由小斜率近似计算空气声经粗糙海面透射至深海中的声场

采用一级小斜率近似方法处理空气声经粗糙海面透射至深海中的声场问题,导出了透射场及其相干分量的表达式。假定海面高度一维变化且频谱满足PM谱,采用小斜率近似方法计算了相应的透射场。对于空气中的线源,小斜率近似与积分方程方法结果一致。当水下测量点距离较远且深度较浅时,平均声强随海面均方根高度增加而增加至一极限值,相干声强则随海面均方根高度增加而一致减小。对于空气中的点源,小斜率近似计算表明,水下平均声强还依赖于测量点相对于声源的方位,而相干声强则与测量点的方位无关。 

Sound transmission from air into deep ocean through rough sea surfaces by small slope approximation

The first-order small slope approximation is applied to the problem of the sound transmission from an airborne source into deep ocean through a rough sea surface, and expressions are derived for the transmitted sound field and its coherent component. Numerical calculations are performed. The sea surface is assumed to be random rough with a Pierson-Moskowitz spectrum and have height variations in only one dimension. For the case of the airborne line source, the small slope approximation results are in good agreement with those from integral equations, and show that the mean of sound intensity at observation direction with shallow depression angle increases and approaches a limit as the root-mean-square surface height increases, while the coherent field intensity consistently decreases. For the case of the point source, the small slope approximation results show that the mean of sound intensity depends significantly on the source-receiver bearing angle, but the coherent field intensity is independent of this angle.