Long‐term acoustic tomography measurement of ocean currents at the northern part of the Luzon Strait

[1] An ocean acoustic tomography (OAT) experiment was conducted during May to September 2008 in the Luzon Strait where the Kuroshio sporadically intrudes and strong internal tides and waves occur. Although the reciprocal sound transmissions between two acoustic stations were remarkably disturbed by these waves, ocean current signals proportional to the travel time differences, were successfully retrieved by low-pass filtering out the high frequency wave components under these conditions. The drift of internal clock occurring during the observation is corrected through the procedure that the travel time differences for rays passing the upper 500 m layer are determined relative to those for rays passing near the underwater sound channel (USC) axis of depth about 1000 m. The observed currents relative to currents near the USC axis agree with the moored upward looking ADCP (acoustic Doppler current profiler) data. This study suggests a potential ability of OAT for the operational measurement of ocean currents.