共查询到20条相似文献，搜索用时 31 毫秒
1.
浙江热带气旋登陆前移动速度变化分析 总被引：1，自引：1，他引：0
利用1949~2004年登陆浙江的35个热带气旋的资料,计算了热带气旋登陆前24h和6h的速度和移速变率。结果表明,登陆浙江的热带气旋60%在登陆前移速加快,28.6%移速基本不变,11.4%移速减慢。从热带气旋登陆前的形势场、引导气流及它的结构和强度变化等方面进行分析,发现500hPa形势场的调整和引导气流的大小对热带气旋移速的变化起主导作用;热带气旋主流入通道的变化、热带气旋之间的互旋等与其移速变化有关。登陆前,热带气旋移速与其强度有一定的关系。 相似文献
2.
影响台风移动因子的数值研究 总被引：1，自引：1，他引：0
本文采用有辐散的正压原始方程模式对影响台风涡旋移动的因子进行了数值试验,试验结果表明:(1)在无环境风条件下,台风涡旋向西北方向移动,移速与台风切向风速、台风半径和台风区f场的特征有关,台风外区(指最大风速半径以外台风区域)切向风速越大、台风半径越大,台风涡旋移速向北分量越大。(2)均一环境风场中,台风移动受基本气流的平流、β效应和指向引导气流左侧的横向加速度的作用,其中基本气流的引导作用是主要的。台风移速与引导气流速度比在东风气流中要大于西风气流中,而台风移向与基本气流之间的偏角在西风气流中要大于在东风气流中。(3)台风涡旋有沿基本气流绝对涡度梯度方向的次级运动分量。(4)台风涡旋在有切变的西风气流中比在均一西风气流中易发展加强,而它的移动更偏向引导气流的左侧。 相似文献
3.
Cluster analysis of post-landfall tracks of landfalling tropical cyclones over China 总被引：1，自引：0，他引：1
In this paper, we apply finite-mixture-model-based clustering algorithms to cluster post-landfall tracks of tropical cyclones (TCs) making landfall over China. Because existing studies find that landfall surfaces or elevations affect post-landfall TC movements, we also take account of elevations in addition to time orders in this model. Our study reveals three clusters, with cluster 1 making landfall in Hainan province and moving across the western coast of Guangdong province. Most of the TC tracks in cluster 1 move over the ocean and make secondary landfalls over Yunnan province of China and Vietnam. Cluster 1 finally dissipates inland and moves westward as a result of the westward-shift subtropical high, westward steering flow, easterly vertical wind shear and strong mountainous blocking. Cluster 2 makes landfall over Guangdong and Fujian provinces. TCs in cluster 2 subsequently move inland and disappear due largely to westward-shift subtropical high, easterly steering flow, easterly vertical wind shear and relatively strong mountainous blocking. Cluster 3 makes landfall along the Fujian and Zhejiang coast and sustains a long period of time, recurving mostly to the mid-latitude region owing to the surrounding eastward-shift subtropical high, westerly vertical wind shear, weak mountainous blocking and westerly steering flow. Because cluster 2 is significantly associated with La Niña events, TCs more likely make landfall over southeastern China coast and move westward or northwestward without recurving. Cluster 3 sustains a longer time than clusters 1 and 2 in spite of its weak horizontal and vertical water vapor supply. TCs in cluster 3 interact actively with westerlies during the post-landfall period. However, we cannot observe any analogous interactions with the mid-latitude westerlies in clusters 1 and 2. TCs of clusters 1 and 2 are influenced by summer monsoon flows. Moreover, summer monsoon exerts a greater influence on cluster 1 than cluster 2. The composite 200 hPa divergence of cluster 3 is stronger than that of clusters 1 and 2. This explains to some degree why cluster 3 sustains longer than clusters 1 and 2 after making landfall. 相似文献
4.
Mark R. Jury 《Theoretical and Applied Climatology》2011,106(1-2):117-126
This observational study considers Caribbean cyclogenesis in the period 2003?C2009. Numerous events are identified from maximum of low-level relative vorticity and rain rate, and a case study is analyzed. Although fast moving tropical cyclones (TC) pose dangers to Caribbean Islands, it is the slower moving TC that inflict flood damage. The Atlantic warm pool enlarges through October as steering winds slacken. African easterly waves move over the warm pool and draw moist unstable air, while near-equatorial Kelvin waves from the Pacific surge into the Caribbean. The westerly flow accelerates around the northern Andes and is drawn into TC Omar 13?C15 October 2008. A combination of warm pool air and cyclonic vorticity provided by transient zonal waves sets off the process of cyclogenesis. 相似文献
5.
