南海民都洛岛西南暖池的季节变化研究

南海暖池作为影响我国东南部地区气候变化的重要因素,研究其多时间尺度变化特征及动力机制对于更加准确预报我国天气变化具有重要意义。结合海表面温度卫星观测资料和海表面再分析数据,识别和研究了南海民都洛岛西南暖池的季节变化特征,并利用数值模式探讨了其强迫机制。暖池位于民都洛岛西南方向约100 km范围内,中心位置在120.5°E, 12.5°N。暖池整个季节变化过程可分为发展期(10～11月)、成熟期(12～2月)、衰退期(3～5月)、消失期(6～9月)4个阶段:11月份暖池与南北两侧冷水温差达到0.5°C,暖池结构初步形成; 2月份温差达到1.1°C (南侧)和0.7°C (北侧),暖池最强;3月份暖池开始衰退,到6月份完全消失。进一步研究表明,该暖池的形成与地形引起的民都洛岛附近海域潜热通量的空间差异有关:冬季盛行的东北季风被民都洛岛上的高海拔山脉阻挡,在民都洛岛西南背风侧形成低风速区,而在南北两侧形成风激流(风速极大值区)。风速的空间差异引起了海表面潜热通量的差异,导致民都洛岛背风侧的潜热通量较周围海域要小,海表面温度较周围海域要高,从而导致了暖池的形成。     

夏季巴拉望岛西北部海域净热通量的时空变化特征和形成机理初析

利用OAFLUX气候态月平均热通量资料及TMI云量、降雨、SST和QuikScat风场资料,对南海、特别是巴拉望岛西北海域净热通量的时空特征进行了深入分析.研究发现,夏季在巴拉望岛西北海域存在一局域净热通量极小值区,在7月份该海域海洋甚至呈现失热达20 W/m2情况.分析认为该局地净热通量异常可能与南海暖水的发生、发展有关,即由于西南季风爆发,巴拉望岛西北海域对流加强,一方面,蒸发增大使得潜热增大、云量增多,导致入射太阳短波辐射的减少;另一方面,降水的增大使得该海域出现障碍层现象,障碍层导致的局地海温正反馈进一步增强了局地对流,从而加剧海洋失热过程,促成了巴拉望岛西北海域净热通量局地异常的出现.进一步的经验正交模态（EOF）分析表明,在季节变化尺度上,南海净热通量的第一模态（89.1%）呈同位相变化,反映了南海受冬、夏季风的交替驱动特征;其中南海北部（海南岛至台湾海峡南段的带状海域）为振幅最大区,这与该海域存在年平均最大风速有关;第二模态（10.0%）以吕宋岛至雷州半岛一线为界,南北两侧反相,并具有显著的局域特征;不仅反映了黑潮入侵与南海环流的季节变化,而且还发现巴拉望岛西北海域存在一局地极值域,对应夏季净热通量异常区.     

1998年春夏南海温盐结构及其变化特征

利用1998年5～8月“南海季风试验”期间“科学1”号和“实验3”号科学考察船两个航次CTD资料,分析了1998年南海夏季风暴发前后南海主要断面的温盐结构及其变化特征.观测发现,南海腹地基本被典型的南海水团所控制,但在南海东北部尤其是吕宋海峡附近,表层和次表层水明显受到西太平洋水的影响.季风暴发以后,南海北部表面温度有显著升高,升幅由西向东递减,而南海中部和南部表面温度基本没变,这使得南海北部东西向温度梯度和整个海盆南北向温度梯度均减小.北部断面表层盐度普遍由34以上降低到34以下,混合层均有所发展,是季风暴发后降水和风力加剧的结果.观测期间黑潮水跨越吕宋海峡的迹象明显但变化剧烈.4～5月,黑潮次表层水除在吕宋海峡中北部出现外,在吕宋岛以西亦有发现,表明有部分黑潮水从吕宋海峡南端沿岸向西进而向南进入南海.6～7月,次表层高盐核在吕宋海峡中北部有极大发展,但在吕宋岛以西却明显萎缩;虽然看上去黑潮水以更强的流速进、出南海,但对南海腹地动力热力结构的影响未必更大.一个超过34.55的表层高盐水体于巴拉望附近被发现,似与通过巴拉望两侧水道入侵南海的西太平洋水有关.     

