东海黑潮温、盐度与中国东部气温和降水的相互关系

采用东海黑潮主流段长时间序列的实测温盐资料,研究了东海黑潮上层温度、上层盐度的变化及其与中国东部降水和地面气温的关系.结果表明,在过去50 a内,东海黑潮上层海温呈上升趋势,而上层盐度略呈下降趋势.东海黑潮上层海温和我国东部地面气温的关系在冬季十分密切,呈现出大面积显著的正相关,这与冬季南下冷空气的整体降温作用有关.夏季,长江中下游江水的增多致使大量长江冲淡水入海,可能是导致黑潮上层水盐度下降的一个原因,此时东海黑潮上层盐度与我国大陆东部降水呈负相关.     

东海黑潮表层盐度分布特征及其影响因素

利用美国国家海洋大气管理局2007年发布的全球海域温、盐数据库资料,美国地球物理数据中心2006年发布的海底地形数据库资料以及日本海洋科学与技术机构2003年发布的1997—2002年东海地区月平均降水量资料,研究东海黑潮表层盐度的月季分布特征,并分析其影响因素。结果表明,东海黑潮表层盐度存在明显的月季变化特征。总体而言,12月至次年3月表层盐度高,6—9月表层盐度低,4、5月和10、11月为过渡阶段;表层盐度高值分布在东海黑潮主段靠近东边界一侧;6—9月入口段的表层盐度高于出口段的表层盐度,其他月份入口段的表层盐度低于出口段的表层盐度。东海黑潮表层盐度主要受表层温度、降水、径流的影响。冬、春、秋季的表层盐度分布在黑潮主段靠近陆架一侧区域受表层温度影响大;降水对东海黑潮表层盐度产生局部小范围的影响,时间主要集中在1月和6—8月份,区域分布在低纬25°N以南和30°N附近。长江冲淡水夏季对东海黑潮表层盐度的影响大于其他季节对东海黑潮表层盐度的影响,7月长江径流量达到最大值时,对应的黑潮扇形区的盐度最低。     

东海带鱼(Trichiurus haumela)渔获量与邻近海域水文环境变化的关系

利用35年的东海区带鱼年渔获量资料与长江径流及东海温、盐断面资料、SST和黑潮流量资料，分析了东海渔获量年际变化与海洋环境的关系。结果表明，东海渔获量与长江径流和黑潮暖流的变化有密切的关系，长江径流量大时，东海渔获量高；反之，则低。1960年以来东海区渔获量的4次长期波动与长江径流的年代际变化基本一致。东海渔获量的丰、欠与黑潮(流量)的强、弱呈反位相变化，秋季的黑潮流量与渔获量的变化关系尤其显著；黑潮强(弱)时，东海渔获量低(高)。受长江径流和黑潮的影响，渔获量与盐度的高相关区夏季位于长江口区，秋季则位于黑潮左侧的盐锋内；东海渔获量高(低)分别与区域内盐度的低(高)变化相一致。东海区渔获量与不同季节SST变化的高相关区(即渔场区)关系密切，冬季(2月)位于东海北部的大沙渔场，春(5月)、夏季(8月)位于长江口舟山渔场，秋末初冬(12月)位于舟山及陆架暖流区，渔获量丰年与渔场区SST正异常相对应。     

冬季东海黑潮海-气热量交换对长江中下游汛期降水的影响

黑潮海区的海-气热量交换,表层水温及热含量的变异对大气环流和大陆旱涝的影响已有论述。本文的目的在于分析东海黑潮海区的海-气热量交换特征及其与整个黑潮的关系,探讨它与长江中下游降水的联系,进而计算比较东海嵊山站多年海-气热量交换的特性,得到了有预报意义的指标。一、东海黑潮冬季海-气热量交换的年际变化特性及其与整个黑潮的关系作者在分析东海黑潮海区的海-气热量收支的年平均状况和季节变化特征时指出,10—3月海-气之间的热量比较显著,特别是在严冬季节。据此,本文只着重讨论东海黑     

