浅海温跃层对水声传播损失场的影响

The effects of shallow water thermocline on water acoustic transmission loss field

基于声学调查实测传播损失数据和UMPE(the University of Miami parabolic equation)模型仿真,研究东海近海温跃层对水声场的影响。针对传统声学模型对不同水文要素和海洋过程难以综合考虑的限制,利用同一海域不同航次不同季节声学调查数据,综合海底地形、底质和海面实时气象水文特点,研究水声场声传播损失在浅海温跃层影响下的变化特征。结果表明,水声传播损失场是声源和水听器间几何位置及水体温、盐要素的综合反映,水声场受温跃层季节变换强烈影响。夏季正跃层海洋环境,传播损失随深度增加而较小;春季逆跃层海洋环境,声传播损失随深度增加而增大,无跃层时影响较小。温跃层对高频声场环境影响较小,对低频声场环境影响较大。

Based on the acoustic experimental data on transmission loss and the UMPE （ the University of Miami parabolic equation） model simulation, research into the effects of the offshore thermocline in the East China Sea on the water acoustic field was made. Due to the restrictions of the traditional acoustic model, different hydrological factors and various oceanic processes are hard to be comprehensively considered. Therefore, this paper makes use of observation data from the same sea region, in several navigations and different seasons, and combines seabed, landform, bottom shelf, and the real-time meteorological and hydrological conditions of the sea surface. Research into the change characteristics of the acoustic transmission loss in the water acoustic field under the influence of shallow-water thermocline was also conducted. The results show that, the water acoustic transmission loss field is the comprehensive reflection of the geometric location of the sound source and underwater microphone, water tem-perature and salt factor. The water acoustic field is greatly affected by the seasonal change of the thermocline：sum-mer conditions give rise to a strong positive thermocline, acoustic TL（ transmission loss） decreases following the in-crease of the water depth;while negative thermocline exists in the spring, acoustic TL increases following the in-crease of the water depth, and the acoustic TL changes little when no thermocline exists. The thermocline gives a more forceful impact on the low-frequency acoustic field than the high-frequency acoustic field.