太平洋—印度洋贯穿流南海分支研究综述          下载免费PDF全文

张晶  魏泽勋  李淑江  王永刚 《海洋科学进展》2014,32(1):107-120

从海洋动力学角度,概述了太平洋-印度洋贯穿流南海分支的主要入流和出流通道—吕宋海峡和卡里马塔海峡的研究现状。太平洋-印度洋贯穿流南海分支是太平洋、南海和印度尼西亚海域进行水体和热盐交换的传输带,对西太平洋、南海、印尼海和东印度洋的环流系统有重要影响。吕宋海峡水交换和卡里马塔海峡贯穿流都呈现冬季大夏季小的季节变化特征,对维持南海的物质、能量和动量平衡起重要作用。太平洋通过吕宋海峡向南海输运水体和热盐,并传递ENSO等气候信号,对南海的环流、水体和海洋环境都产生重要影响。卡里马塔海峡向印度尼西亚海区的水体和热盐输运对印度尼西亚贯穿流有重要意义。太平洋-印度洋贯穿流南海分支和印尼贯穿流的年际变化趋势呈反位相,两者相互调制相互影响,维持了太平洋-印度洋两大洋间的平衡关系,对全球大洋环流的结构和长期的气候变化有重要作用。  相似文献   

西北太平洋累积气旋能量的年代际变化     

王功录  王启  赵海 《中国海洋大学学报(自然科学版)》2014,44(5):17-24

利用1949—2011年CMA-STI热带气旋最佳路径数据集,分析了西北太平洋累积气旋能量(ACE)的年代际变化特征。结果表明,西北太平洋热带气旋(ACE)的年代际变化主要分为1957—1967高值期、1976—1986过渡期和1998—2008低值期。其中强热带风暴(STS)、台风(TY)和超强台风(SuperTY),特别超强台风是决定成分。副热带高压偏弱,垂直风切变偏小,低纬度低空正涡度异常偏东以及低纬度海表面温度(SST)正异常偏东等背景场的年代际特征,有利于形成ACE的年代高值期。  相似文献   

The potential of ocean acidification on suppressing larval development in the Pacific oyster Crassostrea gigas and blood cockle Arca inflata Reeve     

李加琦  蒋增杰  张继红  毛玉泽  卞大鹏  方建光 《中国海洋湖沼学报》2014,32(6):1307-1313

We evaluated the effect of pH on larval development in larval Pacific oyster （Crassostrea gigas） and blood cockle （Arca inflata Reeve）. The larvae were reared at pH 8.2 （control）, 7.9, 7.6, or 7.3 beginning 30 min or 24 h post fertilization. Exposure to lower pH during early embryonic development inhibited larval shell formation in both species. Compared with the control, larvae took longer to reach the D-veliger stage when reared under pH 7.6 and 7.3. Exposure to lower pH immediately after fertilization resulted in significantly delayed shell formation in the Pacific oyster larvae at pH 7.3 and blood cockle larvae at pH 7.6 and 7.3. However, when exposure was delayed until 24 h post fertilization, shell formation was only inhibited in blood cockle larvae reared at pH 7.3. Thus, the early embryonic stages were more sensitive to acidified conditions. Our results suggest that ocean acidification will have an adverse effect on embryonic development in bivalves. Although the effects appear subtle, they may accumulate and lead to subsequent issues during later larval development.  相似文献   

Water discharge variability of Changjiang （Yangtze） and Huanghe （Yellow） Rivers and its response to climatic changes     

