夏季热带北大西洋海温异常对西北太平洋热带气旋生成的影响          下载免费PDF全文

霍利微  郭品文  张福颖 《大气科学学报》2016,39(1):55-63

利用1979—2012年西北太平洋热带气旋最佳路径资料,Hadley中心的海温资料和NCEP/NCAR再分析资料等,研究了夏季(6—10月)热带北大西洋海温异常与西北太平洋热带气旋(Tropical Cyclone,TC)生成的关系及其可能机制。结果表明,夏季热带北大西洋海温异常与同期西北太平洋TC生成频次之间存在显著的负相关关系。热带北大西洋海温的异常增暖可产生一对东—西向分布的偶极型低层异常环流,其中气旋性异常环流位于北大西洋/东太平洋地区,反气旋异常环流位于西北太平洋地区。该反气旋环流异常使得TC主要生成区的对流活动受到抑制、低层涡度正异常、中低层相对湿度负异常、中层下沉气流异常,这些动力/热力条件均不利于TC生成。此外,西北太平洋地区低层涡旋动能负异常,同时来自大尺度环流的涡旋动能的正压转换也受到抑制,不能为TC的生成和发展提供额外能量源。反之亦然。  相似文献   

2007年夏季江淮强降水过程中10~30d低频变化及其与对流层上层波包活动的联系          下载免费PDF全文

陈丹萍  管兆勇  侯俊  奚子惠 《大气科学学报》2016,39(2):177-188

利用NCEP/NCAR再分析和全国740站逐日降水资料,运用一点滞后相关等方法,对2007年夏季江淮流域强降水期间低频振荡的波动活动特征及其与降水低频变化的联系进行了分析。结果表明,在2007年夏季降水中,降水低频分量起着重要作用。降水的低频振荡主周期为10~30d,降水距平时间序列与10~30d低频分量具有较好的对应关系。低频扰动在对流层上层和低层都呈现波列状分布,且在降水活跃位相时,低频环流在高、低层具有斜压结构。在对流层上层,低频扰动有缓慢的东移倾向,相速度为每天2~3个经度。西风带中存在多次移动性波列向下游的传播,且在120°E以西以每天14经度的群速度向下游频散能量,表明10~30d低频波动具有明显的下游发展特征。在强降水开始5d前,低频波动与能量可起源于高纬的乌拉尔山附近,沿着西北-东南向的路径向下游传播。下游发展的低频波动为江淮流域带来了能量,为强降水的发生提供了条件。这些结果加深了人们对低频波动在江淮流域强降水过程中所起作用的认识,可为寻找江淮流域强降水过程预报线索提供科学依据。  相似文献   

Population genetic diversity and structure of a dominant tropical seagrass,Cymodocea rotundata,in the Western Pacific region          下载免费PDF全文

Dan M. Arriesgado  Hiroyuki Kurokochi  Yuichi Nakajima  Yu Matsuki  Wilfredo H. Uy  Miguel D. Fortes  Wilfredo L. Campos  Kazuo Nadaoka  Chunlan Lian 《Marine Ecology》2016,37(4):786-800

Cymodocea rotundata is an ecologically important tropical pioneer seagrass species distributed in the Indo‐Pacific region. The population genetic diversity and structure of this species were analysed at 46 sites spanning the Philippines, Ryukyu Islands (northern limit) and Hainan Island, by using microsatellite simple sequence repeat (SSR) markers. Analyses revealed the persistence of C. rotundata likely relies on local population dynamics and fitness influenced by environmental gradients, with sexual reproduction prevalent in the Philippines while the Ryukyu and Hainan populations were predominantly established by clonal spread. Analysis of molecular variance showed significant genetic differentiation (P < 0.001) among three geographic regions: the Philippines, Ryukyu and Hainan. Furthermore, the mean fixation index value was very high (F_ST = 0.36), indicating poor dispersal potential or limited gene flow. Allelic richness and heterozygosity of C. rotundata was comparable in the Philippines and Ryukyu Islands populations. More private alleles were found in the Philippines and excess heterozygotes in the Ryukyu Islands. STRUCTURE analysis revealed that the Ryukyu and Hainan populations were mosaics of admixed alleles of individuals from the Philippines. An assignment test suggested that recruitment occurs from the Northeast Philippines to Ryukyu Islands. These results suggest that the Philippine populations are tropical seagrass hotspots and perhaps the origin of the populations in the Ryukyu and Hainan Islands. This scenario is most likely driven by the Kuroshio Current and island integration events during plate tectonic activities. The Philippine Archipelago is considered of high importance for conservation objectives and management plan of seagrasses. Likewise, the Ryukyu Islands are also important in terms of conserving regional diversity because locally adapted genotypes have important evolutionary potential in the face of environmental change.  相似文献   

