Kuroshio Variability and its Relationship with Mesoscale Eddies in the southern East China Sea

Abstract

Current velocity of the Kuroshio was observed in the southern East China Sea from June 2015 to June 2017. Based on the 2-year in situ observation data, Kuroshio transport was estimated and its temporal variability is examined associated with mesoscale eddy activity over the region. Stronger Kuroshio accompanied by offshore shift of the current axis is related to anticyclonic eddies on the eastern side of the observation line, whereas weaker Kuroshio accompanied by shelf intrusion and onshore shift of the current axis is associated with cyclonic eddies from the east. Temporally extended time series of the Kuroshio transport by using satellite altimetry data for longer than 20 years exhibits spectral peaks on 60-100 days, which is related to mesoscale eddy variability. It turns out westward propagating eddies from the North Pacific to the Ryukyu Island region modify Kuroshio variability depending on their size, strength, location, etc. Spatio-temporal characteristics of the eddies in the western North Pacific are discussed focusing on their relationship with the Kuroshio variability in the East China Sea.