张喜林  范德江  王厚杰  杨作升 《中国海洋湖沼学报》2014,32(6):1392-1405

Influences of large-scale climatic phenomena, such as the E1Nifio/La Nifia-Southem Oscillation （ENSO） and the Pacific Decadal Oscillation （PDO）, on the temporal variations of the annual water discharge at the Lijin station in the Huanghe （Yellow） River and at the Datong station in the Changjiang （Yangtze） River were examined. Using the empirical mode decomposition-maximum entropy spectral analysis （EMD- MESA） method, the 2- to 3-year, 8- to 14-year, and 23-year cyclical variations of the annual water discharge at the two stations were discovered. Based on the analysis results, the hydrological time series on the inter- annual to interdecadal scales were constructed. The results indicate that from 1950 to 2011, a significant downward trend occurred in the natural annual water discharge in Huanghe River. However, the changes in water discharge in Changjiang River basin exhibited a slightly upward trend. It indicated that the changes in the river discharge in the Huanghe basin were driven primarily by precipitation. Other factors, such as the precipitation over the Changjiang River tributaries, ice melt and evaporation contributed much more to the increase in the Changjiang River basin. Especially, the impacts of the inter-annual and inter-decadal climate oscillations such as ENSO and PDO could change the long-term patterns of precipitation over the basins of the two major rivers. Generally, low amounts of basin-wide precipitation on interannual to interdecadal scales over the two rivers corresponded to most of the warm ENSO events and the warm phases of the PDO, and vice versa. The positive phases of the PDO and ENSO could lead to reduced precipitation and consequently affect the long-term scale water discharges at the two rivers.  相似文献   

Variability of tropical cyclone in high frequent occurrence regions over the western North Pacific   总被引：1，自引：0，他引：1  

Yuxing Yang  Fei Huang  Faming Wang 《中国海洋大学学报(英文版)》2014,13(3):347-355

In this study, three high frequent occurrence regions of tropical cyclones(TCs), i.e., the northern South China Sea(the region S), the south Philippine Sea(the region P) and the region east of Taiwan Island(the region E), are defined with frequency of TC's occurrence at each grid for a 45-year period(1965–2009), where the frequency of occurrence(FO) of TCs is triple the mean value of the whole western North Pacific. Over the region S, there are decreasing trends in the FO of TCs, the number of TCs' tracks going though this region and the number of TCs' genesis in this region. Over the region P, the FO and tracks demonstrate decadal variation with periods of 10–12 year, while over the region E, a significant 4–5 years' oscillation appears in both FO and tracks. It is demonstrated that the differences of TCs' variation in these three different regions are mainly caused by the variation of the Western Pacific Subtropical High(WPSH) at different time scales. The westward shift of WPSH is responsible for the northwesterly anomaly over the region S which inhibits westward TC movement into the region S. On the decadal timescale, the WPSH stretches northwestward because of the anomalous anticyclone over the northwestern part of the region P, and steers more TCs reaching the region P in the greater FO years of the region P. The retreating of the WPSH on the interannual time scale is the main reason for the FO's oscillation over the region E.  相似文献   

Fully coupled time-domain simulation of dynamic positioning semi-submersible platform using dynamic surface control     

Haizhi Liang  Luyu Li  Jinping Ou 《中国海洋大学学报(英文版)》2014,13(3):407-414

A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning （DP） system. In the control force design, a dynamic model of reference linear drift frequency in the horizontal plane is introduced. The dynamic surface control （DSC） is used to design a control strategy for the DP. Compared with the traditional back-stepping methods, the dynamic surface control combined with radial basis function （RBF） neural networks （NNs） can avoid differentiating intermediate variables repeatedly in every design step due to the introduction of a first order filter. Low frequency motions obtained from total motions by a low pass filter are chosen to be the inputs for the RBF NNs which are used to approximate the low frequency wave force. Considering the propellers’ wear and tear, the effect of filtering frequencies for the control force is discussed. Based on power consumptions and positioning requirements, the NN cen-ters are determined. Moreover, the RBF NNs used to approximate the total wave force are built to monitor the disturbances. With the DP assistance, the results of fully coupled dynamic response simulations are given to illustrate the effectiveness of the proposed con-trol strategy.  相似文献   

Effect of Decadal Changes in Air-Sea Interaction on the Climate Mean State over the Tropical Pacific          下载免费PDF全文