中国东部边缘海冬季硅酸盐的分布特征及主要来源

利用2007年1～2月的调查资料,分析讨论了中国东部陆架边缘海(南黄海、东海)冬季硅酸盐的分布特征及其主要影响因素。结果表明:近岸海域硅酸盐的高值区位于受长江冲淡水影响的区域;东海的硅酸盐浓度高于南黄海。长江冲淡水和黑潮水是影响东海和南黄海硅酸盐分布的主要因素。黑潮中层水是东海陆架区硅酸盐的主要来源。     

东海黑潮上层环流季节、年际变化与局地风应力关系

利用SODA资料,选取东海PN断面,计算了东海黑潮上层质量输送量的季节、年际变化,并分析其变化周期:其季节变化是夏季最大,冬季最小;普遍存在着2～4 a的年际变化周期,更低频的年际变化周期在1970年代末由20 a减小到8 a左右.用矢量EOF方法对东海的局地风应力场进行分析,发现经向风应力的变化在东海风应力变化中占主导地位.计算东海黑潮区域的平均经向风应力,发现与PN断面上层输送量的季节变化类似,也具有2～4 a的年际变化周期.局地经向风应力的季节变化与东海黑潮上层质量输送量的季节变化关系密切(92%),而与下层质量输送量相关系数只有24%.     

冬季东海黑潮上层水变化特征的分析

东海黑潮水团是东海海域的主要水团。夏季,东海黑潮水团一般划分为四层结构:黑潮表层水、黑潮次表层水、黑潮中层水和黑潮深层水。在冬季,由于大陆沿岸水系势力减弱,以及强烈的表层冷却产生的垂直对流作用,使黑潮表层水变性而和次表层水融为一体,从而使海面至400米层左右的黑潮水体呈现高盐特征。因此,冬季的东海黑潮水团变为三层结构,即黑潮上层水、黑潮中层水和黑潮     

东海G断面平均温、盐度变化与厄尔尼诺关系的初步分析

本文试图利用位于东海黑潮区G断面温、盐度的多年观测资料,对该断面平均温、盐度变化与厄尔尼诺的关系进行了分析,以期有助于研究黑潮对我国东海及邻近海域环流和沿海气候的影响。 Ⅰ.资料来源及统计方法 由于采用的划分标准和指数不同,因而对     

南黄海和东海海水18O的组及其意义 O的组成及其意义

对2006年夏季采自南黄海和东海的海水进行了18O同位素组成的分析,结合温度与盐度的分布,探讨了影响研究海域海水δ18O分布的主要因素。结果表明,南黄海和东海海水的δ18O与盐度之间具有良好的线性正相关关系,据此确定出夏季黑潮水和陆地径流水的特征δ18O值分别为0.20‰—0.45‰和9.85‰。依据海水δ18O的分布,探讨了黑潮水、长江冲淡水和黄海冷水团对研究海区δ18O分布的影响,结果显示,夏季黑潮水仅影响到台湾东北部陆架坡折以外的海域,其影响路径可能以气旋式涡旋的形式出现;在长江口附近海域,长江径流水进入东海后,对长江口东北部海域的影响范围较其南部更为宽广,可到达济州岛西南部。在南黄海海域,海水δ18O的分布可清晰指示出南黄海冷水团的位置,黄海冷水团的形成可能与冬季的黄海暖流具有一定的联系。     

冬季中纬度海气相互作用与长江中下游汛期旱涝预测

中纬度海洋的热力状况对大气环流的维持和变化起着重要的作用,尤其在冬季。汛期的研究表明,冬季黑潮海域海表面水温(SST)与长江中下游和华北平原汛期降水有密切的关系(中国科学院大气物理研究所长期预报组,1978),夏季阿留申海域的SST异常与北太平洋上空大气环流场和后期秋季美国的气温和降水亦存在有意义的关系(Namias,1976)。赵永平(1986a;赵永平, McBean,1996)和Zhao and McBean(1989)曾用北太平洋海洋对大气加热场资料详细地分析了其时空分布特征,揭露了黑潮及邻近海域海洋异常加热对同期和后期半年至一年北半球大气环流的影响事实,并提出用海洋异常加热对同期和后期大气环流作用的反相性假说来进行解释。以上研究表明,冬季中纬度海洋异常加热与大气环流的异常和我国汛期旱涝之间存在一定的联系。 冬季黑潮和湾流海域是中纬度海洋的两个巨大热源,它们对同期和后期大气环流有重要影响。本文研究了冬季中纬度黑潮和湾流海域海洋异常加热对夏季副热带高压和中高纬度西风环流的影响,讨论了长江中下游汛期旱涝前期冬季和同期大气环流型。结果表明,冬季东亚和北美冷空气都强时,黑潮和湾流海域对大气异常多加热,夏季西太副热带高压、乌山和鄂海阻塞高压多趋减弱,中纬环流平直,形成长江中下游偏旱的环流形势；反之,西太副热带高压、乌山和鄂海阻塞高压多趋加强,中纬槽脊系统明显,形成长江中下游偏涝的环流场。本文还对可能的物理过程进行了讨论。     

