一个西太平洋冷涡影响下的会聚区声传播变异特征分析  

Abnormal features of the convergence zone caused by the cold eddy in Western Pacific

作　　者：张旭[1,2] 程琛[1] 邱仁贵[3] 

机构地区：[1]中国人民解放军91550部队,辽宁大连116023 [2]92493部队博士后科研工作站,辽宁大连116023 [3]中国人民解放军92488部队,广东湛江524064

出　　处：《海洋通报》2015年第2期130-137,共8页Marine Science Bulletin

摘　　要：以Argo资料给出的一个典型西太平洋冬季冷涡为环境背景,应用BELLHOP高斯束射线模型计算声场,通过比较环境水平不变与环境水平变化声场的差异性,得出了涡旋环境和地形变化共同影响下会聚区声场出现的一些变异特征。分析结果表明,涡西侧声场在深海平坦地形条件下会聚区保持完整,从涡外向涡内传播时会聚区距离逐渐变小,反之距离变大,同时,涡中心附近的冷水上涌破坏了近表层的表面声道,使声传播损失突然增大。涡东侧的海山地形阻碍了会聚区反转,使声场出现了复杂的变异特征,如会聚区的截断、上反转点的抬升或下降、声线的多途传播以及增益位置的不规则变化等。这些声场变异特征是由西太平洋的背景环境、涡中的水文非均匀分布以及地形变化共同引起的。当地形变化不影响会聚区反转时,声场变化主要受涡锋面两侧水文环境差异的影响,典型特征是会聚区的偏移和表面声道的生消;当地形变化对会聚区反转产生明显的干扰时,地形条件对于声场能量分布具有主导作用,非均匀水文环境的影响弱化,但仍起到重要的调制作用。Based on a typical cold eddy environment in the Western Pacific in winter provided by Argo data, we employ BELLHOP Gaussian beam model to calculate acoustic field, and describe some abnormal features of convergence zone（CZ）in an eddy and unconstant topography enviroment by comparison between range-independent and range-dependent cases.Our results indicate that CZ can be integrally maintained under conditions of smooth abyssal terrain in the western side of the eddy. The CZ becomes shorter in range when sound is propagating from eddy interior to exterior, and becomes longer contrarily. Moreover, the surface duct is destroyed by an upwelling of cold water around eddy centre, inducing an increased transmission loss near the surface field. By comparison, the CZ can be obstructed by a seamount terrain, and produce some complicated phenomena, such as the truncation effects, the raising and falling of turning point near the surface, the multiple paths of beams and the irregular distribution of gain position, and so on. These findings suggest that the abnormal phenomena of acoustic field should be attributed to the climatological environment of the Western Pacific, the asymmetry of hydrological distribution caused by eddies, and the topography change. The acoustic field is mainly affected by the eddy fronts environment when CZ is independent of topography, which shows a CZ deviation and surface duct fading. Contrarily, the topography plays a leading role when CZ is obviously obstructed, but the hydrological environment still has a modulated function.

关 键 词：中尺度涡 西太平洋 会聚区 ARGO 高斯束射线模型 

分 类 号：P733.21[天文地球—物理海洋学]