Three-Dimensional Distribution of Sound Speed in the Iceland-Faeroe Area, Retrieved from a CTD Survey, Thermistor-Chain Measurements and Satellite SST Imagery
Abstract
The three-dimensional variability of sound speed in the Iceland-Faeroe Frontal (IFF) region is investigated. Emphasis is put on the question, to what extend subsurface sound speed may be determined from space-borne remote sensing. Data from different sources are used: CTD survey and thermistor-chain measurements as ground truth and satellite infrared imagery. Most of the data are temperatures which, for the area under consideration, quite accurately determine the sound speed. From the subsurface data it is shown that the vertical sound-speed profiles can be decomposed into empirical orthogonal eigenfunctions (EOFs), with the first two already accounting for 97% of the variance. High correlation of the first- and second-order EOF amplitudes is found with sea-surface dynamic height, and for the first-order EOF amplitude with sea-surface temperature (SST). The latter relation is used successfully to determine subsurface sound speeds from satellite-measured SSTs. Due to the resolution of the satellite data, horizontal scales are overestimated, and due to the availability of only the first-order EOF amplitude for the construction of sound-speed profiles, a too high vertical correlation is introduced. To overcome these problems, for the purpose of acoustic modelling, a theoretical three-dimensional sound-speed model is developed, based on the EOF decomposition. The EOF amplitudes contain the analytically described front and random portions represented by a finite moving average process.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1994
- Accession Number
- ADB197442
Entities
People
- H. H. Essen
- J. Sellschop
Organizations
- SACLANT ASW Research Centre