Observed Sound-Speed Variability in the Gulf of Cadiz.
SACLANT ASW RESEARCH CENTRE LA SPEZIA (ITALY)
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Sound-speed fluctuations have been examined by repeatedly profiling temperature, conductivity, and depth over long tow paths. The sound-speed variability due to internal waves conveniently separates from that due to inhomogeneities, revealing that even in an area of complex structure, internal waves are the leading cause of sound-speed fluctuations. At very low wavenumbers .0001 cyclem, variability due to inhomogeneities nearly equalled that due to waves only, whereas at higher wavenumbers they contributed only about one fifth as much variability as waves. The Munk and Zachariasen model estimate of wave-induced fluctuations agrees very well with these data, and allows the further computation of local coherence lengths. A directional dependence of variability is found near the coast. Fluctuations were less by a factor of five looking along the coast than looking normal to it. It may be a general result that, in shoaling areas, sound-speed fluctuations measured parallel to the shore are less than those measured at right angles to the shore. Author