Calculation of circulation in the South China Sea during summer of 2000 by the modified inverse method

On the basis of hydrographic data obtained in August 2000 cruise, the circulation in the South China Sea (SCS) is computed by the modified inverse method in combination with SSH data from TOPEX/ERS-2 analysis. For study of the dynamical mechanism, which causes the pattern of summer circulation in the SCS, the diagnostic model (Yuan et al. 1982. Acta Oceanologica Sinica,4(1):1-11; Yuan and Su. 1992. Numerical Computation of Physical Oceanography.474-542) is used to simulate numerically the summer circulation in the SCS. The following results     

南海的季节环流─TOPEX/POSEIDON卫星测高应用研究

应用1992～1996年的TOPEX/POSEIDON卫星高度计遥感资料,研究了冬、夏季风强盛期多年平均的南海上层环流结构。研究结果表明,南海上层流结构呈明显的季节变化,在很大程度上受该海区冬、夏交替的季风支配。冬季总环流呈气旋型,并发育有两个次海盆尺度气旋型环流;夏季总环流大致呈反气旋型、但在南海东部18°N以南海域未见明显流系发育。研究还表明,南海环流的西向强化趋势明显,无论冬、夏在中南半岛沿岸和巽他陆架外缘均存在急流,其流向冬、夏相反,是南海上层环流中最强劲的一支。鉴于该海流的动力特征与海洋动力学中定义的漂流不同,有相当大的地转成分,建议称为“南海季风急流(South China Sea MonsoonJet)”.冬季南下的季风急流在南海南部受巽他陆架阻挡折向东北,沿加里曼丹岛和巴拉望岛外海有较强东北向流发育。夏季北上的季风急流在海南岛东南分为两支:北支沿陆架北上,似为传统意义上的南海暖流;南支沿18°N向东横穿南海后折向东北;二者之间(陆架坡折附近)为弱流区。两分支在汕头外海汇合后,南海暖流流速增强。就多年平均而言,黑潮只在冬季侵入南海东北部,并在南海北部诱生一个次海盆尺度的气旋型环流,这时南海暖流只出现在汕头以东海域.夏季南海北部完全受东北向流控制,未见黑潮入侵迹象.用卫星跟踪海面漂流浮标观测进行的对比验证表明,以上遥感分析结果与海上观测一致。     

南海暖水的季节变化特征及数值模拟

根据Ｌｅｖｉｔｕｓ资料,对具有立体结构的南海暖水给出了定义,分析发现：南海暖水的季节变化过程可分为发展、维持、退缩和消失４个阶段;就气候平均而言,南海暖水在季节变化中始终保持西北部浅、东南部深的特点;南海暖水的深度与同期温跃层上界的深度在空间分布特征与季节变化趋势上都基本类似。采用“ｉｎｔｅｒｍｅｄｉａｔｅ”模式模拟了南海暖水的范围和厚度,结果表明发展阶段的南海暖水范围和厚度的增长主要是因为南海地     

夏季越南东北外海暖水的时空变化特征及其机理研究

Due to orographic blockage, a weak wind wake occurs in summer off northeast Vietnam in the South China Sea. Under the wind wake, warm water is observed from both high-resolution satellite data and hydrographic observations. The wake of warm water forms in June, continues to mature in July and August, starts to decay in September, and disappears in October. The warm water wake also shows robust diurnal variation – it intensifies during the day and weakens in the night. Warm water wakes can be generated through wind-induced mixing and thermal(latent heat flux) processes. In this paper, a mixed layer model is used to evaluate the relative importance of the two processes on seasonal and diurnal timescales, respectively. The results demonstrate that thermal processes make a greater contribution to the wake than wind-induced mixing processes on a seasonal timescale, while the warm water wake is dominated by wind-induced mixing processes on a diurnal timescale.     

基于OC-CCI数据的南海高叶绿素a浓度水域面积的时空变化研究*

浮游植物是海洋生态系统食物链的基础组成, 并通过光合作用影响着海表二氧化碳通量变化。文章基于高叶绿素a浓度水域面积指标构建南海浮游植物生物量的估算体系。利用遥感数据, 采用经验正交函数分解插值方法, 重构长时间序列的南海叶绿素a浓度场, 并研究了南海高叶绿素a浓度水域面积特征的时空分布。结果发现: 高叶绿素a浓度水域面积变化有着显著季节特征, 在冬季面积达到最大值, 在夏季达到最小值, 但是该水域对应的叶绿素a浓度却在冬季达到最小值, 在夏季达到最大值, 这一特征可能是由于风驱动的海表动力过程使得海表叶绿素重新分布; 空间分布上, 高叶绿素a浓度水域常年存在于海岸附近, 特别是在中国沿海、越南沿岸、泰国湾以及婆罗洲岛附近。在巽他陆架与湄公河口东部中央海盆, 高叶绿素a浓度区域面积呈年际变化。受厄尔尼诺调控的南海季风, 导致不同年份湄公河口东南沿海存在不同程度的北部冷水侵入, 北部冷水入侵可能是引起局地浮游植物生物量增减的原因。     

