沿岸上升流和沿岸急流的一个半解析理论   总被引：4，自引：2，他引：4       下载免费PDF全文

巢纪平  陈显尧 《地球物理学报》2003,46(1):26-30

在考虑了陆架地形后，在垂直海岸的x z剖面上 ，对Boussinesq流体的非线性海洋运动方程求得了总动量守恒、温度守恒和位势涡度守恒的 普 适形式，进而得到流函数所满足的椭圆型二阶偏微分方程，在给定流体沿地形运动的条件下 ，算出问题的解. 计算结果表明，沿岸可以出现上升流也可以出现下沉流，它依赖于海洋的 大尺度背景条件. 计算所得的上升流、沿岸急流、温度的锋区结构与一些观测事实接近.  相似文献   

一次台风暴雨的初步分析   总被引：17，自引：4，他引：17       下载免费PDF全文

黄文根邓北胜  熊廷南 《应用气象学报》1997,8(2):247-251

文章对1994年7月12～13日一次登陆台风造成的华北暴雨作了天气动力学诊断分析。分析表明，9406号台风登陆后，台风和太平洋副热带高压间形成的偏东南风低空急流，具有明显超地转特征，它是触发这次台风暴雨的关键系统。Q矢量诊断表明，Q矢量辐合区与暴雨位置较为一致。  相似文献   

ANALYSIS OF COMPOSITE DIAGNOSIS OF OCEANIC EXPLOSIVE CYCLONES^*          下载免费PDF全文

WANG Jinsong  DING Zhiying  ZHAI Zhaofeng 《Acta Meteorologica Sinica》2004,18(3):327-346

Using the data of ECMWF (European Center for Medium-range Weather Forecasts) to undertake composite diagnoses of 16 explosive cyclones occurring at the Atlantic and the Pacific Oceans,it is found that there are a lot of obvious discrepancies on the basic fields between these strong and weak explosive cyclones.The major reasons why the explosive cyclones over the Atlantic are stronger than those over the Pacific Ocean are that the non-zonal upper jet and the low-level warm moist flow over the Atlantic are stronger.The non-zonal upper jet offers stronger divergence,baroclinicity and baroclinic instability fields for explosive cyclones.Anticyclonic curvature at the high level of strong explosive cyclones is easy to make the inertia-gravitational wave developing at the moment of northward transfer of energy and stimulate the cyclones deepening quickly.Warm advection and diabatic heating can cause the upper isobaric surface lifting,as a result,the anticyclone curvature of cyclones enlarges,and wave energy develops easily as well.The most powerful period of the development of explosive cyclones is just the time when the positive vorticity advection center is located over the low vortex.At the upper level,when the distribution of potential vorticity contours changes suddenly from rareness to denseness,and the large values of the potential vorticity both in the west and north sides of cyclones extend downwards together,then cyclones are easy to explosively develop.The formation of strong explosive cyclones is closely related with the non-zonality of upper jet and the anticyclonic curvature.  相似文献   

低空急流与阿勒泰暖区大--暴雪   总被引：2，自引：0，他引：2  

晋绿生  赵俊荣 《沙漠与绿洲气象(新疆气象)》2004,27(2):13-15

分析了冬季产生新疆低空急流的大型环流特征及低空急流与阿勒泰暖区大-暴雪的关系。结果表明，在中高纬度欧亚范围内呈现“双阻型”，中亚中纬度高空维持纬向强急流锋区的情况下，若有巴尔喀什湖以南的暖湿气流向北输送，则有利于造成阿勒泰暖区大-暴雪的新疆低空急流产生。高低空急流的位置及强度可作为降雪量和大-暴雪落区的短期预报指标。  相似文献   

用VOF方法模拟静止浅水环境中的垂向紊动射流   总被引：2，自引：0，他引：2       下载免费PDF全文

袁丽蓉  沈永明  郑永红 《水科学进展》2004,15(5):566-570

以k-ε紊流模型为基础,针对浅水环境垂向射流的水面会有明显突起情况,采用VOF(Volume of Fluid)方法追踪自由面,建立了适合浅水环境垂向平面紊动射流的二维数学模型.对不同入射速度、水深、入射口宽度组合进行了大量的数值模拟实验,对整个流场的分布作了分析,发现自由面的分布特点和速度矢量场的分布特点相对应;中轴线附近的自由面隆起具有自相似性,文中给出了拟合表达式;由于水面的阻滞,中轴线上垂向速度的衰减较自由射流快,衰减规律随水深和射流宽度而异.  相似文献   

2003年广西最大一次锋面暴雨天气过程特征分析     

农孟松  卢伟萍  刘国忠 《云南地理环境研究》2004,(Z1)

本文利用常规观测资料和物理量资料,对2003年6月26～28日广西全区性范围暴雨天气过程进行诊断分析,指出副热带高压逐渐加强西伸与弱冷空气在广西维持对峙是暴雨产生的主要原因;物理量和云图分析表明,暴雨发生前广西上空有深厚的不稳定层结存在,造成本次的强降水是对流层中低层暖湿空气被地面弱冷空气抬升的结果。  相似文献   