中国近海以及邻近海域海洋再分析产品(CORA)中季节内变化的评估   总被引：5，自引：2，他引：3  

张敏  周磊  付红丽  姜良红  章向明 《海洋学报(英文版)》2016,35(3):90-101

A regional reanalysis product—China Ocean Reanalysis(CORA)—has been developed for the China's seas and the adjacent areas. In this study, the intraseasonal variabilities(ISVs) in CORA are assessed by comparing with observations and two other reanalysis products(ECCO2 and SODA). CORA shows a better performance in capturing the intraseasonal sea surface temperatures(SSTs) and the intraseasonal sea surface heights(SSHs) than ECCO2 and SODA do, probably due to its high resolution, stronger response to the intraseasonal forcing in the atmosphere(especially the Madden-Julian Oscillation), and more available regional data for assimilation. But at the subsurface, the ISVs in CORA are likely to be weaker than reality, which is probably attributed to rare observational data for assimilation and weak diapycnal eddy diffusivity in the CORA model. According to the comparison results, CORA is a good choice for the study related to variabilities at the surface, but cares have to be taken for the study focusing on the subsurface processes.  相似文献   

海洋上层暖水在热带气旋迅速增强中的作用:基于台风威马逊(1409)的个例研究   总被引：5，自引：1，他引：4  

孙佳  左军成  凌征  闫运伟 《海洋学报(英文版)》2016,35(3):63-68

在登陆海南岛之前,台风威马逊在南海北部从热带风暴级别迅速增强成为超强台风。观测数据的分析结果显示,海洋上层的异常暖水在威马逊的迅速增强过程中扮演了重要的角色。威马逊期间,南海北部的海表面温度相比于气候态海表面温度暖很多。这部分异常暖水为威马逊提供了更多的能量,从而导致了威马逊的迅速增强。数值模拟结果进一步证明,南海北部的暖水在台风威马逊的迅速增强过程中起重要作用。如果没有这团异常暖水的影响,威马逊只增强25 hPa,仅为有暖水影响条件下增强程度的58.1%。  相似文献   

北大西洋大青鲨渔业生物学初步研究     

高春霞  戴小杰  田思泉  吴峰 《海洋科学》2016,40(10):55-62

大青鲨(Prionace glauca)是金枪鱼延绳钓渔业中最主要的兼捕鱼种之一,作为海洋生物链的顶端物种对海洋生态系统的稳定性和多样性起到了重要作用。作者根据中国金枪鱼渔业科学观察员在北大西洋海域(3°~55°N,15°~40°W)采集的2 112尾大青鲨数据,按不同性别对其渔业生物学特征进行初步研究。结果表明:雌、雄大青鲨的优势叉长组分别为180~220 cm、190~230 cm,雄性叉长均值显著大于雌性,雌、雄性比符合1︰1;大青鲨叉长-全长、尾凹长-全长的线性关系分别为L_F=0.8008L_T+7.3361,L_P=0.7576L_T–1.8479;北大西洋热带海域(3°~13°N)兼捕的大青鲨群体组成以大个体为主(180~240 cm),冰岛附近海域(48°~51°N)兼捕的大青鲨群体组成以小个体为主(100~210 cm);大青鲨叉长和质量关系式为W_R=7×10~(–6)L_F~(2.9994);大青鲨肝脏为性腺的发育提供能量,成熟个体的肝质量指数显著小于未成熟个体;热带海域兼捕的大青鲨以性成熟个体为主(96.9%),冰岛海域兼捕的大青鲨以未成熟个体居多(77.1%);50%雌性性成熟个体对应的叉长为178.7 cm,50%雄性性成熟个体对应叉长为173.6 cm;雌性怀仔大青鲨的叉长与其怀仔数量线性关系为L_S=0.419×L_F–49.7(R~2=0.3905),幼仔雌雄性比符合1︰1;胃含物中以沙丁鱼和鱿鱼出现频率最高。作者的研究有助于更好地了解北大西洋大青鲨的生物学特征,为区域性渔业管理组织评估大青鲨种群资源状态提供数据参考。  相似文献   

Hybrid N-order Lagrangian Interpolation Eulerian?Lagrangian Method for Salinity Calculation     

吴炎成  朱首贤  周林  游小宝  张文静 《海洋工程》2016,(2):283-295

The Eulerian?Lagrangian method (ELM) has been used by many ocean models as the solution of the advection equation, but the numerical error caused by interpolation imposes restriction on its accuracy. In the present study, hybrid N-order Lagrangian interpolation ELM (LiELM) is put forward in which the N-order Lagrangian interpolation is used at first, then the lower order Lagrangian interpolation is applied in the points where the interpolation results are abnormally higher or lower. The calculation results of a step-shaped salinity advection model are analyzed, which show that higher order (N=3?8) LiELM can reduce the mean numerical error of salinity calculation, but the numerical oscillation error is still significant. Even number order LiELM makes larger numerical oscillation error than its adjacent odd number order LiELM. Hybrid N-order LiELM can remove numerical oscillation, and it significantly reduces the mean numerical error when N is even and the current is in fixed direction, while it makes less effect on mean numerical error when N is odd or the current direction changes periodically. Hybrid odd number order LiELM makes less mean numerical error than its adjacent even number order LiELM when the current is in the fixed direction, while the mean numerical error decreases as N increases when the current direction changes periodically, so odd number of N may be better for application. Among various types of Hybrid N-order LiELM, the scheme reducing N-order directly to 1st-order may be the optimal for synthetic selection of accuracy and computational efficiency.  相似文献   