通过求取定常线性准地转位涡模式的数值解,研究了感热型垂直非均匀分布的冷、热源强迫所激发的副热带环流的结构特征,讨论了副热带背景风场和洋面辐射冷却对洋面副热带高压“三角形偏心”结构形成的重要作用。结果表明,基本流对感热加热强迫的副热带环流有重要影响,当基本流为常数时,感热加热强迫的气旋和反气旋主要集中在对流层中下层,且地面系统远强于中高层。当基本流为非常数时,其经向切变能改变气旋和反气旋中心的经向位置,使它移至0风速所在纬度附近;其垂直变化加强了中高层气旋和反气旋,中心位于对流层上层,与南亚高压的位置基本一致。研究结果还表明,在大洋东部洋面辐射冷却与副热带地区背景风场的共同作用下,形成了洋面副热带高压特有的“三角形偏心”结构。副热带高纬度的西风使感热强迫的洋面副热带高压东移,低纬度的东风使其西移,形成东北—西南走向的“平行四边形”结构,且中心位于大洋西部。大洋东部强洋面辐射冷却激发的洋面反气旋加强了大洋东部的副热带高压,使其中心东移至大洋东部,从而表现出东北—西南走向的“三角形偏心”结构。 相似文献
6.
利用中国气象局(CMA)提供的热带气旋最佳路径资料和欧洲中心(ECMWF)提供的ERA interim再分析资料,对2018年两个北上影响山东的台风"摩羯"和"温比亚"路径差异的原因进行分析发现:"摩羯"和"温比亚"台风路径的差异主要与周围天气系统分布差异有关,两台风均先后受到副热带高压和大陆高压的影响,"温比亚"还受高空槽的影响,使其转向角度较大,而台风与高压系统相互作用形成的引导气流是影响这两个台风路径的主要因素。"摩羯"和"温比亚"的最佳引导气流均位于台风中心5个纬度半径内,不同阶段所受引导气流的高度存在差异,台风登陆前中低层引导气流对台风移向的指示作用均优于高层,登陆后转向前纬向引导气流均优于经向,但稳定性稍差,转向后除"温比亚"经向引导气流相关较差外均整层相关较好,中高层略优于低层,且高层风(300～200hPa)可以提前12h预报台风转向。此外,台风总是向着台风附近的正涡度平流方向移动,正涡度平流越强,台风移动越快。 相似文献
7.
Sanjeev Kumar Singh C. M. Kishtawal Neeru Jaiswal Randhir Singh P. K. Pal 《Meteorology and Atmospheric Physics》2012,117(3-4):103-120
In the present study, a new approach is discussed to find out the residual steering flow from the high-resolution global Numerical Weather Prediction (NWP) model-forecasted wind fields, which have been used in the Lagrangian advection model to determine the track of tropical cyclones formed in the Indian Ocean. The Lagrangian advection model is newly developed model and conceptually closer to the dynamical models, which utilizes environmental steering flow and the effect due to earth’s rotation (the beta-effect) to determine the motion of cyclone. In this approach, the effect of environmental flow on the cyclone track is examined by removing the existing cyclone vortex from the steering flow which is determined by potential vorticity approach. A new approach based on vortex pattern matching has been used to identify the cyclone vortex and to remove it from the steering flow. The tracks of five tropical cyclones (viz., Nargis, Khai_Muk, Nisha, Aila and Phyan) which were formed in the North Indian basin during the period 2008–2009 have been generated by the Lagrangian advection model using the proposed scheme. The position errors were computed with respect to the Joint Typhoon Warning Center (JTWC) best track analysis positions and compared with that of without-vortex-removal scheme. The results show that the mean track errors for five cyclones are reduced by 6–35?% for 12–72?h forecast in case of vortex-removal scheme as compared to the without-vortex-removal scheme. 相似文献
8.
环境地转基本气流的计算及热带气旋运动与其偏差的统计分析 总被引：1，自引：0，他引：1
利用国家气象中心T63L16的1.875×1.875经纬网格点资料和中央气象台编号的热带气旋实时中心位置资料,计算了1996年全年25个热带气旋,共126个时次的环境地转基本气流,分析了环境地转基本气流的垂直分布特征,并对热带气旋的实际运动与环境地转引导气流的偏差(后文将称其为引导偏差,即热带气旋的实际中心位置与按引导气流推算出的位置之间的偏差)进行了分析,发现引导气流的计算区域不同,其引导偏差是不一样的。得到了引导气流的最佳计算区域,并且发现热带气旋运动与环境地转基本气流的垂直切变结构的关系以及引导偏差与引导气流的速度、气旋本身的初始纬度位置和强度等有关。结果还表明,200～1000 hPa的深层加权平均的基本气流的引导效果最佳,可作为最佳引导气流使用。了解这些规律和特征,对热带气旋运动预报具有一定的参考意义。 相似文献
9.
