Variabilities of the sea level anomalies in the upstream areas of the Kuroshio Current

Y J Wijaya,S Sugitani,D P Wijayanti,Y Hisaki,D N Sugianto

doi:10.1088/1755-1315/162/1/012045

Abstract

The relationship between The Kuroshio velocities and Sea Level Anomalies (SLA) in the upstream areas (between Taiwan and Yonaguni Island) is investigated based on satellite altimetry observation. Mean of the SLA data from 2005-2008 show that in the northeast of Taiwan tends to form strong eddy activity. Furthermore, the type of eddy that forms in the upstream areas is difference every season, cold (warm) eddy more exists in summer (winter). The speed of the Kuroshio in the upstream areas is determined by combination of High-Frequency (HF) radar and Copernicus Marine Environment Monitoring Service (CMEMS) data. These two are exhibited that Kuroshio speed become faster (slower) in summer (winter). High positive correlation of the Kuroshio speed and SLA are found in between Yonaguni and Iriomote Island. When the Kuroshio speed in the middle of HF radar areas (123.375° N) became faster, it coincided with transition of warm eddy to cold eddy in the northeast of Taiwan and vice versa.

Highlights

Kuroshio called Japan Current, is the strong surface current of the North Pacific Ocean gyre, flowing past Taiwan and Ryukyu Island in Japan
Variabilities of the Kuroshio by HF Radar and Satellite Altimetry In order to facilitate within monitoring of variabilities of the Kuroshio, we need to determine specific point or line that passed by the Kuroshio consistently
Based on HF radar and altimetry data, meridional line at 123.375°E assumed as specific line for the Kuroshio observation

Summary

Introduction

Kuroshio called Japan Current, is the strong surface current of the North Pacific Ocean gyre, flowing past Taiwan and Ryukyu Island in Japan. In the East of Taiwan, Sea Surface Height Anomaly (SSHA) observed by satellite altimetry are found to be well correlated with the Kuroshio transport, both offshore and onshore Kuroshio meandering could be generated by the negative anomaly which are simultaneously with the low Kuroshio transport based on the World Ocean Circulation Experiment (WOCE) PCM-1 [1]. Prior study recognized mesoscale eddy southeast of Taiwan later on would encourage seaward (or coastward) of the Kuroshio east of Taiwan 40 days later [2]. Westward propagating warm eddies from 18°N to 23°N may form a large Kuroshio meander and the meanders led to a large 100-days transport fluctuation in the East Taiwan Channel [3]. El Niño/Southern Oscillation (ENSO) and Pacific decadal oscillation (PDO) have an influence on these variabilities of the Kuroshio [4,5]

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Results

Conclusion