西太平洋暖池研究综述   总被引：2，自引：0，他引：2  

胡石建  ①胡敦欣 《海洋科学集刊》2016,51(51):37-48

西太平洋暖池（Western Pacific Warm Pool）是全球海温最高的海域,汇聚了巨大的热能,在地球气候系统中具有非常重要的作用。本文综述了近30年来有关西太平洋暖池的研究进展,包括西太平洋暖池的维持机制、在不同时间尺度西太平洋暖池的变异特征和物理机制,以及西太平洋暖池的观测和数值模拟等领域的研究进展。西太平洋暖池的维持是现有地形下大气过程和海洋过程相互作用导致的,在季节内到世纪尺度均存在很强的变化。其中：季节内变化的驱动机制主要包括与大气季节内振荡(Madden Julian Oscillation)相关的对流和海表面热通量变化,以及海洋波动等海洋动力过程;季节变化主要是太阳辐射的季节变化导致;在年际尺度上,西太平洋暖池作为El Ni?o-Southern Oscillation的一部分而振荡具有显著年际变化;太平洋代际振荡（Pacific Decadal Oscillation）和大西洋代际振荡（Atlantic Multi-decadal Oscillation）驱动着西太平洋暖池的年代际变化;世纪尺度的变化显示全球变暖背景下西太平洋暖池存在扩张趋势。人类对西太平洋暖池的系统观测始于海洋观测卫星的使用,随后历经WCRP/TOGA、TAO/TRITON、TOGA-COARE、WOCE、Argo、SPICE、NPOCE等多个观测计划,极大促进了西太平洋暖池的研究。但截止到第五次耦合模式比对计划（Coupled Model Intercomparison Project 5）,多数气候模式仍未能克服热带模拟偏差,对西太平洋暖池的模拟效果较差,表明在西太平洋暖池动力学的理解和模拟方面仍有较大进步空间。  相似文献   

Intraseasonal oscillation of the rainfall variability over Rwanda and evaluation of its subseasonal forecasting skill          下载免费PDF全文

Xuan Zhou  Lin Chen  Janet Umuhoza  Yifeng Cheng  Lu Wang  Ran Wang 《大气和海洋科学快报》2021,14(6):60-65

非洲中东部地区的经济主要依靠自给农业支撑,该地区农业经济对降水的变化尤为敏感.本文以卢旺达为例,观测分析指出卢旺达的次季节降雨主要集中在10-25天;根据次季节尺度降水变率的单点相关方法,发现卢旺达的次季节降水变率和周围区域变化一致;进一步合成结果显示该地区次季节降水变率与异常西风有关,这可追溯到赤道地区西传的赤道Rossby波.最后,本文评估了当前动力模式ECMWF对 卢旺达地区(即非洲中东部)次季节降水变率的预报能力,发现EC模式在对该区域降水和相关风场指数的预报技巧都在18天左右,且预报技巧表现出一定的年际差异,这可能与热带太平洋的背景海温信号有关.该工作增进了当 前对非洲中东部地区的次季节降水变率和预测水平的认知,并且对该地区国家粮食安全和防灾减灾具有启示性意义.  相似文献   

Intraseasonal oscillation of the southwest monsoon over Sri Lanka and evaluation of its subseasonal forecast skill          下载免费PDF全文

L.A.D.Buddika Bandurathna  Lu Wang  Xuan Zhou  Yifeng Cheng  Lin Chen 《大气和海洋科学快报》2021,14(6):7-13

斯里兰卡的雨季发生于5-9月间,主要受西南季风的控制.本文发现该地区的西南季风降水存在很强的次季节变率,主导周期为10-35天.降水的季节内变化与西传的异常气旋有关.进一步,利用S2S比较计划中欧洲中心的数值预报模式(ECMWF)提供的回报试验数据,评估了当今动力模式对斯里兰卡西南季风次季节变化的预报技巧.结果显示,对季风指数的预测技巧超过30天,而对降水指数的预测技巧大约两周,且模式的预报技巧具有明显的年际差异.分析表明,能否正确模拟出大尺度环流对热带对流的响应是影响斯里兰卡降水预测的重要因子.  相似文献