Multiple time-scale modelling of the circulation in Torres Strait—Australia     

Frederic Saint-Cast 《Continental Shelf Research》2008

Ocean circulation influences nearly all aspects of the marine ecosystem. This study describes the water circulation patterns on time scales from hours to years across Torres Strait and adjacent gulfs and seas, including the north of the Great Barrier Reef. The tridimensional circulation model incorporated realistic atmospheric and oceanographic forcing, including winds, waves, tides, and large-scale regional circulation taken from global model outputs. Simulations covered a hindcast period of 8 years (i.e. 01/03/1997–31/12/2004), allowing the tidal, seasonal, and interannual flow characteristics to be investigated. Results indicated that the most energetic current patterns in Torres Strait were strongly dominated by the barotropic tide and its spring-neap cycle. However, longer-term flow through the strait was mainly controlled by prevailing winds. A dominant westward drift developed in summer over the southeasterly trade winds season, which then weakened and reversed in winter over the northwesterly monsoon winds season. The seasonal flow through Torres Strait was strongly connected to the circulation in the north of the Great Barrier Reef, but showed little connectivity with the coastal circulation in the Gulf of Papua. Interannual variability in Torres Strait was highest during the monsoon period, reflecting variability in wind forcing including the timing of the monsoon. The characteristics of the circulation were also discussed in relation to fine sediment transport. Turbidity level in Torres Strait is expected to peak at the end of the monsoon, while it is likely to be at a low at the end of the trade season, eventually leading to a critically low bottom light level which constitutes a severe risk of seagrass dieback.  相似文献   

渤海风驱-潮致Lagrange余流的数值模拟与季相时空变异     

李国胜  王海龙  李柏良 《地理学报(英文版)》2005,15(3):273-285

The spatial distribution and seasonal variation of the tide-induced Lagrangian Residual Circulations (LRC hereafter), wind-driven LRC, and the coupling dynamic characteristics were simulated using ECOM, given the Hellerman and Rosenstein global monthly-mean wind stresses. The results showed that the tide-induced LRC of the harmonic constituent M2 bears an identical pattern in four seasons in the Bohai Sea: the surface one is weak with random directions; however, there exist a southeast current from the Bohai Strait to the Laizhou bay, and a weakly anticlockwise gyre in the south of the Bohai Strait for the bottom layer LRC. The magnitude of bottom layer tide-induced LRC is larger than the surface one, and moreover, it contributes significantly to the whole LRC in the Bohai Sea. Unlike the identical structure of the tide-induced LRC, the wind driven LRC varies seasonally under the prevailing monsoon. It forms a distinct gyre under the summer and winter monsoons in July and January respectively, but it seems weak and non-directional in April and September.  相似文献   

0509号台风暴雨过程分析与暴雨灾害评估   总被引：2，自引：0，他引：2       下载免费PDF全文

盛永  陈艳秋  廖国进  黄阁 《气象与环境学报》2006,22(6):29-33

针对2005年8月8～10日辽宁区域性台风暴雨过程,以常规气象资料、自动站资料及卫星云图资料为基础进行分析。结果表明:暴雨是台风、副热带高压与西风槽相互作用的结果,较好的水汽条件是产生台风暴雨的重要条件之一,低空急流是水汽输送的通道,也是台风暴雨的明显特征之一;结合单站气压连续变化以及云系变化判断“麦莎”登陆时间地点;应用基于概率分析的暴雨事件快速评估模型对暴雨灾害进行评估,评估表明暴雨过程为三级暴雨灾害,属中度级别。  相似文献   

北半球环状模和东北冷涡与我国东北夏季降水关系分析   总被引：27，自引：3，他引：24       下载免费PDF全文

何金海  吴志伟  祁莉  姜爱军 《气象与环境学报》2006,22(1):1-5

利用国家气象信息中心提供的1951～2004年全国160个测站月平均降水资料和欧洲中心提供的ERA-40再分析资料,对近50多年东北地区夏季降水、东北冷涡与前期北半球环状模和海温的关系进行了统计分析,定义了一个夏季(6～8月)东北冷涡强度指数(NECVI)。结果表明:NECVI能够较好表征东北低涡的气候效应;夏季东北冷涡强度与降水存在显著的正相关,东北冷涡强年,降水偏多,前期2月北半球环状模(NAM)偏弱;东北冷涡偏弱年,降水偏少,前期2月NAM偏强。此外,夏季东北冷涡与前期的中国近海海温存在显著的负相关,前期NAM和中国近海海温的异常可以作为夏季东北冷涡异常的一个前兆信号,进而为东北地区夏季降水异常的预测提供参考依据。  相似文献   

赤道东太平洋海温与我国江淮流域夏季旱涝的成因分析   总被引：30，自引：4，他引：26       下载免费PDF全文

励申申  寿绍文 《应用气象学报》2000,11(3):331-338

对赤道东太平洋和西太平洋暖池海温与江淮流域夏季降水的关系作功率谱分析和相关分析.指出秋冬季增暖的厄尔尼诺事件对应江淮流域夏季降水偏多, 春夏季开始发展的ENSO事件江淮流域夏季降水偏少.对两种在不同季节增暖的ENSO事件对应的异常流场特征及其对江淮流域降水的影响用1991年和1994年实例作对比分析.不同季节增暖的ENSO事件在太平洋热带地区环流调整的不同阶段可能是影响夏季风活动和东亚夏季天气气候异常的主要原因.  相似文献   

