectral resolution. Several Doppler spectra recorded under known ocean wind and wave conditions illustrate the difficulty in applying these theoretical expressions to estimate wind speed.
- Research Organization:
- Remote Sensing Lab., SRI International
- OSTI ID:
- 6006210
- Journal Information:
- IEEE Trans. Antennas Propag.; (United States), Journal Name: IEEE Trans. Antennas Propag.; (United States) Vol. AP-30:5; ISSN IETPA
- Country of Publication:
- United States
- Language:
- English
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