Acoustic variabilities in the central part of the East Sea: Low-frequency acoustic propagation in presence of the Sub-polar front

Acoustic environmental changes and their effects on underwater sound propagation in the central part of the East Sea are investigated by analyzing available observation data acquired since 1993. The characteristics of underwater acoustic propagation in this area are closely related with various oceanic physical processes such as the Sub-polar front (SPF), eddies, warm and cold currents. Especially, the SPF has been considered as a acoustic barrier against sound propagation across the front. To investigate low frequency underwater acoustic propagations in the SPF of the East Sea, numerical experiments are conducted with Range dependent Acoustic Model (RAM). Significant seasonal variations of sea water properties are existed across the SPF region from the north and the south. The model results show that transmission loss decrease (about 20dB) with ideal front in the warm region whereas transmission loss increase (about 25dB) with ideal front in the cold region.