Acoustic tomography experiment in the eastern Arabian Sea

An acoustic transmission experiment was conducted in the eastern Arabian Se a along 12.5 degrees N latitude for a duration of ten days (2-12 May, 1993) , with two transceiver systems depolyed on deep sea moorings, separated by a range of 270.92 km. Hourly reciprocal transmissions were carried with a t ime lag of 30 minutes between each direction. From the multipath arrival pa tterns, significant peaks corresponding to the predicted ray arrivals were identified and travel time perturbations of the most stable eigen rays enab led reconstruction of temperature anomaly from the sound speed perturbation . A linear relation was used to transform sound speed perturbations in the vertical plane to temperature perturbations, for the first four days of tra nsmission, following Munk and Wunsch [1]. The 2 - D temperature anomaly der ived from the six hourly mean travel-time data showed a gradual warming of the top layers, signatures of diurnal variability and intrusion of Red Sea waters.