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1.
通过对９６０８台风低压造成的河南省大暴雨过程的特点，影响系统，物理量及中尺度云雨团等方面的分析指出：登陆台风的大暴雨过程是地形及多种尺度天气系统相互作用及恰当配置的结果暴雨中心的产生与环境场对流不稳定能量积蓄爆发和“Ｖ”地形引起反向气压梯度力有关。同时还提出了加密红外卫星云图的云顶温度与降水经度有较好的对应关系。 相似文献
2.
神农架林区西南坡为局地暴雨灾害多发区。利用常规资料、多普勒雷达资料和区域自动站资料,分析了导致神农架林区西南坡2014年8月6日至7日夜间连续两场短时暴雨过程中MCS发生发展的天气背景及结构特征,并探讨了神农架山区复杂地形构造对西南坡暴雨的增幅作用。结果表明:1)中高层天气系统强迫弱时,副高边缘地面暖低压倒槽及850 h Pa气旋性弯曲区与辐合的发生发展可能是造成这类局地强降水天气的触发系统,地面弱冷空气的入侵有利于降水的维持和加强。2)两次局地暴雨过程均是由中β尺度对流系统影响产生的,降水历时短、强度大,雨区移动呈现局地性,具有明显的中尺度强对流系统特征,分别属前导层状云与尾随层状云中尺度对流系统型。3)第一场暴雨过程以对流降水为主,回波较强;第二场暴雨过程回波质心低且层状云特征比较突出,但维持时间相对较长,降水效率更高。4)神农架西南坡坡度大,海拔高度高,地形的动力抬升和辐合作用促使上升运动加强,地形强迫抬升作用显著不仅对局地对流触发、降水增幅有重要作用,而且会影响中尺度对流系统结构,这可能是神农架林区西南坡暴雨高发的重要原因。 相似文献
3.
从天气系统背景、FY-2C卫星产品、水汽通量分布特征和大气稳定度特征等方面,分析了受台风低压倒槽与东移锋面云系的共同影响,于2005年7月21日夜间到23日邯郸市出现的大范围的暴雨天气,结果发现500 hPa槽前中尺度切变线是直接影响产生暴雨的重要系统;地形作用使迎风坡降水增强;中尺度对流云团和雨团关系密切,暴雨中心位于OLR和TBB低值区下面;西部山区的暴雨区水汽主要来源于南海、东海,东部平原大暴雨水汽主要来源于南海;暴雨区上空低层为对流不稳定,高层为对称不稳定. 相似文献
4.
自贡地区暴雨产生，从天气分析和物理量诊断分析知，是在５００ｈＰａ青藏高原东部低槽结合７００ｈＰａ西南涡或川西低槽东移的天气背景下，由大气内部不平衡所激发的中尺度散度辐合增长，增强了自贡西部邻域（２００公里）内的中尺度系统，在偏南气流和适当的水汽，能量条件下所产生的。据此，研制了由天气模式，物理量诊断模式，多维场相关暴雨落点分析三部分构成的自贡地区暴雨短期预报准自动化系统。 相似文献
5.
从天气系统背景、FY-2C卫星产品、水汽通量分布特征和大气稳定度特征等方面,分析了受台风低压倒槽与东移锋面云系的共同影响,于2005年7月21日夜间到23日邯郸市出现的大范围的暴雨天气,结果发现:500hPa槽前中尺度切变线是直接影响产生暴雨的重要系统;地形作用使迎风坡降水增强;中尺度对流云团和雨团关系密切,暴雨中心位于OLR和TBB低值区下面;西部山区的暴雨区水汽主要来源于南海、东海,东部平原大暴雨水汽主要来源于南海;暴雨区上空低层为对流不稳定,高层为对称不稳定。 相似文献
6.
利用常规观测资料、自动区域站雨量、卫星TBB资料、雷达资料,对恩施州2016年6月24—25日发生的一次大范围暴雨过程进行分析。结果表明:本次强降水,具有典型的两槽一脊"单阻型"梅雨环流特征,在有利的大尺度环流背景下,在高空槽、低层低涡切变、西南急流、地面中尺度辐合线等中尺度天气系统的共同影响、相互作用下,形成了此次大范围强降水。此次暴雨空间上分布不均,局地性强,表现为明显的中尺度对流性特征,雷达回波图上降水性质表现为混合型降水,暴雨的直接影响系统是中β尺度对流系统,且中β尺度对流系统在多个中尺度对流云团合并后加强,时间尺度约为5 h。此次暴雨过程是在上干冷下暖湿强的大气层结不稳定条件下,梅雨锋、边界层辐合线和地形槽的触发作用将前期积累的能量释放产生的强对流天气,同时,副高外围西南气流将南海和西太平洋的水汽向恩施输送,为暴雨的发生提供了有利的条件。 相似文献
7.
2020年1月24—25日广西出现一次罕见区域性强对流,过程伴随近20年最大范围冰雹天气。南支槽异常发展东移是此次过程的扰动背景,提供了必要的热动力及水汽条件。基于波作用通量及多尺度能量诊断方法,利用常规观测资料、风云卫星资料、NCEP/NCAR以及ERA5再分析资料,从能量转化角度对此次引发区域强对流的南支槽过程进行研究。结果表明:整个过程中纬度和副热带西风急流均较历史同期偏强,有利于上游扰动向下游传播。欧亚大陆上空存在南北两支活跃Rossby波列。源自地中海一带的南支副热带西风急流Rossby波列对南支槽起到主要调控作用,Rossby波能量沿急流频散并在南支槽区辐合,促进了南支槽发展东移。源自北大西洋阻塞高压内部的北支Rossby波列则起到协同作用,促进了乌拉尔山冷槽发展及其与中东槽合并,从而增强了南支波列向下游的传播,进一步增强南支槽;天气尺度有效位能向天气尺度动能的转换以及由背景场向天气尺度的动能输送是南支槽天气尺度扰动发展的主要贡献项。动能的平流输送将获得的天气尺度动能在空间上再分配,维持南支槽稳定发展东移。在此背景下,天气尺度向对流尺度的降尺度动能串级是区域强对流最主要能量... 相似文献
8.
