黑潮入侵对南海东北部初级生产力的影响

Influence of Kuroshio intrusion on primary productivity in the northeastern South China Sea

黑潮流经菲律宾东岸时部分水体经吕宋海峡入侵南海东北部。冬季黑潮入侵会明显提高南海东北部的初级生产力,阐明黑潮入侵对初级生产力的影响将为分析渔业生产力和渔场渔汛提供重要基础。该研究利用1997年-2014年的卫星遥感数据进行分析,结果表明冬季黑潮入侵明显提升南海北部外海的初级生产力,其影响范围可达南海北部外海面积的一半;1997年以来,南海东北部初级生产力均呈现冬季高而夏季低的特点,并未出现异常年份;1997年和1998年受强厄尔尼诺影响,南海东北部初级生产力明显低于常年,除此之外,1999年以来该海域冬季和全年的初级生产力呈显著下降趋势。该研究还根据初级生产力和表层海流的分布和变化情况,判断各年冬季黑潮入侵的主要路径类型。1997年以来的17个冬季,黑潮流套、黑潮南海分支和黑潮跨越吕宋海峡等3种路径均曾出现,以南海分支路径为主,但统计检验表明冬季黑潮以不同路径入侵,南海东北部的初级生产力并没有显著差异。

A fraction of the Kuroshio flowing east off the Philippine coast intrudes into the northeastern South China Sea（ NESCS）through the Luzon Strait. The intrusion which takes place in winter can improve primary productivity in the oligotrophic NESCS greatly.Thus,study of the effect of Kuroshio intrusion on primary productivity will provide important references for predicting fish productivity and fishing operations. The data from satellite observation from 1997 to 2014 show that winter intrusion of the Kuroshio has enhanced primary productivity in the open waters remarkably and the area influenced could cover as large as one half of the oligotrophic northern SCS. Since 1997,without exception,the primary productivity in the NESCS has exhibited the lowest values in summer but the highest ones in winter. Impacted by a strong El Nio event,the primary productivity was exceptionally low in 1997 and 1998,and since 1999 the winter and annual primary productivities in the NESCS have shown a significant decreasing trend. Based on the spatial and temporal patterns of primary productivity and sea surface current,the analysis also determines the major types of Kuroshio intrusion path for every winter. The results show that for the 17 winters since 1997,the looping path,leaking path and leaping path of Kuroshio intrusions have all occurred and the winter intrusion mostly taken the path of a SCS branch. However,statistical tests show no significant differ-ence of primary productivity in the NESCS between the Kuroshio intruding paths in winter.