对20世纪70年代中后期Walker环流异常减弱的分析   总被引：1，自引：1，他引：0  

艾丽坤 《气候与环境研究》2004,9(2):303-315

20世纪70年代中后期以后,位于达尔文岛的观测海平面气压值(SLP)不断升高,而位于塔西提岛的观测SLP不断下降,形成了在年代际尺度上最弱的热带太平洋东西向环流,即Walker环流.70年代中后期以后,在Walker环流不断减弱的同时,亚洲夏季风也在减弱.通过对海平面气压场的长期变化特征分析,我们发现20世纪70年代中期以后,副热带西太平洋(20～30°N,130～150°E)的SLP不断下降,与不断上升的热带西太平洋(10°S～0°,130～150°E) SLP形成了一个在年代际尺度上的反相关震荡型.这个负SLP距平与江淮流域的对流上升运动相对应,造成了中国地区夏季江淮流域降水增加而华北降水减少的格局.    相似文献   

Main features of regional circulation variation during onset of the south china sea monsoon in 1998   总被引：4，自引：0，他引：4  

Shao Hui  Qian Yongfu 《大气科学进展》2000,17(2):322-338

1.IntroductionTheAsiansummermonsoonconsistsoftwosystems,i.e.,theSouthAsianmonsoonandtheEastAsianmonsoon.TheSouthChinaSea(SCS)monsoonisoneoftheimportantsubsystemsoftheEastAsianmonsoon.IthaslongbeenconcernedabouttherelationshipoftheSCSmonsoonwithchangesofthegeneralcirculationandweatherpatternsinadjacentregions.TaoandChen(1987)suggestedthattheonsetoftheAsiansummermonsoonstartsfirstinthenorthernSCSusuallyinmid--May,thenpropagatesnorthwardtothemainlandofChinaandthewesternPacificsouthofJap…  相似文献   

Circulation and boundary layers in differentially heated rotating stratified fluid     

J. A. Whitehead  J. Pedlosky 《Dynamics of Atmospheres and Oceans》2000,31(1-4)

Recent laboratory experiments with rotating stratified water in a cylinder have revealed many of the predictions of linearized, analytic theory. Earlier measurements of the velocity field generated in a cylinder by top heating compared well with theory. Large stratification clearly suppressed Ekman pumping so that the interior velocity field (primarily azimuthal) responded by satisfying no-slip top and bottom boundary conditions without the need for Ekman layers. This interior flow also occupied a boundary layer of greater thickness than the Ekman layer under some conditions. Theory and experiments have now been conducted for sidewall heating. As before, experiment and theory agree well over some parameter ranges. But for some parameters, the flow is unstable. The exact nature of the instability remains poorly understood. The size of one combination of both vertical and horizontal boundary layers is governed by the Rossby radius of deformation multiplied by the square root of the Prandtl number. Sidewall boundary layers and their scales will be reviewed with the present results in mind.  相似文献   

1998年中国特大洪涝时期的环流特征   总被引：14，自引：3，他引：11  

林学椿  张素琴 《地球物理学报》2000,43(5):607-615

研究了 1 998年我国特大洪涝的环流特征 ,长江流域洪涝年全国有两种降水分布型 :即长江流域大水全国降水偏多型及长江流域大水其南北降水偏少型 .进而 ,研究了这两类分布型的环流特征 ,并指出北半球 50 0hPa位势高度场有着显著的差异 .鄂霍茨克海高压的建立是长江流域多雨的重要条件 ,南海高压的强弱在全国降水分布型中起着重要的作用  相似文献   

雅安市短时强降水天气模型及其物理指标特征          下载免费PDF全文

邱双  王俊驿  吴亚平  高文良  原桂英 《中低纬山地气象》2018,42(4):49-54

该文利用2010—2014年雅安市381个区域自动站雨量数据、Micaps实况资料以及NCEP再分析资料,选取这5 a典型的53个个例对其进行环流形势分型,结果表明:(1)影响雅安市短时强降水的环流形势主要包括:高原切变型、高空槽型、低涡型、副高控制型、两高切变型、台风外围型7类。其中切变型占所有个例的43%,对典型个例分析其高低空天气系统的配置,最后将环流形势的主要特征归纳为3大类型:高原切变型、两高切变型以及副高控制型。进一步分析其高低空配置,建立3种主要类型的天气模型。(2)利用NCEP再分析资料计算强降水发生时物理量的阈值,统计分析超过短时强降水样本60%以上的各个物理量阈值。在热力和水汽条件方面,高空切变型和两高切变型普遍比副高控制型较好;动力方面,前两种类型动力参数指示意义较好,以系统性辐合抬升为主,而第3种类型主要是受低层偏东风的扰动和地形的作用引起的局地抬升作用。  相似文献