The dependence of precipitation on wind direction over the Kuroshio front in the winter East China Sea

This study investigates atmospheric responses to the directions of surface wind over the Kuroshio front in the East China Sea, using wintertime satellite-derived data sets. Composite maps of sea surface temperature, wind speed, precipitation, turbulent heat flux, surface wind divergence, and the curl of wind vectors above the atmospheric boundary layer are depicted based on the classification of intense northeasterly (along the front) and northwesterly (across the front) winds over the East China Sea. When northeasterly winds prevail, considerable precipitation occurs on the offshore side of the Kuroshio front, in contrast to periods when northwesterly winds prevail. First, the northeasterly winds strengthen above the front because of the downward transfer of momentum from the fast-moving air at higher levels and/or an adjustment of sea level pressure over the oceanic front, although the process by which the influence of the Kuroshio penetrates beyond the marine atmospheric boundary layer remains unclear. Second, a cyclonic vortex forms above the marine atmospheric boundary layer (at 850-hPa height) on the offshore side of the front, and thereafter, surface wind convergence via Ekman suction (hence, enhanced precipitation) occurs over the East China Sea shelf breaks. The northeasterly winds blow over the East China Sea when the Aleutian Low retreats to the east and when high sea level pressure covers the northern Sea of Japan.     

东海西部陆架海域水团的季节特征分析

On the basis of the CTD data and the modeling results in the winter and summer of 2009, the seasonal characteristics of the water masses in the western East China Sea shelf area were analyzed using a cluster analysis method. The results show that the distributions and temperature-salinity characteristics of the water masses in the study area are of distinct seasonal difference. In the western East China Sea shelf area, there are three water masses during winter, i.e., continental coastal water（CCW）, Taiwan Warm Current surface water（TWCSW） and Yellow Sea mixing water（YSMW）, but four ones during summer, i.e., the CCW, the TWCSW, Taiwan Warm Current deep water（TWCDW） and the YSMW. Of all, the CCW, the TWCSW and the TWCDW are all dominant water masses. The CCW, primarily characterized by a low salinity, has lower temperature, higher salinity and smaller spatial extent in winter than in summer. The TWCSW is warmer, fresher and smaller in summer than in winter, and it originates mostly from the Kuroshio surface water（KSW） northeast of Taiwan, China and less from the Taiwan Strait water during winter, but it consists of the strait water and the KSW during summer. The TWCDW is characterized by a low temperature and a high salinity, and originates completely in the Kuroshio subsurface water northeast of Taiwan.     

Characteristics of variations of water properties and density structure around the Kuroshio in the East China Sea

Quarterly data of CTD at the PN line in the East China Sea during 1988–94 were analyzed to examine the variations of water properties and density structure in relation to the Kuroshio. The Kuroshio flows over the continental slope at the PN line. Water properties in the surface layer less than 100 db change greatly and show a clear seasonal cycle, while those in the subsurface layer are much less variable. The small isobaric variations in the subsurface layer are almost due to the vertical movement of isopycnals, on which the water properties vary little. The subsurface variations of salinity, temperature and isopycnal depth are classified into four groups occurring in the four regions, divided vertically by the middle of the main pycnocline and horizontally by the offshore edge of the Kuroshio, named Groups 1 (upper Kuroshio), 2 (upper offshore region), 3 (lower Kuroshio), and 4 (lower offshore region). The difference in averaged isopycnal depth between Groups 1 and 2 (3 and 4) is highly correlated with the vertical shear of the Kuroshio velocity in the upper (lower) pycnocline. The isopycnal depth of Groups 1 and 3 has little annual cycle (with large intraseasonal variations in Group 3), while that of Groups 2 and 4 shows a clear seasonal variation with the minimum in fall. As a result, the Kuroshio velocity is smallest in fall almost every year, although the amplitude of seasonal variation and the season of maximum velocity are different from year to year. Interannual variations of isopycnal depth are characterized by a large amplitude of Group 2 and an opposite phase between Groups 3 and 4, so that the variations of difference in isopycnal depth between Groups 1 and 2 and Groups 3 and 4, i.e., the upper and lower shear of the Kuroshio velocity, are comparably significant.     

