Tomographic Maps of the Ocean Mesoscale. Part 1. Pure Acoustics,
CALIFORNIA UNIV SAN DIEGO LA JOLLA INST OF GEOPHYSICS AND PLANETARY PHYSICS
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A field test of ocean acoustic tomography was conducted for 2 months in 1981 in a 300 km square at 26 deg N, 70 deg W in the North Atlantic. From measured travel times between moorings, various displays of the three- dimensional field of sound speed closely related to temperature were obtained by inversion procedures. These procedures use historical ocean data as a reference, but all information from the in situ surveys has been withheld the pure tomographic results were then compared to direct in situ observations. The tomographically derived spatial mean profile compares favorably to an equivalent profile from the in situ observations both differ significantly from the historical average. Maps constructed at three day intervals for a two month period show a pattern of eddy structure in agreement with the direct observations within computed mapping errors, but these mapping errors are too large for many oceanographic purposes. The mapping errors are the result of an unexpectedly large noise variance in travel time. The 1981 tomographic results strongly suggest that the ocean sometimes undergoes transitions too rapid to be mapped over such large areas by shipboard observations.
- Physical and Dynamic Oceanography