基于观测的南海越南沿岸次表层涡旋

In this study, subsurface eddies near the Vietnam coast of the South China Sea were observed with in situ observations, including Argo, CTD, XBT and some processed and quality controlled data. Based on temperature profiles from four Argo floats near the coast of Vietnam, a subsurface warm eddy was identified in spring and summer. The multi-year Argo and Global Temperature and Salinity Profile Programme(GTSPP) data were merged on a seasonal basis based on the data interpolating variational analysis(DIVA) method to reconstruct the three-dimensional temperature structure. There is a warm eddy in the central subsurface at 12.5°N, 111°E below300 m depth in spring, which does not exist in autumn and is weak in winter and summer. From CSIRO Atlas of Regional Seas(CARS) and Generalized Digital Environment Model(GDEM) reanalysis data, this subsurface warm eddy is also verified in spring.     

北部湾环流和沉积物输运的数值模拟

研究环流和沉积物输运对北部湾的环境保护和资源开发十分重要。本文使用区域海洋模型（ROMS）,研究了北部湾海域的季节环流、沉积物输运以及长期的地形演变过程。展示了湾内冬季和夏季都存在逆时针环流,冬季的风生环流比夏季强的特征。悬沙浓度较大值主要分布在琼州海峡、海南岛西侧海域,以及越南沿岸、雷州半岛沿岸等近岸地区。沉积物在琼州海峡附近表现为在冬季由东向西输运,夏季则相反;在琼州海峡西口处,沉积物全年以西向输运为主。结果显示,北部湾内沉积物输运主要由潮流引起的再悬浮控制。侵蚀和淤积的分布模式为：（1）湾内大部分区域侵蚀淤积不明显,（2）琼州海峡两侧口门附近淤积比较明显,（3）琼州海峡内深槽侵蚀严重,（4）海南岛西侧海域存在侵蚀和淤积交替发生区域。     

Surface layer temperature inversion in the Arabian Sea during winter

Surface layer temperature inversion in the south eastern Arabian Sea, during winter has been studied using Bathythermograph data collected from 1132 stations. It is found that the inversion in this area is a stable seasonal feature and the occurrence is limited to the coastal waters. The inversion layer is found to have thickness varying from 10 to 80 meters and gradient of 0.0–1.2°C. The causative factor for the inversion is identified to be the winter-time surface-advection of cold less saline Bay of Bengal water over the warm saline Arabian Sea water along the west coast of India. Finally, the possible forcing mechanism for such an advection was examined using a hydrographic section and wind observations along the west coast of India.     

Evolution of a coastal upwelling event during summer 2004 in the southern Taiwan Strait

A coastal upwelling event in the southern Taiwan Strait (STWS) was investigated using intensive cruise surveys (four repeated transects in a month) and satellite data in July and early August 2004.The extensive upwelling-associated surface cold water was first observed in early July (～2.0×10 4 km 2) along the STWS coast.Then,the cold surface water reduced in size by ～50% with decreased chlorophyll concentrations after 15 days,indicating the weakening of the upwelling event.At the end of July,the cold surface water disappeared.The temporal variations of the surface cold water and the 3-D hydrography around Dongshan Island are thought to be mainly attributed to the weakened upwelling-favorable southwestern wind,the asymmetric spatial structure of the wind field and the intrusion of warm water from the northern South China Sea.     

加里曼丹岛西北侧低盐水季节变化及机理分析

利用LEVITUS温盐资料、HOAPS降水及蒸发资料以及OFES模式资料等分析加里曼丹岛西北侧表层低盐水的季节变化规律,并使用盐度平衡模式诊断了海面淡水通量、径流、卷挟作用以及平流作用对低盐水变化的贡献.分析表明:加里曼丹西北侧全年均存在1个低盐水团,其季节变化具有"双峰"特征,3月至4月以及10月至11月会发生2次低...     

台湾海峡中、北部海域温、盐度特征

台湾海峡中、北部海域海水温、盐度分布随季风进退而异。东北季风期(10月—翌年5月),进入调查海域的浙闽沿岸水(低温、低盐)顺海域西岸海区南下的同时,在海坛岛外有一分支向东南扩展,其扩展范围随浙闽沿岸水强弱而异,而且在24°30′N,119°30′E附近有海峡暖流水(高温、高盐)向北伸展,它随西南风增强而向北推移。海域温、盐度值自西北向东南递增。西南季风期(6—9月),调查海域基本上为海峡暖流水所控制。在6—8月,海域西岸海区有上升流产生,上升流中心在海坛岛附近。海域盐度值自西北向东南递增,而温度分布趋势与盐度分布相反。 温、盐度的垂直分布大致分均匀型、正梯度型和负梯度型三类。     

