摘要:
基于日本“长风丸”调查船在2000年5个航次水文资料及同时期QuikSCAT风场资料,采用改进逆方法计算了东海黑潮的流速与流量等,获得了这5个航次期间的主要结果:(1)在东海海区风速1~2月比其他月份时大,风海流也最强.只在7月表层风海流为北向,加强了黑潮流速.(2)表层最低盐度值夏季时最小,1~2月时最大.这再次表明,夏季时长江冲淡水向东北方向扩散,冬季时基本上向南,其他季节在上述两者之间.(3)PN断面流速结构及其变化:黑潮流核在1~2,10和11月时有两个,在4和7月皆只有1个.黑潮主流核在1月位于计算点9,在4,7,10与11月都位于计算点8,即向陆架方向移动.(4)黑潮在TK断面出现多流核结构特性.11月主流核出现在TK断面中部,存在于水深大于1 200 m区域,其余月份主流核皆出现在TK断面北部,存在于深度400m以浅水层.(5)通过PN断面的净东北向流量在11月最大,为28.1×106m3/s,7月时其次,10月时最小,为24.6×106m3/s.通过PN断面的净东北向流量年平均值为26.4×106m3/s.(6)1~2,4,7与10月在PN断面以东都出现暖的、反气旋式涡,10月份时,反气旋式涡最强.只在11月时出现弱的、气旋式涡.黑潮以东反气旋涡加强时,黑潮流量似乎减小(例如10月);相反,当黑潮以东反气旋涡减弱(例如7月)或者代之出现气旋涡时(例如11月),黑潮流量似乎增大.10和11月在PN断面附近流态的比较,揭示了环流变化较大,这进一步表明,黑潮和其附近中尺度涡的相互作用是重要的.(7)通过TK断面的净东向流量,11月最大,7月其次,10与1~2月最小.通过TK断面净东向流量年平均值为21.9×106m3/s.(8)通过A断面的北向流量在1~2与4月较大,分别为3.5×106与3.1×106m3/s,7月最小.通过A断面的年平均北向流量约为2.7×106m3/s,这表明,在2000年1~2与4月通过对马暖流的流量最大,7月时最小.
Abstract:
On the basis of hydrographic data obtained in 5 cruises of 2000 onboad the R/V Chofu Maru and the QuikSCAT wind data during 5 cruises of 2000,the velo city and volume transport (VT) of the Kuroshio in the East China Sea (ECS) are computed by using the modified inverse method.The following main results have been obtained.(1) The wind speeds and wind-driver currents both are strongest in January February among 5 cruises of 2000,and the directions of wind-driver current are northward only in July of 2000,which streng then the Kuroshio current in the ECS.(2) The lowest value of salinity at the surface is minimalin summer,and the lowest value of salinity at the surface is maximal in January-February.This means that the Changjiang River discharge diffuses northeastw ard at the surface layer in summer,but it diffuses southward at the surface layer in winter.(3) The current structure and its variations at Section PN in 5 cruises of 2000 are as follows.The Kuroshio at Section PN has two current cores in January February,October and November,and only one current core in April and July,respectively.The main axis of Kuroshio is located at the computational point 9 of Section PN in January February,and at the computational point 8 of Section PN,which moves toward the shelf,in other months,respectively.(4) The Kuroshio through Section T K has multi-current cores during 5 cruises of 2000.The main current core of Kuro-shio occurs only at the computational point 8,whose water depth is greater than 1 200 m,in November,and occurs at the computational point 2 or 4,whose water depth is less than the 400 m levels,in other months,respectively.(5) The net northeastward volume transport through Section PN is maximal,28.1×106 m3/s,in November among 5 cruises of 2000,and is next in July,and is minimal,24.6×106 m3/s,in October among 5 cruises of 2000.The annual average of its net northeast ward VT is 26.4×106 m3/s in 2000.(6) The week cyclonic eddy occurs only in November and in area east of the Kuroshio at Section PN.But an anticy clonic and warm eddy occurs in area east of the Kuroshio at Section PN in other months,especially,is strongest in October.When an anticyclonic and warm eddy east of the Kuroshio strengthens,the VT of Kuroshio seems to decrease,such as in October.Inversely,when an anticy clonic and warm eddy east of the Kuroshioi is week,such as in July,or when the cyclonic eddy occurs east of the Kuroshioi,the VT of Kuroshio seems to increase,such as in November.In comparison of the current patterns of the circulation in October and November in the ECS,their variations of the circulation are greater in the ECS.This shows also that the interaction between the Kuroshioi and meso-scale eddies near the Kuroshio is important.(7) The net eastward VT through Section TK is maximal also in November among 5 cruises of 2000,and is next in July,and is minimal in October and January February among 5 cruises of 2000.Its annual average net eastward VT through Section TK is 21.9×106 m3/s in 2000.(8) The net northward VT through Section A is maximal,3.5 and 3.1×106 m3/s,in January-February and April,respectively,and is minimalin July among 5 cruises of 2000.Its annual aver age net northward VT through Section A is 2.7×106 m3/s in 2000.This means that the VT of the Tsushima Current is maximal in January February and April,and is minimal in July among 5 cruises of 2000.
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