Mapping of North Atlantic winds by HF radar sea backscatter interpretation

Abstract

This work presents preliminary results on attempts to map winds of a storm at long range (500 to 1000 nmi) over a large area (105 m i 2 ) in the North Atlantic from the U. S. Naval Research Laboratory, H F radar research facilities at Chesapeake Beach, Md.[l]It appears that the short time response of the sea surface to local winds can be mapped by the analysis of a matrix of rangeazimuth records containing frequency power spectra of HE radar signals backscattered from the sea surface via the ionosphere. This paper presents such a map based upon the ratio of the strengths of the &st-order contributions to the backscatter spectrum (the approach-recede first-order Bragg lines) and is compared qualitatively with a U. S. Weather Bureau map of the area.

A Long-range Ocean Radar for Ocean Surface Studies using Backscatter Via the Ionosphere

“…While it seems likely (Crombie 1971;Barrick 1972b) that ionospheric Doppler shifts will normally be manifested as displacements of the first-order peak from its theoretical position, these must inevitably lead to the broadening of the Bragg peak and to uncertainties in the position and magnitude of the secondary spectral peaks as longer periods of data are included in deriving each spectrum. Attempts by Long and Trizna (1973) and Ahearn et al (1974) to overcome this problem have involved the use only of the two (positive and negative Doppler frequencies) first-order Bragg peaks and the neglect of higher-order details. This approach relies on empirical relationships which are themselves subject to considerable uncertainty, particularly for complex sea surface conditions.…”

Measurement of Sea Scatter and Buoy Tracks at Long Ranges by High- Resolution OTH-B Radar

“…Long and Trizna [1] were first to publish radar maps of ocean wind direction obtainec' at long ranges with skywave propagation [2]. Barrick e_t £l.…”

“…Ahearn ££ al. [4] mapped ocean wind directions with the method in [1], and also attempted to infer ocean wind speeds from the ocean scatter magnitude near zero Doppler. Tyler et al [5] inferred the directional spectrum of sea waves near Wake Island with a bistatic surface-wave radar.…”

Interpretation of Backscattered HF Radio Waves from the Sea

“…Backscatter of HF radio waves has been used for many years as a remote probe of the sea surface (Crombie 1955;Ward 1969;Long and Trizna 1973;Valenzuela 1974;Barrick et aZ. 1974;Barrick 1977;Lipa 1977;Barrick et al 1977;Trizna et oZ.…”

“…The classical mistake is to assume that the surface behaves like a ruled diffraction grating or a crystal lattice, the rulings or lattice planes corresponding to crests in the waves, separated by the wavelength Aw (Crombie 1955;Ward 1969;Crombie 1971;Long and Trizna 1973;Valenzuela 1974;Barrick et al 1974;Barrick 1977;Lipa 1977;Barrick et al 1977;Trizna et al 1977;Teague et al 1977;Lipa and Barrick 1980;Maresca and Carlson 1980;Dexter et al 1982). In that case we have (Lipson and Lipson 1969) …”