海面高度計と海洋観測データを用いた北海道南沖合域の海況変動 １９９２年１０月〜１１月の事例解析

Abstract

Sea surface heights (SSHs) derived from TOPEX/POSEIDON (T/P, hereafter) altimeter are used together with in situ data and AVHRR IR images to investigate the ocean south of the Hokkaido Island. We processed the T/P data to derive SSH anomalies from 1-year averaged SSHs along the T/P satellite subtracks, and the SSH maps produced from the SSH anomalies and the 20-years averaged hydrographic SSH. Comparing each observation results, the oceanic conditions during October to November, 1992 are described. A mooring system with current meters was located just under a T/P subtrack. The cross-track surface current anomalies derived from T/P altimetry and observed at 138m depth by the mooring system are compared favorably with a correlation coefficient of 0.55 and a root mean square error of 7.6 cm/s. The Kuroshio Extension, the warm-core rings, and the Oyashio current are confirmed by the AVHRR images and the cross-track surface current anomalies along the T/P subtracks. On the contrary, the narrow band of the Oyashio current does not appear in the SSH maps though the Kuroshio Extension and the warm-core rings are confirmed. It is demonstrated that combination of the SSH derived from the altimeter, the AVHRR IR images and the hydrographic observation data may be a useful tool to investigate the complicated oceanic conditions formed by the Oyashio, the Kuroshio Extension and the warm-core rings in the ocean south of the Hokkaido Island.