根据漂流浮标资料对黑潮15m层流路及流轴特征的分析

Analysis of the Path and Axis Features of the Kuroshio at the Depth of 15m Based on Drifting Buoy Data

利用1979-02-2012-03共33 a的水帆位于15m层的Argos漂流浮标资料,绘制黑潮流系15m层的多年年平均和月平均流场,运用特征线方法计算得到黑潮流轴,定义黑潮流动路径的边界为流速大小20～30 cm/s的过渡性区域.结果显示：黑潮多年年平均流路大致是一个以（13°30′N,142°00′E）为圆心、2 235 km为半径的直角弧段,其在吕宋海峡、台湾东北、九州西南及伊豆海岭附近海区发生气旋式弯曲前先进行反气旋式弯曲调整,弯曲处出现的路径开口主要是支流的并入或分支的流出;黑潮流轴整体性偏向黑潮左边界,其中在吕宋岛东北至台湾以东海域最为显著,在本州岛以南海域次之,而在东海段基本居中;黑潮流路上的流速在总体上由南向北呈增大趋势,但并非沿流路持续性逐渐增加,而是呈现出较平直流段的大流速区和弯曲调整流段的低流速区相互交错的状况,其中四国岛以南至伊豆诸岛以西流段的流速为最大.多年月平均流场显示,2月,5月,8月和11月这4个月份是黑潮流路和流轴发生变化的重要转折期,而1月,4月,7月和10月这4个月份则是各季节的代表月份.其中,冬季月份的黑潮流路和流轴最为曲折,向边缘海发生显著入侵;夏季月份的黑潮流路和流轴最为平直,左侧伴随有北向流动;春、秋两季的过渡性特征则比较明显.

Based on the 33-year data of Argos drifting buoy whose sail located at depth of 15 m from February 1979 to March 2012,we plotted annual mean and monthly mean current fields at 15 m depth.The axis of the Kuroshio is derived using the characteristic line method by defining the boundary of the Kuroshio as the transition region where velocity is between 20～30 cm/s.The results showed that：the annual mean path of the Kuroshio is roughly a quarter of a circle whose center is at （13°30′N,142°00′E） and radius is about 2235 km.and it makes anticyclonic adjustment before turning cyclonically at the Luzon Strait,northeast of Taiwan,southwest of Kyushu,and the Izu Ridge coast with inflow merging into or outflow separating off the Kuroshio occurring at the opening where the path bends; the Kuroshio axis overall deviate to the Kuroshio＇s left bouandary,and this feature is most obvious from the northeast of Luzon to the east of Taiwan and is secondary in the south of Honshu Island,while the axis is basically in the middle of Kuroshio＇s boundaries in the East China Sea; the Kuroshio velocity in general to increase from south to north,but the increase is not continuously stable,it shifts alternatively between relatively flat path with higher velocity and curvy path with lower velocity and the maximum velocity appears in the area south of Shikoku Island to west of Izu Islands.Monthly mean current fields showed that the months of 2,5,8 and 11 are important transition periods of the Kuroshio＇s path and axis,and the months of 1,4,7 and 10 are representative moth of the four seasons.The Kuroshio＇s path and axis are curviest during winter months and its intrusion to marginal seas is obvious; While,during summer months,the Kuroshio＇s path and axis are relatively straight with northward flow along left side of the Kuroshio; Spring and autumn are transitional periods.