FANG Xiang-Hui  ZHENG Fei 《大气和海洋科学快报》2014,(5):400-405

Collaboration of interannual variabilities and the climate mean state determines the type of E1 Nifio. Recent studies highlight the impact of a La Nifia-like mean state change, which acts to suppress the convection and low-level convergence over the central Pacific, on the predominance of central Pacific （CP） E1 Nifio in the most recent decade. However, how interannual variabilities affect the climate mean state has been less thoroughly investigated. Using a linear shallow-water model, the ef- fect of decadal changes of air-sea interaction on the two types of El Nifio and the climate mean state over the tropical Pacific is examined. It is demonstrated that the predominance of the eastem Pacific （EP） and CP E1 Nino is dominated mainly by relationships between anomalous wind stresses and sea surface temperature （SST）. Furthermore, changes between air-sea interactions from 1980-98 to 1999-2011 prompted the generation of the La Ninalike pattern, which is similar to the background change in the most recent decade.  相似文献   

江淮流域夏季降水的准两年振荡特征及其关联因子分析          下载免费PDF全文

张璟  智协飞  缪锴  罗晓蔚 《大气科学学报》2014,37(5):541-547

利用1951—2010年我国江淮流域11个测站夏季(6—8月)降水资料和NCAR提供的北半球月平均海平面气压场资料以及相关的西太平洋副高指数资料,采用Morlet小波变换、交叉小波变换及相关分析等方法讨论了降水准两年振荡现象的年际变化规律及其与东亚夏季风、副高的关系。结果表明,准两年振荡分量在江淮地区夏季降水场的年际振荡中十分重要,且经历了由强到弱再到强的变化过程;同时降水与夏季风强度及副高脊线位置的准两年变化均存在较好的同期相关,彼此间的相互影响还体现在年际尺度上,并分别在4 a和1 a时间尺度上有明显的滞后、超前关系。  相似文献   

南海大气季节内振荡特征及其与ENSO循环的关系   总被引：3，自引：2，他引：1       下载免费PDF全文

祝丽娟  王亚非  高桥正明 《大气科学学报》2014,37(1):9-18

采用1979—2009年NCEP/NCAR再分析资料、NOAA向外长波辐射(outgoing long-wave radiation,简称OLR)及扩展重建海表面温度资料,对南海大气季节内振荡(Intra-seasonal Oscillation,简称ISO)特征及其与ENSO循环的关系进行了诊断分析。结果表明:1)南海大气ISO的30~60 d周期在5—10月均显著。一般年南海大气ISO的对流传播在纬向上存在东传和西传,在经向上具有南北半球季节性摆动的特征。以低频动能表征的南海大气ISO强度年代际变化特征明显,近31 a来趋势增强,年变化呈单峰结构,峰值在7—8月。2)南海大气ISO的对流与ENSO循环显著相关,其强度在El Nio(La Nia)年减弱(增强)。与一般年对比,南海大气ISO对流在El Nio和La Nia年均表现为西传减弱、北传显著。北传特征表现为强对流活跃带于春季(4—5月)北跳至北半球(在La Nia年最北可至35°N),但在北半球的传播方向与一般年相比存在显著差异。3)南海大气ISO强度与ENSO循环关系密切,在El Nio(La Nia)年减弱(增强),两者表现为约半年(6~8个月)的滞后相关。Nio3区海表面温度异常序列与南海大气ISO强度的相关在中西太平洋地区和El Nio成熟前的春、秋季最显著,同时相关中心伴随低频动能高值区东移。  相似文献   

南海北部冷涌及其环流特征          下载免费PDF全文

张玲  智协飞 《大气科学学报》2014,37(1):28-37

利用中国南部沿海风向、地面气温及南海北部风速的变化确定南海北部冷涌的判别标准,构建了一个冷涌发生频率指数,对南海北部冷涌的年际变化特征及其环流异常进行讨论。结果表明,南海北部冷涌频率指数能够更加全面地描述冷涌系统的特征,与全国范围的冷空气爆发关系密切。南海北部冷涌与中高纬、中低纬环流具有密切的联系,是二者共同作用的结果。当贝加尔湖以西高压脊偏强,中高纬环流经向度加大,西太平洋副热带高压强度偏弱、位置偏东时,有利于大陆上冷空气南下入海,在南海北部形成冷涌。冷涌发生时,经向Hadley环流加强,调整中纬与低纬地区的大气质量,高层向北输送的大气在科氏力作用下导致东亚副热带西风急流加强,有利于冷涌的维持和加强。  相似文献