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对所收集到的南海北部海区的温度、盐度和深度历史资料进行了声速的计算、统计与分析 ,结果表明该海区上层水体的平均声速场有较明显的年际变化 :表层声速的平面分布显示出沿岸水与外海水强弱交替变化的特征 ,声速等值线的走向几乎与岸线平行 ,等声速线的值自近岸向外海增加 ,大陆架外缘海区声速的水平梯度较大 ;下层声速的分布以环流和水体共同作用的形式出现 ,50m层声速平面分布的趋势除冬季与表层稍为相似外 ,其余季节与表层有明显的差别 ,春、夏季节 50m层声速自西向东增加 ,而秋季与其表层分布相反 ,自近岸向外海减小 ;声速的垂直分布受海水升温与降温的影响显著 ,春、夏季表层海水升温 ,海表声速最大 ,声速自海表随深度的增加而减小 ;秋、冬季表层附近水层降温 ,声速稍偏低 ,普遍出现正梯度现象 ,最大声速移至表层以下的水层 ,这个深度随季节的改变而改变 ,随海区的不同而不同 .该海区的平均声速有年波动现象 ,表层波幅最大 ,随深度的增加波幅变小 ,至 1 0 0m水层其波动的位相几乎与表层相反 .
The velocity, salinity and depth data of the collected data from the northern sea area of the South China Sea have been calculated, analyzed and analyzed. The results show that the average sound velocity field of the upper water body in the sea area has obvious interannual variation: the plane acoustic velocity distribution Showing the alternation of strength between coastal water and outer seawater. The trend of sound velocity is almost parallel to shoreline, the value of iso sonic velocity increases from near shore to outer sea, and the horizontal gradient of sound velocity in the outer edge of continental shelf is larger. The distribution of sound velocity appears in the form of interaction between circulation and water body. The distribution of sound velocity in 50m layer is similar to that in the surface except that the winter is similar to the surface. The sound velocity of 50m layer in spring and summer increases from west to east, In autumn, the surface velocity of sea surface decreases with the increase of sea surface temperature, and the sound velocity of sea surface decreases with the increase of depth ; In autumn and winter, the water layer near the surface cooled down and the sound velocity slightly lower, and the positive gradient generally appeared, and the maximum sound velocity was shifted to the water layer below the surface layer, which The depth varies with the seasons and varies with the sea area.The average sound velocity in the sea area fluctuates year by year with the maximum amplitude of the surface layer and the amplitude decreases with increasing depth, in contrast .