基于海洋模式数据的吕宋海峡输运量和菲律宾黑潮流量关系的分析

ANALYSIS ON THE RELATIONSHIP BETWEEN LUZON STRAIT TRANSPORT AND PHILIPPINE KUROSHIO TRANSPORT BASED ON OCEAN MODEL DATA

利用全球涡分辨率海洋环流模式OFES的60年(1950—2009)输出资料,用流速资料计算了吕宋岛东侧18°N断面黑潮上游流量(Kuroshio Transport,KT)和120.5°E断面吕宋海峡输运量(Luzon Strait Transport,LST)。研究表明,KT和LST存在四种情况,即:(1)KT大LST小、(2)KT大LST大、(3)KT小LST小和(4)KT小LST大,分别占其总数的34%、11%、13%、42%。合成分析证实:一般情况下,KT大对应黑潮跨越吕宋海峡流态,此时LST较小;KT小时,地转β效应迫使黑潮向西入侵吕宋海峡,此时LST大。然而,吕宋岛东侧和台湾东南沿岸的涡旋常削弱黑潮在吕宋海峡处流量,造成KT大时黑潮亦入侵吕宋海峡,从而出现KT大LST大的情形;太平洋一侧的异常高海表高度诱发吕宋海峡处强地转流,造成KT虽小而黑潮在吕宋海峡处仍是跨越流态,因而LST小。结果表明,LST不仅受KT影响,亦受局地涡旋和海表高度的重要控制。

Based on 60-year（1950—2009） monthly mean output from a high eddy-resolving numerical model OFES（OGCM for Earth Simulator）, the variability of the Kuroshio Transport（KT） at 18°N section and the Luzon Strait Transport（LST） at 120.5°E section are investigated. Results indicate that there are four typical cases（strong KT and weak LST, strong KT and strong LST, weak KT and weak LST, and weak KT and strong LST）. The probability of occurrence is 34%, 11%, 13%, and 42% respectively. The composite analysis shows that strong（weak） KT associated with weak（strong） LST occurs frequently during the simulated period. When the KT is strong, the majority of Kuroshio Current traverses off the Luzon Strait and moves northward due to an inertial effect, resulting in weak LST. When the KT is weak, a branch of Kuroshio intrudes through the Luzon Strait and into the SCS due to the β effect, leading to strong LST. However, the Kuroshio can be reduced by anti-cyclonic eddies located at the east of the Luzon Island and off southwest Taiwan, resulting in Kuroshio intrusion and occurrence of strong KT and strong LST. When KT is strong, sea surface height anomaly（SSHA） of the Pacific would be positive, which leads to a strong geostrophic current in the Luzon Strait, and the Kuroshio tends to leap across the LS, resulting in the occurrence of weak KT and weak LST. Therefore, we believe that LST is not only under the influence of KT, but also those of local eddies and sea surface height.