台湾东北部黑潮在流函数空间的水文分析

HYDROGRAPHY OF THE KUROSHIO NORTHEAST OF TAIWAN WITH A STREAMFUNCTION PROJECTION METHOD

利用一种流函数投影方法对台湾东北部黑潮近20年的历史水文数据进行了诊断分析。结果表明,苏澳海脊北部位于冲绳海槽西南角的黑潮中层水的盐度明显高于周围海区;而位于1000m以下的冲绳海槽黑潮深层水相对于苏澳海脊以南的黑潮深层水具有高温低盐的特征,反映了苏澳海脊对黑潮水团的阻挡作用;位于300m以浅的冲绳海槽黑潮热带水相对于苏澳海脊以南的黑潮热带水具有低温低盐的特征。对冲绳海槽西南角黑潮中层水高盐中心的成因分析表明,除苏澳海脊的阻挡作用外,台湾东北部常年存在的气旋式冷涡与黑潮主体在陆架坡折交汇区的垂直混合过程也是需要考虑的物理因素。

A streamfunction projection method called Geostrophic Empirical Mode（GEM） was used to diagnose the historical hydrographic data in the Kuroshio northeast of Taiwan.By examining the spatial and seasonal variations of the GEM fields,we found that the Kuroshio Shallow Water（300 m） in the Okinawa Trough is fresher and colder than that south of the Su-Ao Ridge.It provides evidence that the returning branch of the cyclonic cold eddy north of Taiwan exerts a strong influence on the water properties in the southern Okinawa Trough.Meanwhile,the Kuroshio Deep Water（1000 m） is comparatively fresher and warmer within the Okinawa Trough,reflecting the topographic blocking on the Kuroshio Deep Water mass by the ridge.A regional salinity maximum of the Kuroshio Intermediate Water（KIW） was revealed in southwestern corner of the Okinawa Trough,which is,in hypothesis,the result of the intensive mixing in the confluence region between the Kuroshio and the perennial cold eddy.