2002年春季吕宋海峡海流:观测与改进逆模式计算
Currents in the Luzon Strait during spring of 2002: observation and computation by modified inverse model
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摘要: 基于2002年春季航次在吕宋海峡海域锚碇测流站(20°49'57"N,120°48'12"E)200,500与800m处锚碇测流以及CTD观测,采用改进逆方法对调查海域进行海流计算.(1)主要观测的结果:1)在200m处,观测期间海流平均速度为(47.4cm/s,346°).在500m处,海流观测期间平均速度为(20.3cm/s,350°).这些都表明黑潮在吕宋海峡锚碇测流站200和500m处向西北方向入侵南海.2)在800m处,海流观测期间平均速度为(1.2cm/s,35°),它的方向为东北向.比较每层实测流结果,表明800m层海流状况与200和500m层流况不同.3)在观测期间,200,500和800m处,日平均流速在4月皆比3月时要强.4)在调查海区西部的中间区域存在一个高密、冷水中心(HDCW),其中心位置位于断面A的水文站3附近.5)在调查海区东南区域存在一个低密、暖水(LDWW)中心,其中心位置位于断面B的水文站8附近.(2)主要计算结果:1)通过断面B的偏北方向与偏南方向的流量分别为32.48×106m3/s(包括反气旋涡的流量)与3.34×106m3/s.因此通过断面B的净北向流量为29.14×106m3/s.2)通过断面A的东向与西向的流量分别为16.71×106m3/s与8.57×106m3/s(包括气旋涡的流量).因此,通过断面A的净东向流量为8.14×106m3/s.3)通过断面M北向的净流量为24.68×106m3/s.4)黑潮通过断面M后分为主流和一个支流,其主流,流量为16.54×106m3/s,流向断面C的东部分.主流通过断面C的东部分后,最后流向台湾以东海域.而其一个分支,净流量为8.14×106m3/s,在一个高密、冷水中心(HDCW)的区域以东作气旋式弯曲,然后向西北方向通过断面C的西部.因此,黑潮在断面C有两个流核.5)比较计算得到的在锚碇测流站M附近流方向与在200与500m处观测流方向为西北向,它们甚为一致.6)在断面B西侧位于550m以深水层南海水可能缓慢地从西北流向东南,通过断面B的南向流量大约为3.34×106m3/s.
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关键词:
- 2002年春季吕宋海峡海流 /
- 海流观测 /
- 改进逆方法
Abstract: On the basis of the current measurements at 200,500 and 800 m from moored currentmeters with the time series data from March 17 to April 15 at the mooring station (20°49'57"N,120°48'12"E) and the hydrog raphic data obtained on the both sides of Luzon Strait (LS) in spring of 2002 cruise,the circulation in the investigated area is computed by using the modified inverse method.The major observed results are as follows: (1) the average velocity in the observing days is (47.4 cm/s,346°) at the 200 m levels.The average velocity in the observing days is (20.3 cm/s,350°) at the 500 m levels.These mean that the Kuroshio intrudes in the South China Sea(SCS) to flow northwestward through the Luzon Strait at the 200 and 500 m levels.(2) The average velocity in the observing days is (1.2 cm/s,35°) at the 800 m levels,i.e.,its direction is northeastward.This means that the flow condition at the 800 m levels very differs from that at the 200 and 500 m levels.(3) There is the high density and cold water (HDCW) in the middle of western part of in the investigated region,and its center is located near the hydrological station 3 at Section A.(4) There is the lower density and warm water (LDWW) in the southeastern part of investigated region.The major computed results are as follows: (1) The northwestward and southeastward volume transports (VT) through Section B are 32.48×106 (inclusive of VT of anti-cyclonic eddy) and 3.34×106m3/s,respectively.The net northwestward VT through Section B in the investigated area is about 29.14×106m3/s.(2) The eastern and western VT through Section A is about 16.71 and 8.57×106m3/s,respectively.Thus,the neteastward VT through Section A is about 8.14×106m3/s.(3) The net northward VT through Section M is about 24.68×106m3/s.(4) After about 24.68×106m3/s flows through Section M,most of it,about 16.54×106m3/s,flows northward through the eastern part of Section C and then flows northward into the region east Taiwan Island.A part of it,about 8.14×106m3/s,branch out from the main Kuroshio and then flows meanderingly through the western part of Section C.Thus,the Kuroshio has the two cores of current at Section C.(5) The direction of the computed current near the mooring station Magrees with the direction of the current measurements at 200 and 500 m from moored current meters.(6) About 3.34×106m3/s of the SCS water probably flows slowly from the northwest to the southeast in the layer below 550 m at the western part of Section B. -
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