Relative-time inversions in the Labrador Sea acoustic tomography experiment.

• Main Authors: Kindler, Detlef, Send, Uwe, Skarsoulis, E. K.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Hirzel 2001
• Subjects: Labrador Sea
• Online Access: https://oceanrep.geomar.de/id/eprint/4071/; https://oceanrep.geomar.de/id/eprint/4071/1/Kindler,%20Acoustic%20Tomography%20Labradorsea,%202001.pdf

One-year long travel-time data from the second deployment period of the Labrador Sea acoustic tomography experiment are analyzed, using a relative-time matched-peak approach, in order to invert for the sound-speed field and simultaneously solve for an unknown travel-time offset. From the relative-time inversions oceanographic information in terms of vertically averaged temperatures are deduced, yielding satisfactory matching with respect to available independent observations. The estimated offsets can be attributed to differential clock drifts, showing a clear parabolic behaviour over the course of the experiment, reaching maximum deviations from linear clock drift corrections (end-point calibrations) of the order of 50 ms. By applying the estimated second-order corrections to the travel-time data, absolute-time matched-peak inversions can then be performed. The used matched-peak approach accounts for the non-linear behaviour of travel times, which is due to the seasonally variable acoustic propagation conditions in the probed region, and turns out to be an appropriate tool in dealing with unknown travel-time offsets.