Sound speed of thermohaline fine structure in the Kuroshio Current inferred from automatic sound speed analysis
Sound speed of thermohaline fine structure in the Kuroshio Current inferred from automatic sound speed analysis
复制标题
DOI：
10.1080/08123985.2020.1736548
复制
发表时间：
2020-03
影响因子：
0.9
通讯作者：
Chanmaly Chhun;T. Tsuji
中科院分区：
文献类型：
--
作者：
Chanmaly Chhun;T. Tsuji
在日本四国岛室户半岛外的黑潮海流中，可以用地震方法绘制海柱内的细尺度温盐结构。在本文中，我们提出了自动声速拾取分析的应用程序，多道地震反射数据采集在不同的时期，以估计时间推移的声速分布在黑潮。该方法基于程函方程和有限差分算法求解的最优速度轨迹。与地震反演技术相比，这种自动分析使我们能够获得对比声速剖面，而不严重依赖于在离散位置直接测量的声速或温度数据。因此，该方法可以可视化的细尺度温盐结构的声速剖面的交叉或diapycnal混合过程中的不同水团在黑潮流。从自动声速分析绘制的所有剖面的图像区分水团及其精细尺度的内部结构，如冷水和温水漩涡，温盐阶梯和内波，揭示了声速和温度变化的界面处的声学对比。将该方法应用于三维地震资料中不同时间步长的单条地震测线，可以为海洋过程以及大尺度海流和气候系统的研究提供精细尺度温盐结构的时空变化图像。
Fine-scale thermohaline structure within ocean column can be mapped seismically in the Kuroshio Current, off the Muroto Peninsula of Shikoku Island, Japan. In this paper, we present the application of automatic sound speed picking analysis to the multi-channel seismic reflection data acquired in a different period to estimate time-lapse sound speed distribution across the Kuroshio Current. This method is based on an optimal velocity trajectory solving by the eikonal equation with a finite-difference algorithm. In contrast to the seismic inversion technique, this automatic analysis enables us to obtain contrast sound speed profiles without heavy dependency on sound speed or temperature data directly measured at discrete locations. As a result, this method can visualise sound speed profiles of fine-scale thermohaline structure developed at interleaving or diapycnal mixing processes of different water masses in the Kuroshio Current. The images of all profiles mapped from automatic sound speed analysis distinguish water masses and their fine-scale internal structure such as cold and warm water eddies, thermohaline staircases and internal waves revealing acoustic contrasts at interfaces across where sound speed and temperature change. Applying our approach for individual seismic line acquired in different time-steps for 3D seismic data can provide time–space variant images of fine-scale thermohaline structure for studies of oceanographic processes as well as large-scale ocean current and climate systems.