Accession Number : ADP002728

Title :   Ionospheric Factors Affecting the Performance of HF (High Frequency) Sky-Wave Sea-State Radars,

Corporate Author : RUTHERFORD AND APPLETON LABS CHILTON (ENGLAND)

Personal Author(s) : Bradley,P. A. ; Bramley,E. N. ; Gibson,A. J. ; King,J. W.

Report Date : AUG 1983

Pagination or Media Count : 10

Abstract : This paper contains an assessment, partly theoretical and partly based on observations, of the impact of various ionospheric factors on the usefulness of the HF sky-wave sea-state radar techniques. The points discussed include the following: (a) The ionospheric propagation modes available will not permit all parts of the ocean which it is desired to investigate to be illuminated at all times in such a way that good-quality Doppler spectra are obtained. Es-mode propagation generally results in good-quality Doppler spectra from which information about the sea waves can be inferred, but F-mode propagation yields poor spectra which can only be used to deduce the surface wind direction, (b) Doppler shifts associated with vertical ionospheric motions give spectral contamination which limits the amount of information that can be derived. Spectral contamination also arises under conditions of multi-mode propagation and when high- and low-angle rays are present, and (c) Lack of knowledge of the height of reflection of the sky-wave signals means that the area of ocean probed cannot be located accurately.

Descriptors :   *Doppler radar, *Ionospheric disturbances, *Sea States, *Ocean waves, Wind direction, Doppler effect, Contamination, Low angles, High frequency, Spectra, Observation, Oceans, Multimode, Surfaces, Ionosphere, Propagation, Parts

Distribution Statement : APPROVED FOR PUBLIC RELEASE