东海黑潮活跃区表层流场的半年内时间尺度变化研究

利用高时空分辨率的资料,对东海黑潮表层海流的半年内时间尺度变化特征进行了分析研究,得到主要以下结论:(1)东海黑潮表层海流在台湾东北海区和吐噶喇海峡附近海区存在着最为显著的变化;(2)那里的表层海流都存在半年内时间尺度的变化,其谱峰主要在50~70d及90~140d两个频段内,两个准周期变化的基本特征都是异常气旋涡和反气旋涡的准周期转换;(3)异常气旋涡和反气旋涡的活动都与东海黑潮在两个海区的流轴变化相联系,气旋涡与黑潮流轴在该海区的向东南退缩相伴,而反气旋涡与黑潮流轴在该海区的向西北推进相伴;(4)初步分析表明,在台湾东北海域导致50~70d变化的异常涡旋主要源于黑潮自身存在的中尺度过程,而90~140d的变化则主要受从台湾以东传来的中尺度涡影响。类似地,吐噶喇海峡附近的黑潮海流同样在50~70d及90~140d两个频段内存在显著的准周期变化,回归分析表明,导致50~70d变化主要源于上游黑潮海流的中尺度过程,而90~140d的变化则主要受琉球群岛以东传来的中尺度涡影响。     

Winter Distribution of Diatom Assemblages in the East China Sea

We examined the spatial distributional relationships between diatom assemblages and water types during the winter in the East China Sea. Principal component analysis was used to identify two water types and two diatom assemblages in the study area. Coastal water types along the mainland China coastline had low temperature and salinity levels, but high nitrate levels. The shelf-mixing water type in the rest of the study area had higher temperatures and salinities and lower levels of nitrate. Diatom assemblage distribution was not spatially consistent with water type. The Kuroshio assemblage had a large standing stock, distributed along the surface of the shelf break. This assemblage is likely the result of Kuroshio surface water coming into contact with nutrient-rich water in the shelf area, triggering proliferation of certain diatom species. A background assemblage with low standing stock level persisted over the entire study area in both coastal water and the shelf-mixing water types. Our results support previous research: the background assemblage is due to poor growth conditions such as the convection of water during winter; there were no significant seasonal variations in the species composition.     

Intrusion of less saline shelf water into the Kuroshio subsurface layer in the East China Sea

The possible origin and cause of the less saline shelf water detected in the Kuroshio subsurface layer around the shelf edge of the East China Sea are investigated using observational results obtained in May 1998–2001 in conjunction with a dataset archived by Japan Oceanographic Data Center and a numerical model. The observations show that subsurface intrusions of less saline water are always detected in May in layers above 24.5σθ isopycnal surface, and that salinity inversions (i.e., areas in which the less saline water lies beneath the saline water) are detected around the trough of the Kuroshio frontal eddy (or wave). Analyses of the archived dataset reveal that the isopycnal surface of 24.5σθ is the deepest layer of the Kuroshio pycnocline outcropping to the sea surface on the shallow shelf in early spring. Outcropping isopycnals above 24.5σθ encounter a less saline water plume originating from the Changjiang, especially in the western East China Sea. Thereafter, the less saline water moves along isopycnal layers and reaches the Kuroshio front around the shelf edge. Numerical models demonstrate that, when the frontal wave captures the less saline water, the shelf water takes the form of a salinity inversion in the trough because isohalines in the frontal wave have a phase lag between the upper and lower layers in consequence of the baroclinic instability.     