台湾海峡及邻近海域海面热量平衡分布特征

本文利用1961—1985年历次台湾海峡及邻近海域水文气象调查资料,计算分析了该海域海面吸收辐射、有效回辐射、蒸发耗热、海-气感热交换的时空分布,给出了该海域热量平衡年平均状况和季节变化特征。     

基于多源融合卫星高度计观测数据的南海海浪有效波高的季节变化研究

The seasonal variability of the significant wave height(SWH) in the South China Sea(SCS) is investigated using the most up-to-date gridded daily altimeter data for the period of September 2009 to August 2015. The results indicate that the SWH shows a uniform seasonal variation in the whole SCS, with its maxima occurring in December/January and minima in May. Throughout the year, the SWH in the SCS is the largest around Luzon Strait(LS) and then gradually decreases southward across the basin. The surface wind speed has a similar seasonal variation, but with different spatial distributions in most months of the year. Further analysis indicates that the observed SWH variations are dominated by swell. The wind sea height, however, is much smaller. It is the the largest in two regions southwest of Taiwan Island and southeast of Vietnam Coast during the northeasterly monsoon, while the largest in the central/southern SCS during the southwesterly monsoon. The extreme wave condition also experiences a significant seasonal variation. In most regions of the northern and central SCS, the maxima of the 99 th percentile SWH that are larger than the SWH theoretically calculated with the wind speed for the fully developed seas mainly appear in August–November, closely related to strong tropical cyclone activities.Compared with previous studies, it is also implied that the wave climate in the Pacific Ocean plays an important role in the wave climate variations in the SCS.     

中国近海海面风场的时空特征分析

本文利用1987年9月—2013年9月连续26 a的多源卫星融合数据,用经验正交函数方法(EOF)分析中国近海海面风场变化特征。分析结果指出中国近海海面风场的第一模态占总方差贡献的63.94%,呈现为冬-夏季风振荡类型,揭示了中国近海风场的季节变化特征;第二模态占总方差贡献的12.35%,呈现为春-秋振荡类型,反映了冬季风和夏季风过渡时期的变化特征;第三模态占总方差贡献的3.49%,呈现出近似半年周期的波动,体现了中国近海风场季节内变化的特征。     

The termination of the Equatorial Undercurrent in the eastern Pacific

The termination of the Equatorial Undercurrent (EUC) in the eastern tropical Pacific has been studied through analysis of the historical hydrographic station data in the region bounded by 5°N, 10°S, 80°W and 100°W. Three distinctive hydrographic features associated with the EUC are used, along with dynamic topography, to trace the mean path of the EUC and to investigate aspects of its seasonal variation. These features are (1) the 13°C thermostad, (2) the high-salinity core, and (3) the high dissolved oxygen concentration tongue.The thermostad is thickest just south of the equator to the west of the Galapagos Islands, with a decreasing maximum extending southeast to the coast of South America near 7°S. The thermostad is poorly developed in the mean near the equator east of the Galapagos Islands. This pattern appears to be produced by convergence of eastward flow in the EUC and in the Southern Subsurface Countercurrent, as the EUC flows southeastward from the Galapagos. This interpretation is supported by the geostrophic flow calculated from the mean dynamic topography. The isolated high-salinity core is found to the south of the equator and is traced all the way to the coast of South America. The high oxygen tongue associated with the EUC splits at the Galapagos, with the southward projecting branch disappearing rapidly as an identifiable feature. The other branch of the tongue continues around the islands to the north and along the equator to the coast of Ecuador. Some evidence of recirculation of EUC water in the South Equatorial Current is seen to the northwest of the Galapagos.A strong seasonal pulsation of the EUC affects these features in a consistent way, with the pulse occurring first west of the Galapagos, and later along the coast. The thermostad first reaches maximum development, and then a pronounced downwelling of the thermocline occurs rapidly, leading to minimum thermostad extent. Associated wtih this downwelling is an eastward protruding high-salinity tongue near the equator which is later seen as an isolated core along the coast at 4°S and 6°S. Pressure gradients along the equator and the coast inferred from dynamic topography suggest that this pulse is associated with an increase in the flow of the EUC, and ultimately the Peru-Chile Undercurrent. The pressure gradient reversal along the equator occurs prior to the annual wind reversal, suggesting that remote forcing plays a role in the seasonal pulse of the EUC in the eastern Pacific.     

风对福建中部沿岸春、夏季水文结构和上升流的影响

本文对台湾海峡西侧海坛岛附近海域风情与附近岸站的风情进行了对比分析,结果表明,海上风情和岸站风情变化基本上是一致的;在不同季风的作用下,海域温、盐度呈现不同类型的分布。风情的短期变化对上升流的强弱变化有一定影响。     

南海海面高度季节变化的数值模拟

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