10.
利用国家气象局和上海台风研究所(CMA-STI)整编的西北太平洋1970—2009年热带气旋(TC,Tropical Cyclone)及TC最佳路径数据集和2005—2010年的TC路径预报误差资料,应用百分位法,确定TC移动速度异常指标,分析了40 a来西北太平洋TC移动速度及其变化异常发生的时空分布特征,研究了TC速度预报误差对路径预报误差的影响及其与大尺度引导气流之间的关系。结果显示:1)西北太平洋TC移速及移速变化累积概率达95%(5%)分位数的阈值分别为10.8 m·s~(-1)(1.43 m·s~(-1))和2.42m·s~(-1)(-1.72 m·s~(-1))。2)快速移动及加速的TC大都出现在日本海地区,而缓慢的和减速移动TC主要出现在南海区域。3)TC移动速度异常的季节变化表现为,快速移动的TC在5月出现的频率达到最高,缓慢移动的TC在10月频率达到最高,加速移动的TC在6月频率达到最高。4)近6 a的TC移速预报误差对TC路径预报误差的贡献平均约为41.6%。5)对TC路径预报误差偏大,且移速预报误差贡献大的个例分析显示,该个例大尺度环境引导气流偏弱使TC移动速度偏慢。而如果预报的大尺度环境引导气流偏强,使预报的TC移速偏快,那么就容易导致大的路径预报误差。 相似文献
11.
从北大西洋中高纬度进入北极的极端气旋会引起北极异常增暖,与中高纬度极端天气事件关系密切,危害极大。利用ERA-Interim再分析资料和中国地面气象站观测资料,探讨了2015年1—2月两个极端气旋（C1,C2）影响中国天气的物理过程和机制。结果表明:当极端气旋生成并北移,附近大气低层和高层均出现异常增暖,中高纬度大气环流表现为乌拉尔阻塞形势形成,极涡断裂,低压槽加深南压,我国发生寒潮天气;且极端气旋伴随的异常增暖加强Rossby波能量频散,使中高纬度的槽和脊发展。对比发现,C1和C2的生成地和路径均存在差异,相比于C2,C1生成纬度较高且路径偏东,对应低温寒潮天气范围更大,但强度比C2略弱。这些结果均表明,极端气旋的生成和移动是中国寒潮天气发生的重要原因之一。 相似文献
12.
双热带气旋相互作用的研究 总被引：7，自引：1，他引：6
采用无基本气流的无辐散正压模式模拟了双热带气旋的运动。应用非对称理论研究了双热带气旋的相互作用。双热带气旋中的每个热带气旋主要由通过其中心的非对称气流（即通风气流）作用而移动。这股非对称气流是由其自身的线性和非线性效应产生的非对称涡旋与其配对热带气旋形成的非对称涡旋相叠加而引起的。 相似文献
13.
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
14.
高原低涡移出高原的观测事实分析 总被引：27，自引：0，他引：27
应用天气学、统计学原理,结合TRMM资料,分析了1998—2004年5—9月移出高原的低涡的活动特征。结果指出:6—8月是高原低涡移出高原影响中国东部天气的主要时段,它与高原低涡在高原上的活动特征及西南低涡移出高原特征均不同;移出高原的高原低涡的涡源主要在曲麻莱附近、德格附近,这与高原上产生低涡的涡源不同;移出高原的高原低涡的移动路径多数是随低槽的活动而向东、向东南移动,这与高原低涡在高原上多数是沿切变线移向东北不同,高原低涡移出高原后,不仅影响中国的范围广,还可能影响到朝鲜半岛、日本;高原低涡移出高原后涡的强度、性质会有变化,在高原以东活动时间长(≥36 h)的高原低涡,移出高原前多数为暖性低涡,移出高原后多数为斜压性低涡,低涡加强、多数可产生暴雨、大暴雨;高原低涡移出高原后移到海洋上,往往因下垫面不同而变化,出海后都有降水加强、多数位势高度下降的现象;移出高原后的高原低涡因东面海上热带气旋活动而少动,与其南面热带气旋活动相向而行,因季风低压少动而少动的现象。 相似文献
15.
Based on a barotropic vortex model, generalized energy-conserving equation was derived and two
necessary conditions of basic flow destabilization are gained. These conditions correspond to generalized
barotropic instability and super speed instability. They are instabilities of vortex and gravity inertial wave
respectively. In order to relate to practical situation, a barotropic vortex was analyzed, the basic flow of which is similar to lower level basic wind field of tropical cyclones and the maximum wind radius of which is 500 km.
