Circulation Around Luzon Strait in September as Inferred from CTD,Argos and Argo Measurements and a Generalized Topography-Following Ocean Model

The hydrography, wind, Argos and Argo measurements in the areas surrounding Luzon Strait were collected. Based on the hydrographic data obtained during September 1994, the improved Princeton Ocean Model using a generalized topography-following coordinate system together with a modified inverse method was applied to study the circulation in September. Observations and the diagnostic simulation produce a consistent circulation pattern, and the main dynamical features can be summarized as follows. (1) The Kuroshio has two branches with the main Kuroshio existing above 800 m depth and the western part existing above 400 m depth. The western branch of the Kuroshio leaves the main current near 20.5°N, then flows northwestward through Luzon Strait and finally flows out of the northern boundary southwest of Taiwan, consistent with the trajectory of Argos drifters. (2) The non-linear term is important and cannot be neglected in the momentum equations in the northern part of Luzon Strait under the baroclinicity field. Using non-linear dynamics, the westward intrusion of the Kuroshio into the northern part of Luzon Strait is more curved than when using linear dynamics. However, the non-linear term is smaller and so negligible around Luzon Strait under the homogeneous density field. (3) In the area from 117°E to 119°E and from 20.2°N to 21.7°N, an anticyclonic eddy appears east of Dongsha Islands. (4) At depths above 400 m, the circulation is mainly dominated by the basin-scale cyclonic gyre. (5) In the computational domain west of 121°E, the circulation below 800 m is mainly dominated by the basin-scale anticyclonic gyre. (6) The South China Sea water flows eastward across Luzon Strait in the middle layers, then turns cyclonically, finally flowing northward into the region east of Taiwan Island, which is qualitatively in agreement with the trajectories of Argo floats at about 1000 m depth in the area east of 121°E.

RÉSUMÉ?[Traduit par la rédaction] Nous avons rassemblé l'hydrographie, le vent, les Argo et les mesures Argo dans les régions avoisinant le détroit de Luçon. Sur la base des données hydrographiques relevées durant le mois de septembre 1994, nous avons appliqué le modèle océanique amélioré de Princeton utilisant un système de coordonnées « suivant le terrain » généralisé de pair avec une méthode inverse modifiée pour étudier la circulation en septembre. Les observations et la simulation diagnostique produisent une configuration de circulation cohérente dont on peut résumer comme suit les principales caractéristiques dynamiques. (1) Le Kuroshio possède deux branches : le Kuroshio principal existant au-dessus d'une profondeur de 800 m et la partie ouest existant au-dessus d'une profondeur de 400 m. La branche ouest du Kuroshio quitte le courant principal aux environs de 20,5°N et se dirige vers le nord-ouest à travers le détroit de Luçon pour finalement franchir la limite nord du détroit au sud-ouest de Taïwan, ce qui correspond à la trajectoire des bouées dérivantes Argos. (2) Le terme non linéaire dans les équations est important et ne peut pas être considéré négligeable de quantité de mouvement dans la partie nord du détroit de Luçon dans le champ de baroclinité. Lorsqu'on utilise la dynamique non linéaire, l'intrusion vers l'ouest du Kuroshio dans la partie nord du détroit de Luçon est plus incurvée que lorsqu'on utilise la dynamique linéaire. Cependant, le terme non linéaire est plus petit et donc négligeable autour du détroit de Luçon dans le champ de densité homogène. (3) Dans la région allant de 117°E à 119°E et de 20,2°N à 21,7°N, un remous anticyclonique apparaît à l'est des îles Dongsha. (4) Aux profondeurs inférieures à 400 m, la circulation est principalement dominée par le gyre cyclonique à l’échelle du bassin. (5) Dans le domaine de calcul à l'ouest de 121°E, la circulation sous 800 m est principalement dominée par le gyre anticyclonique à l’échelle du bassin. (6) Les eaux de la mer de Chine méridionale s’écoulent vers l'est à travers le détroit de Luçon dans les couches intermédiaires, puis tournent de façon cyclonique pour finalement s’écouler vers le nord dans la région à l'est de l’île Taïwan, ce qui, qualitativement, s'accorde avec la trajectoire des flotteurs Argo à environ 1000 m de profondeur dans la région à l'est de 121°E.     

