Fine-scale thermohaline structure within ocean column can be mapped seismically in the Kuroshio Current, off the Muroto peninsula of Shikoku Island. In this paper we present the application of automatic seismic velocity picking analysis to the MCS (Multi-Channel Seismic) reflection data acquired in different period to estimate sound speed and temperature distribution as a variation of time 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 seismic inversion technique, this automatic analysis enables us to obtain contrast velocity profiles without heavily dependency on velocity or temperature data at discrete locations. As a result, this method can visualize velocity and temperature profiles of fine-scale thermohaline structure developed at interleaving or mixing processes of different water masses in the Kuroshio Current. The images of all profiles distinguish water masses and their fine-scale internal structure mapped from sound speed contrasts at interfaces across where velocity and temperature change. Our results also imply that this seismic reflection technique (application to individual seismic line acquired in different time-steps for 3D seismic data analysis) can provide time variant images of fine-scale thermohaline structure for studies of oceanographic processes as well as large-scale ocean current and climate systems.
|Title of host publication
|Proceedings of the The 13th SEGJ International Symposium
|Published - Apr 29 2019