Autocovariance Spectrum of Sound-Velocity Microstructure in Deep Caribbean Water

Aiming at a complete representation, two large sets of data taken with horizontally towed velocimeters were analyzed for the range of reciprocal path length, 10−2→2−2 M−1. The first set of data was taken at four latitudes, 13°N→16°N on the longitude 68°W, towing a simply weighted velocimeter at depths between 500 and 1000 m. Using an effective depth and orientation-stabilizng device, a similar set of data was taken at 14°30″N, 62°W for depths between 350 and 1200 m. The sampling interval was 0.25 M and fluctuations were measured from an average calculated over a moving interval of 250 M, then corrected for the depth discrepancy. Total variance ranged between 0.016 and 0.84 M2 sec 2. The spectra are exponential decays that drop into the random level of 0.001 M 2 sec−2 near 1 M−1. Of these total variances a proportion between 0.1 and 0.8 falls without the initial 0.02 M−1. Superposed on the decay are moderate peaks common to all the spectra, some of which can be attributed to short-term undetected depth fluctuation. The spectra of the second set have a smaller proportion of total variance in the initial range. [Hudson Laboratories of Columbia University Informal Documentation No. 85. Work supported by the U. S. Office of Naval Research.]