Argos漂流浮标的若干观测结果

表层漂流浮标是一种利用Argos卫星系统定位与传送数据的海洋观测设备,它可以利用Lagrangian法则连续观测表层海流及表层水温。文章利用近年在南海和西太平洋投放的部分卫星跟踪表层漂流浮标所取得的观测资料,分析观测海域的表层海流特征及其漂移路径上的温度变化,得出以下结果。(1)由浮标的漂移轨迹看出,黑潮表层流路年际变异相当大。(2)2003年1月,黑潮表层水有入侵南海的趋势,似无西北太平洋表层水深入南海的迹象;夏季南海表层水由南海流出经吕宋海峡汇入黑潮主干。(3)秋季台湾东北海区存在一个强反气旋涡,空间尺度约270km。(4)黑潮主干在秋末冬初经过东海时明显呈弯曲流动,并形成许多小尺度的气旋式涡。(5)在九州西南海域,黑潮表层流并无分支北上进入对马暖流区。(6)2003年春季,黑潮在日本以南的弯曲不明显,并伴随有冷、暖涡产生,暖涡的强度和空间尺度都要比冷涡大得多。(7)由漂流浮标观测得到的的表层海水的温度分布明显呈日变化和季节变化的特征。在浮标漂移路径呈反气旋或气旋式转动的区域,表层水温对应出现高或低温区;但出现在台湾以东的低温区则与此时期的台风过境有关。     

Variability of surface velocity in the Kuroshio Current and adjacent waters derived from Argos drifter buoys and satellite altimeter data

By combining Argos drifter buoys and TOPEX/POSEIDON altimeter data, the time series of sea-surface velocity fields in the Kuroshio Current (KC) and adjacent regions are established. And the variability of the KC from the Luzon Strait to the Tokara Strait is studied based on the velocity fields. The results show that the dominant variability period varies in different segments of the KC: The primary period near the Luzon Strait and to the east of Taiwan Island is the intra-seasonal time scale; the KC on the continental shelf of the ECS is the steadiest segment without obvious periodicity, while the Tokara Strait shows the period of seasonal variability. The diverse periods are caused by the Rossby waves propagating from the interior ocean, with adjustments in topography of island chain and local wind stress. Supported by the National Basic Research Program of China (973 Program, Nos. 2007CB411804, 2005CB422303), the NSFC (No. 40706006), the Key Project of International Science and Technology Cooperation Program of China (No. 2006DFB21250) and the “111 Project” (B07036), the Program for New Century Excellent Talents in University (NECT-07-0781)     

Argos表面漂流浮标在黑潮区的若干观测结果

利用近几年国家海洋局第二海洋研究所及国家海洋技术中心在南海和西北太平洋海域布放的部分卫星跟踪表面漂流浮标所取得的观测资料,分析了浮标流经海域的表层海流特征及浮标漂移路径上水温的变化。结果表明:2003年1月,黑潮表层水有入侵南海的趋势,夏季南海表层水经吕宋海峡流出,汇入黑潮主干;夏末冬初,黑潮主干经过东海时明显呈弯曲流动;2003年春季,日本以南海域黑潮弯曲不明显;台湾东北部海域存在一个强反气旋涡;表层海水的温度日变化和季节变化明显,在浮标漂移路径呈反气旋或气旋式转动的区域,对应出现了表层水温的高、低温区。     

台湾东北部黑潮表层水入侵东海陆架的季节变化规律

基于1998～2011 年进入台湾东北部的WOCE-SVP(World Ocean Circulation Experiment -Surface Velocity Programme)计划的Argos 浮标运行轨道数据, 分析了台湾东北部的环流特征、黑潮表层水入侵东海陆架的季节变化规律。结果表明: 在春夏季, 黑潮表层水入侵仅限于陆架外缘, 而在秋冬季, 黑潮表层水可深入东海陆架或进入台湾海峡。自黑潮区入侵至100 m 和150 m 等深线的浮标数量在秋冬季较多, 春夏季较少。台湾海峡的浮标轨迹在春夏季几乎皆为北向, 在秋冬季皆为南向。在秋季, 东海中部和南部陆架会在黑潮西侧出现逆流和涡旋。可见, 台湾东北部环流具有显著的季节特征; 黑潮表层水入侵东海陆架在秋冬季较强, 春夏季较弱。本研究采用最新的Argos 浮标数据, 揭示了台湾东北部黑潮入侵东海陆架的季节变化规律。     

