ASA 127th Meeting M.I.T. 1994 June 6-10

3aAO9. Acoustic transmission of Taiwan's Northeast Sea.

Chi-Fang Chen

Dept. of Naval Architecture and Ocean Eng., National Taiwan Univ., 73 Chow-Shan Rd., Taipei, Taiwan, ROC

Tai Lee

Chung-Shan Inst. of Sci. and Technol., Taiwan, ROC

The Northeast Sea of Taiwan is characterized by the turning of the Kuroshio current and mixing of water masses from the same current, East China Sea, and Taiwan strait. Its bottom topography consists of the shelf and the shelf slope. Kuroshio export exchange program (KEEP) was conducted by oceanographers from Taiwan to study the complexities of this region. An acoustic study was also included. An acoustic transmission experiment was conducted via fixed receivers and a towed source emitting cw tone of 170 dB re; 1 (mu)Pa, 1 m at 400 Hz along three predetermined tracks in the region. The tracks are of flat bottom and slope bottom. The ambient noise in this region is high; its level reaches 80 dB or higher at 400 Hz. The region is basically a bottom-limited acoustic environment. A PE model was used with an acoustic model constructed by real data of water column and bottom material. The numerical results agree well with the experimental data. The acoustic effect of a cold eddy in the region was studied numerically using a PE model with KEEP oceanography data. A cold eddy of 50 km in diameter along 200-km track was studied. The eddy causes 5 dB more losses in acoustic transmission.