Seasonal Variation of the East Asian Subtropical Westerly Jet and Its Association with the Heating Field over East Asia   总被引：3，自引：0，他引：3  

KUANG Xueyuan  ZHANG Yaocun 《大气科学进展》2005,22(6):831-840

The structure and seasonal variation of the East Asian Subtropical Westerly Jet （EAWJ） and associations with heating fields over East Asia are examined by using NCEP/NCAR reanalysis data. Obvious differences exist in the westerly jet intensity and location in different regions and seasons due to the ocean-land distribution and seasonal thermal contrast, as well as the dynamic and thermodynamic impacts of the Tibetan Plateau. In winter, the EAWJ center is situated over the western Pacific Ocean and the intensity is reduced gradually from east to west over the East Asian region. In summer, the EAWJ center is located over the north of the Tibetan Plateau and the jet intensity is reduced evidently compared with that in winter. The EAWJ seasonal evolution is characterized by the obvious longitudinal inconsistency of the northward migration and in-phase southward retreat of the EAWJ axis. A good correspondence between the seasonal variations of EAWJ and the meridional differences of air temperature （MDT） in the mid-upper troposphere demonstrates that the MDT is the basic reason for the seasonal variation of EAWJ. Correlation analyses indicate that the Kuroshio Current region to the south of Japan and the Tibetan Plateau are the key areas for the variations of the EAWJ intensities in winter and in summer, respectively. The strong sensible and latent heating in the Kuroshio Current region is closely related to the intensification of EAWJ in winter. In summer, strong sensible heating in the Tibetan Plateau corresponds to the EAWJ strengthening and southward shift, while the weak sensible heating in the Tibetan Plateau is consistent with the EAWJ weakening and northward migration.  相似文献   

The coupling instability of Rossby and topographic Rossby waves in the equatorial area     

CHAO Jiping    LIU Lin  & YU Weidong . Laboratory of Marine Science  Numerical Modeling  State Oceanic Administration  Qingdao  China  . National Research Center for Marine Environmental Forecasts  State Oceanic Administration  Beijing  China  . Ocean University of China  Qingdao  China 《中国科学D辑(英文版)》2005,48(10)

Before the 1980s, El Ni?o was believed as the sea surface warming along the coast of Peru in South America. As the positive anomaly strengths, the warm water expands westward along the equator to form large area of anomalous high sea surface temperature. Rasmusson and Carpenter (1982) summarized the de-velopment process of the sea surface warm water and the corresponding wind field[1] during ENSO cylce. However, this canonical El Ni?o was questioned by 1982-1983 warm episode and later dat…  相似文献   

中国东部高空颠簸时空分布特征及其与热带中东太平洋海温的关系   总被引：1，自引：0，他引：1  

阿利曼  王君  冯锦明  李秀连 《大气科学》2016,40(5):1073-1088

本文利用1979～2014年NCEP-DOE日平均再分析资料和中国区域2375份航空器空中颠簸报告资料,研究中国东部区域高空颠簸的时空分布特征及其与热带中东太平洋海温异常（简称“海温异常”;空间范围:5°S～5°N,120°～170°W）的关系以及产生这种关系的可能原因。结果表明:中国东部地区高空颠簸与东亚副热带西风急流之间存在显著时空相关关系,其原因是高空纬向风引起的垂直风切变是构成高空颠簸时空分布的主导因素。中国东部夏季高空颠簸与海温异常存在正相关关系;冬季呈现南北两个正负相关区:以30°N为界,北部区域存在显著的负相关,南部区存在显著的正相关,在30°N急流轴附近区域无显著相关关系。海温异常影响中国高空颠簸时空分布的可能原因是海温变化引起对流层高层温度出现异常,进而影响温度的经向梯度,导致东亚副热带西风急流强度和位置出现异常（夏季,急流轴南侧出现西风异常;冬季,急流轴北侧出现东风异常,南侧出现西风异常）。高空纬向风的变化导致纬向风的垂直梯度和经向梯度出现异常,最终影响高空颠簸的时空分布特征。对流层高层温度的异常变化可能是由与热带海温异常相关的平流层水汽变化所引起。  相似文献   

冬季东亚高空副热带急流和温带急流协同变化与中国南方地区降水的关系     

聂锋  廖治杰  徐勇 《气象科学》2016,36(1):20-27

利用NCEP/NCAR再分析数据和中国台站降水资料研究冬季东亚高空副热带急流和温带急流协同变化特征及其与中国南方地区降水的关系,发现冬季东亚高原急流与温带急流同期反向协同变化特征最为显著。即高原急流增强,同时温带急流减弱(SW型)和高原急流减弱,同时温带急流增强(WS型)。当高原急流增强(减弱)而温带急流减弱(增强)时,中国南方地区降水显著增加(减少)。合成分析表明,不同急流协同变化型态下冷暖空气活动特征存在较大差异,高原急流与温带急流的反向协同变化可以真实反映与冬季中国南方地区降水相关联的冷暖空气活动特征,进而导致不同降水形态的产生。  相似文献