Typical Surface Seasonal Circulation in the Indian Ocean Derived from Argos Floats

This study investigates the surface circulation in the Indian Ocean using Argos float data over the period 1979-2011.The Argos observations manifest some new phenomena.The climatological annual mean circulation shows that the surface current becomes much stronger after turning around in shore in the western Indian Ocean.In the tropical Indian Ocean,the Great Whirl(GW) to the east of Somalia develops quickly in spring(April-May) as the monsoon reverses to move northward,becoming strongest in summer(June-September) and disappearing in autumn(October-November).The west end of the Agulhas retroflection can reach 18°E,and it exhibits a seasonal variation.At approximately 90°E,the Agulhas Return Current combines with the eastward South Atlantic Current and finally joins the Antarctic Circumpolar Current.     

Argos卫星发射平台研究与Argos通讯系统应用

目前Argos卫星通讯系统在国际上得到越来越广泛的应用。要使Argos系统这样的国外先进技术手段真正为我所用,必须掌握Argos系统发射机终端的使用技术。文中结合“十五”863计划“极区卫星跟踪水文气象要素探测技术”(简称“极区浮标”)工程样机研制过程,对Argos通讯技术研究情况及实际应用情况做一简介。     

The Faraoni event (latest Hauterivian) in ichnological record: The Río Argos section of southern Spain

The Early Cretaceous (latest Hauterivian) Faraoni Oceanic Anoxic Event (F-OAE) in the Río Argos section (Caravaca region, southern Spain), the candidate for the Global Boundary Stratotype Section and Point (GSSP) of the Hauterivian–Barremian transition, has been studied. Its ichnological bed-by-bed analysis allows for interpretation of oxygenation changes through the Faraoni Level interval and improvement upon previous characterization of oxygen conditions prior, during and after the F-OAE. The trace fossil assemblage belongs to the Zoophycos ichnofacies and it includes Chondrites intricatus, Chondrites targionii, Halimedides isp., Palaeophycus isp., ?Patagonichnus isp., Planolites isp., Rhizocorallium isp., Taenidium isp., Thalassinoides isp., Trichichnus linearis, Zavitokichnus fusiformis, and Zoophycos isp. Their diversity in particular beds fluctuates. Beds with four to six ichnotaxa reflect a multi-tiered macrobenthic trace maker assemblage living in good oxic and trophic conditions. In one bed below and one bed above the Faraoni Level (both marls without primary lamination), there are only two or three, mostly opportunistic ichnotaxa (Trichichnus, Chondrites, Planolites). They record dysoxic conditions. At the base of the Faraoni Level, one thicker and two thinner beds of marly mudstones (21.2 and 3.5 cm thick, respectively) are characterized by primary lamination. At the top and in the basal part of the thicker bed and in the thinner beds some trace fossils are present. These beds were deposited under anoxic conditions and later colonized by trace makers either from overlying beds deposited under oxic conditions or from the level of a greenish lamina in the lower part of the thicker bed, recording short episodes of dysoxic conditions. The thinner anoxic beds are separated by marls deposited under dysoxic conditions.     

福岛核泄漏污染物漂移轨迹影响分析

日本东北部海域地震引发的海啸造成福岛第一核电站核泄漏事故,已经成为全世界关注的环境问题,大量受污染海水排人太平洋.基于北太平洋多年Argos漂流浮标海流资料在去除涡旋运动的基础上进行了分析,分段计算了污染海水前锋到达北太平洋不同区域的路径及时间,并与日本公布的计算结果进行了比较,结果表明二者之间存在较大差异.