夏季加拿大海盆海冰边缘区声体积后向散射强度研究

Study on volume backscattering strength in summer marginal ice zone of Canada Basin

声信号的体积后向散射强度是声传播过程中一个关键的参数。海冰边缘区的声体积后向散射强度研究对深入认识北极声场环境有着十分重要的意义。本文利用中国第六次北极科学考察获取的数据资料研究了海冰边缘区声体积后向散射强度特性。结果表明:加拿大海盆海冰边缘区是声体积后向散射强度的明显过渡区。无冰海面(海冰密集度小于15%)海洋深层水的声体积后向散射强度明显大于密集海冰区域的海水(海冰密集度大于50%)。讨论了声体积后向散射强度与海冰融化之间的关系,造成融冰区声体积后向散射强度增大的原因是水下悬浮泥沙、浮游生物等悬浮物质增加。根据海冰密集海域的海水后向散射强度弱的特点,对北极下放式声学多普勒测流仪(LADCP)观测的设置提出建议。

Volume backscatter strength （Sv） is a key parameter for acoustic transmission. Study on volume back- scattering strength in marginal ice zone （MIZ） in the Arctic plays an important role in the knowledge of the Arctic acoustic environment. Based on the investigation during the Sixth Chinese National Arctic Research Expedition in summer 2014,the characteristics of backscatter strength in MIZ are analyzed. The results show that Sv under the open water （ice concentration less than 15%） is significantly higher than that in seawater under the packed ice （ice concentration more than 50%）. Ice melt causes increasing of opaque creatures and suspended sediment,and leads to increase of Sv. According to the characteristics of low Sv under the packed ice,the proposal about the parameters of LADCP setting is given.