台湾岛以东黑潮热输运的季节及年际变化特征

黑潮热输运对我国沿海区域气候变化及海洋生态环境具有重要影响。基于JCOPE2(Japan Coastal OceanPredictabilityExperiment2)模式1993—2016年的高分辨率数值模拟结果,计算了通过台湾岛以东24°N KET(Kuroshio East of Taiwan Island)断面的黑潮热输运,分析了其季节及年际变化特征,结合ONI指数(Oceanic Nino Index)探讨了其与ENSO(厄尔尼诺-南方涛动)事件的关系。研究结果表明, KET断面黑潮热输运具有显著的季节变化,春夏季较大,秋冬季偏小;年均值为1.98 PW(1 PW=10~(15) W),标准差为0.18 PW,热输运强年为1996—1997年和2015年,热输运弱年为2000年, 2002年和2013年。超强ENSO过程对黑潮热输运有显著影响。受超强厄尔尼诺事件影响,台湾岛以东黑潮热输运明显增加,热输运极大值超前ONI指数极大值约5～10个月。利用方差分析得到流速方差项对KET断面黑潮热输运总时域方差贡献最大,解释了热输运总方差最大值的77%,其次是温度与流速协方差项以及温度方差项,分别解释了热输运总方差的15%和6%。

Seasonal and interannual variations of Kuroshio heat transport east of Taiwan Island

The Kuroshio heat transport (KHT) plays an important role in the continental shelf circulation and the associated ecosystems in the East China Seas(ECS). On the basis of the daily reanalysis data from 1993 to 2016 obtained by a data assimilative ocean model developed by the Japan Coastal Ocean Predictability Experiment 2, the KHT east of Taiwan Island was calculated and its temporal and spatial variations were analyzed. Results show significant seasonal variations, in which the KHT is large in spring and summer but small in autumn and winter. The annual mean KHT is 1.98 PW and the standard deviation is 0.18 PW. The KHT is strong in 1996-1997 and 2015 but weak in 2000, 2002, and 2013. The super ENSO has a significant effect on the KHT. During super El Niño events, the KHT increased distinctly and its peak value was detected approximately 5-10 months ahead of the peak of ONI. Variance analysis indicates that the maximum variance of velocity accounts for 77% of the total variance of the KHT. The covariance of temperature and velocity and the variance of temperature account for 15% and 6% of the total variance of the KHT, respectively.