The results show that generalized barotropic instability depending upon the radial gradient of relative vorticity
can appear in this vortex. It can be concluded that unstable vortex Rossby wave may appear in barotropic vortex. 相似文献
16.
17.
登陆热带气旋长久维持与迅速消亡的大尺度环流特征 总被引：61，自引：9，他引：61
采用动态合成分析方法 ,对登陆后长久维持热带气旋 (LTC)和迅速消亡热带气旋 (STC)的大尺度环流特征进行合成分析和动力诊断。研究表明 :(1)LTC登陆后 ,在一个长波槽前有向偏北移动靠近中纬度斜压锋区的趋势 ,而STC登陆后 ,无长波槽靠近 ,并远离中纬度斜压锋区 ;(2 )LTC登陆后 ,仍与一支低空急流水汽输送通道连结 ,而STC登陆后很快与这支水汽通道分离 ;(3)LTC登陆后逐渐变性 ,获取斜压能量 ,其环境风垂直切变增强 ,Δζ2 0 0 -850负值增大 ,而STC登陆后没有这样的特征 ;(4 )LTC登陆后 ,其高层与中纬度急流靠近 ,增强了其向东北方向的高空流出气流 ,而STC不存在这样一支流出气流 ;(5 )LTC登陆后 ,摩擦使其能量耗损 ,但从中高层环境中获得了能量 ,而STC登陆后 ,有同样的能耗却无明显的环境能量补给。因此 ,当一个热带气旋登陆后 ,从其移动趋势、与水汽通道的连结、与斜压锋区的关系和高空流出气流等特征 ,可以初步判断其是长久维持还是迅速衰减。 相似文献
18.
2018年秋季（9—11月）大气环流特征为：北半球极涡呈偶极型分布,中高纬度西风带呈5波型分布,且强度较夏季增强。9—10月,副热带高压位置偏西,强度偏强,热带气旋活动频繁;中高纬度西风带较为平直,槽脊活动不明显;11月,经向环流增大,冷空气势力增强。我国近海海域出现了13次8级以上的大风过程,其中6次主要是由冷空气和热带气旋共同影响造成的,冷空气大风过程有5次,热带气旋影响的大风过程有2次。我国近海浪高在2 m以上的海浪过程有10次。西北太平洋和南海共生成8个台风和1个热带低压,全球其他各大洋共有28个热带气旋,较常年偏多。海面温度整体呈下降趋势。未出现雷暴大风和大范围的海雾过程。 相似文献
19.
斜压切变基流中横波型扰动的特征波动 Ⅱ:谱函数 总被引：3，自引：0，他引：3
“斜压切变基流中横波型扰动的特征波动Ⅰ谱点分布”一文中分析了斜压切变基流中横波型扰动的谱点分布，这里又对其谱函数进行了分析讨论。结果表明当基流在垂直方向存在切变时，重力惯性波与涡旋波的谱函数在垂直方向上均可出现临界层，临界层的高度随频率σ而变化，即重力惯性波与涡旋波都存在连续谱，但涡旋波与重力惯性波连续谱的结构却不同；对天气尺度扰动，两支重力惯性波和1支涡旋波的连续谱不重叠，此时每支波动仅有1个临界层；而对次天气尺度的扰动，重力惯性波与涡旋波的连续谱区会发生重叠，在连续谱的重叠区，重力惯性波仍只有1个临界层，但涡旋波则可以有2个或3个临界层。无论是涡旋波还是重力惯性波其连续谱的波包随时间都是衰减的，但涡旋波波包比重力惯性波波包衰减得慢。 相似文献
20.
Barotropic Process Contributing to the Formation and Growth of Tropical Cyclone Nargis 总被引：1，自引：0，他引：1
This study reveals the barotropic dynamics associated with the formation and growth of tropical cyclone Nargis in 2008,during its formation stage.Strong equatorial westerlies occurred over the southern Bay of Bengal in association with the arrival of an intraseasonal westerly event during the period 22-24 April 2008. The westerlies,together with strong tropical-subtropical easterlies,constituted a large-scale horizontal shear flow,creating cyclonic vorticity and thereby promoting the incipient disturbance that eventually evolved into Nargis.This basic zonal flow in the lower troposphere was barotropically unstable,with the amplified disturbance gaining more kinetic energy from the easterly jet than from the westerly jet during 25-26 April. This finding suggests that more attention should be paid to the unstable easterly jet when monitoring and predicting the development of tropical cyclones.Energetics analyses reveal that barotropic energy conversion by the meridional gradient of the basic zonal flow was indeed an important energy source for the growth of Nargis. 相似文献