Temporal And Spatial Variability Of Heat Transport Of The Kuroshio In The East China Sea

The Kuroshio heat transport has the significant impact on the climate change and marine ecological environment in the coastal areas of China.Based on JCOPE2 high resolution numerical simulation data from 1993 to 2016,firstly,the temporal and spatial variations of Kuroshio heat transports(KHT)in the East of Taiwan and the impact factors were analyzed.Then the onshore Kuroshio heat transport across 200 m isobath over the continental shelf of the East China Sea and its temporal and spatial variations were examined using daily reanalysis data,and the correlation and time lag between the Kuroshio heat transport in the bottom layer of northeast of Taiwan and the temperature at the bottom over the continental shelf of the East of China sea were analyzed.Finally,the influence of Kuroshio in the east of Taiwan on the intrusion of Kuroshio to the shelf was discussed.The finding and conclusions are as follows.The KHT acrossing the KET(Kuroshio East of Taiwan)section has a significant seasonal variation,its magnitude is larger in spring and summer,but smaller in autumn and winter.The annual mean value of KHT is 1.98PW and its standard deviation is 0.18PW.The KHT stronger years were 1996-1997 and 2015;weaker years were 2000,2002 and 2013.By using the variance analysis,the maximum value of the velocity variance term accounts for 77%of the total variance of the KHT.The covariance term of temperature and velocity and variance term of temperature account for 15%and 6%of the total variance of KHT,respectively.Super ENSO has significant effect on the interannual variations of KHT.During super El Nino events,the KHT increased distinctly and its peak value appeared about 5-10 months ahead of the peak of ONI index.Most of the Kuroshio heat loss occurred in East China Sea,the magnitude is about 102.22X 1012W,the Kuroshio heat lossin the Yellow Sea is 0.71 × 1012W.The net heat flux into the atmosphere from the Kuroshio of East China Sea is 263W/m2,about 40%of the net heat flux into the East China Sea.The annual mean value of net KHT across the whole 200m isobath is 74.81 × 1012 W,and there is a significant seasonal variation,the KHT is much lager in autumn and winter and smaller in spring and summer.There are three main intrusion locations over 200m isobaths,the most significant intrusion occurs in the northeast of Taiwan with KHT of 213.83×1012W,accounting for about 50%of the onshore KHT across the whole 200m isobaths.The temperature across the northeast of Taiwan suggests a three-layer structure,the temperature in the surface layer is higher than 21? and the bottom layer is below 18?.The annual mean KHT in the bottom layer of northeast of Taiwan is 5.47×1013W,and there is a significant seasonal variation with high value in spring and summer and low value in autumn and winter.The nearshore Kuroshio branch in bottom reached 27.5°N costs 60 days and 90 days to the Yangtze estuary coast.Correlation analysis suggests that when Kuroshio volume transport east of Taiwan increases(decreases)in winter(summer),the intrusion across the 200m isobath decreases(increases).On interannual time scales,there is a negative correlation between Kuroshio east of Taiwan and the intrusion across the 200m isobaths,when Kuroshio volume transport east of Taiwan decreases,it is favorable for the intrusion across the 200m isobath.