[A-CG37] 衛星による地球環境観測

[ACG37-P14] Kuroshio meander northeastern Taiwan observed from multi-satellite data and drifters

*Po-Chun Hsu^1,2、Dorathy Yuan-Jane Lo³ (1.Center for Space and Remote Sensing Research, National Central University, Taiwan、2.Institute of Hydrological and Oceanic Sciences, National Central University, Taiwan、3.School of Natural and Environmental Sciences, Newcastle University, United Kingdom)

キーワード：Kuroshio, Mesoscale eddy, Coastal current, Taiwan, Chlorophyll concentration, Sea surface temperature

The interaction between the Kuroshio current (KC) and mesoscale eddies is an important marine phenomenon in eastern Taiwan. The characteristics of the ocean current in northern Taiwan are complex, including tidal current, wind-induced, eddies, and topographic effects. At present, we have known that the ocean current in northern Taiwan is mainly composed of the northeastern Taiwan countercurrent (NETCC), the northern Taiwan coastal current (NTCC), and the KC. However, we still do not know much about the long-term variations and the interaction of the three currents. Therefore, this study used multi-satellite data and drifters to analyze the Kuroshio meander and its path changes in northeastern Taiwan in the past 30 years and its impact on the offshore waters of Taiwan. The long-term average position of the KC path at 25^oN is 122.75^oE, and there is NETCC between the western boundary of the KC and Taiwan. The variability of the KC at 25^oN is usually have branches flowing westward into northern Taiwan and branches deflecting northward and eastward into the East China Sea. The westward branch has a long-term average of 0.16 m/s, which is significant from October to February, with up to 78% of the days appearing, while only 17% in summer (June to August). However, this branch changes greatly in each different year, and it is most likely to be affected by the mesoscale eddy. The eddy identification is divided into three areas (A: 24-26^oN, 120-121^oE; B: 25-26^oN, 121-123^oE, and C: 25-26^oN, 123-124^oE). In zone A, almost all of them are cyclonic eddies, with an average of 3.6 times a year, which will affect the ocean current flowing from the Taiwan Strait into northern Taiwan. The average occurrence of cyclonic eddy in Zone B is 4.1 times a year, and that of the anticyclonic eddy is only 0.7 times, but its life cycle is long. Zone C is mainly controlled by anticyclonic eddy, which occurs twice a year on average. These eddies cause the KC path to change and produce a variety of branch paths. In addition, this study also observed the interaction between the KC and the eddy using the hourly drifter data, and the response of the sea surface temperature and chlorophyll concentration along the coast of Taiwan after the Kuroshio meander, especially under the effect of cyclonic eddy.