Intrusion of Kuroshio water onto the continental shelf of the East China Sea

As a fundamental study to evaluate the contribution of the Kuroshio to primary production in the East China Sea (ECS), we investigated the seasonal pattern of the intrusion from the Kuroshio onto the continental shelf of the ECS and the behavior of the intruded Kuroshio water, using the RIAM Ocean Model (RIAMOM). The total intruded volume transport across the 200m isobath line was evaluated as 2.74 Sv in winter and 2.47 Sv in summer, while the intruded transport below 80m was estimated to be 1.32 Sv in winter and 1.64 Sv in summer. Passive tracer experiments revealed that the main intrusion from the Kuroshio to the shelf area of the ECS, shallower than 80m, takes place through the lower layer northeast of Taiwan in summer, with a volume transport of 0.19 Sv. Comparative studies show several components affecting the intrusion of the Kuroshio across the 200 m isobath line. The Kuroshio water intruded less onto the shelf compared with a case without consideration of tide-induced bottom friction, especially northeast of Taiwan. The variations of the transport from the Taiwan Strait and the east of Taiwan have considerable effects on the intrusion of the Kuroshio onto the shelf.     

台湾岛东西两岸的海流

本文收集、整理和分析台湾岛东、西两岸的海流资料，获得以下主要结果；（１）台湾东岸的黑潮路径，无论是表层或深层，都是冬季偏酉（距台湾东岸较近），夏季偏东，春、秋两季的介于冬、夏季的路径之间。（２）台湾东岸黑潮的流速，具有夏、春强而冬弱的特点。（３）台湾西岸近海的海流，除表层受风的影响较大外，１０ｍ层开始，尤其是近底层，冬、夏两季皆以北向或东北向流为主，呈现出一派北向流的路径。这与传统观念不同。     

Kuroshio intrusion into the South China Sea with an anticyclonic eddy: evidence from underwater glider observation

In this study, high-resolution temperature and salinity data obtained from three Sea-Wing underwater gliders were used together with satellite altimeter data to track the vertical thermohaline structure of an anticyclonic eddy that originated from the loop current of the Kuroshio southwest of Taiwan, China. One of the gliders crossed the entire eddy and it observed a remarkable warm anomaly of as much as 3.9℃ extending to 500 dbar from the base of the mixed layer. Conversely, a positive salinity anomaly was found to be above 200 dbar only in the anticyclonic eddy, with a maximum value of >0.5 in the mixed layer. Below the mixed layer, water of higher salinity (>34.7) was found, which could have been preserved through constrained vertical mixing within the anticyclonic eddy. The salinity in the upper layer of the anticyclonic eddy was much similar to that of the northwestern Pacific Ocean than the northern South China Sea, reflecting Kuroshio intrusion with anticyclonic eddy shedding from the loop current.     

Characteristics of outer shelf water in the East China Sea

Water mass properties along cross-sections of the Kuroshio in the East China Sea (ECS) are investigated in detail. We used temperature, salinity and dissolved oxygen data from 2000 and 2002, together with historical temperature and salinity data from 1987 to 2004. Water properties were divided into two groups: high and low salinities or oxygen at temperatures warmer than 15 and 12 °C, respectively. We found the existence of outer shelf water W2, as defined by clear modes in frequency distributions of salinity and oxygen within various temperature segments. The outer shelf water was different from both Kuroshio Tropical Water (KTW) and coastal water. We mapped horizontal and vertical distributions of W2, along with W1 and KTW. The outer shelf water was distributed with density σ _t = 22.5–25.5 over a relatively broad area, from the outer continental shelf to the continental slope, particularly in autumn. Vertical distribution of the water suggests that W2 spread from the outer shelf to just the shelf side of the Kuroshio Current velocity maximum. Seasonal variations are examined with historical data along PN section over 17 years, and suggest that the appearance of W2 is distinct in summer and autumn. By comparing temperature–salinity (T–S) diagrams from Taiwan Strait and east of Taiwan, the outer shelf water (W2) originates from South China Sea Tropical Water (SCSTW), as suggested by Chen, J Geophys Res 110:C05012 (2005). The present study of the ECS clearly shows that SCSTW is transported along the east coast of Taiwan or through the Taiwan Strait into the ECS. It then spreads over a relatively wide area from the outer shelf to just the shelf side of the Kuroshio axis, and there is some horizontal mixing between SCSTW and KTW around the shelf break.