中国东部沿海热含量的多时间尺度变化

Multi-time-scale variation of the heat content in the marginal sea east of China

对中国东部沿海热含量的多时间尺度变化特征进行研究,目的是得出中国东部沿海热含量的多尺度变化规律及相关影响机制。在年际尺度上,将热含量与尼诺3.4指数(Nino 3.4 Index)进行相关分析;在年代际尺度上,将热含量与北太平洋环流振荡指数(NPGO Index)和太平洋年代际振荡指数(PDO Index)分别进行相关分析,发现中国东部沿海200 m水深以浅的陆架海域热含量与NPGO指数在年代际尺度上相关性最高,为正相关,相关系数达到0.40,置信度超过90%。流场与NPGO指数的回归及合成分析结果表明,黑潮区流场与NPGO指数存在负相关。我们将影响机制归纳为:NPGO正异常时,中国东部沿海黑潮流速减慢,由于地转平衡作用,会有大量高温高盐的黑潮水侵入中国东部沿海,将热量传输到黑潮左侧的中国东部沿海陆架区域,引起该区域海水热含量增加。

The characteristics of multi-time-scale variation of heat content in China marginal seas are investigated in order to obtain the variation regulations and the related influence mechanisms.It is found that the thermal content of the continental shelf shallower than 200 m water depth is highly correlated with the North Pacific circulation oscillation index(NPGO Index)by analyzing the correlation between the heat content and the Nino 3.4 index on the interannual time scale,and the correlations between the heat content and the NPGO Index and Pacific Interdecadal oscillatory index(PDO Index)on the decadal time scale.The correlation coefficient on the decadal time scale is 0.40,over 90%confidence level.The regression and composite analysis of flow field and NPGO index show that there is a negative correlation between the Kuroshio Current and the NPGO index.We sum up the influence mechanism as follows:In the positive NPGO years,the Kuroshio velocity slows down.Due to the geostrophic equilibrium,a large amount of high temperature and high salt Kuroshio water will invade the marginal sea east of China and transmit heat to the shelf area to the left of the Kuroshio,resulting an increase of the heat content in this area.