梅雨锋云系的结构特征及其成因分析 总被引：7，自引：9，他引：7
利用逐时卫星遥感观测资料和地面测站的降水资料，分析了江淮流域2003年6月22～26日暴雨过程中梅雨锋云系的演变、结构特征和形成原因。结果表明，梅雨锋云系为一条TBB的低值带，稳定少动，其上分布着中尺度对流系统（MCS），而中尺度对流系统是由不同尺度、不同强度．的对流单体（包括中β和中γ尺度对流单体）组成的，从而使得梅雨锋云系产生不均匀的降水分布（包括时间上和空间上）。在该暴雨过程中，梅雨锋云系充分体现了中尺度对流系统中所包括的3类组织结构形式。梅雨锋云系与中高纬度云系或热带辐合带云系之间的相互作用与暴雨过程关系密切，梅雨锋云系的维持和发展与强大的黄淮气旋云系直接相关，它是江淮流域上空冷暖气流交汇的结果。 相似文献
9.
地面加热与高原低涡和对流系统相互作用的一次个例研究 总被引：4，自引：8，他引：4
本文利用NCEP-FNL再分析资料、FY-2E卫星TBB数据、CMORPH降水资料,通过热力学和动力学诊断分析并结合中尺度天气模式WRF的数值模拟试验,研究了2012年6月下旬青藏高原一次东移对流系统的生成发展机制以及与地面加热相互作用的物理过程。结果表明,高原中西部地面感热加热是高原低涡生成、发展和东移的主导因子。而东移的高原低涡通过加强偏北、偏南气流形成的辐合带,进而触发高原东部对流系统的生成。同时,高原对流系统降水产生的凝结潜热释放也加强了东移高原低涡的强度,这表明地面加热与高原低涡和对流系统之间存在一种正反馈机制。数值试验结果进一步表明,除了适当的背景环流外,高原地面潜热通量能够增强中低层大气的不稳定性,为对流系统的发生发展积累能量,造成有利于对流降水的热力环境。 相似文献
10.
青衣江流域“93．7”特大暴雨天气分析 总被引：4，自引：0，他引：4
青衣江流域是我国著名的多暴雨区。从天气学角度，对１９９３年７月２８～２９日，该区域产生的一次特大暴雨天气过程的大尺度环流及天气尺度影响系统、物理量场特征、中尺度特征、地形作用等分别作了较深入的分析。结果表明：此过程为一典型的青衣江流域中β尺度暴雨过程。它产生的原因为，１００ｈＰａ南亚高压东西向脊线位于该区域上空，５００ｈＰａ青藏高压东移后高原低涡切变迅速增强并促使地面──７００ｈＰａ中尺度地形涡旋强烈发展，而迎风坡和喇叭口地形对暖湿空气的强迫辐合和抬升，在很大程度上，加大了降水强度．太阳对地表面辐射增温及边界层的感热、潜热汇对中尺度地形涡旋的形成和发展起重要作用。 相似文献
11.
Diurnal variations of two mountain-plain solenoid （MPS） circulations associated with ＂first-step＂ terrain [Tibetan Plateau （TP）] and ＂second-step＂ terrain （high mountains between the TP and ＂east plains＂） in China and their influence on the south west vortex （SWV） and the mei-yu front vortex （MYFV） were investigated via a semi-idealized mesoscale numerical model [Weather Research and Forecasting （WRF）] simulation integrated with ten-day average fields （mei-yu period of 1-10 July 2007）. The simulations successfully reproduced two MPS circulations related to first and second-step terrain, diurnal vari- ations from the eastern edge of the TP to the Yangtze River-Huaihe River valleys （YHRV）, and two precipitation maximum centers related to the SWV, MYFV. Analyses of the averaged final seven-day simulation showed the different diurnal peaks of precipitation at different regions： from the aftemoon to early evening at the eastern edge of the TP; in the early evening to the next early morning in the Sichuan Basin （SCB）; and in the late evening to the next early morning over the mei-yu front （MYF）. Analyses of individual two-day cases confirmed that the upward branches of the nightlime MPS circulations enhanced the precipitation over the SWV and the MYFV and revealed that the eastward extension of the SWV and its con vection were conducive to triggering the MYFVs. The eastward propagation of a rainfall streak from the eastern edge of the TP to the eastern coastal region was primarily due to a series of convective activities of several systems from west to east, including the MPS between the TP and SCB, the SWV, the MPS between second-step terrain and tile east plains, and the MYFV. 相似文献
12.
Persistent heavy rainfall events (PHREs) over the Yangtze–Huaihe River Valley (YHRV) during 1981–2020 are classified into three types (type-A, type-B and type-C) according to pattern correlation. The characteristics of the synoptic systems for the PHREs and their possible development mechanisms are investigated. The anomalous cyclonic disturbance over the southern part of the YHRV during type-A events is primarily maintained and intensified by the propagation of Rossby wave energy originating from the northeast Atlantic in the mid–upper troposphere and the northward propagation of Rossby wave packets from the western Pacific in the mid–lower troposphere. The zonal propagation of Rossby wave packets and the northward propagation of Rossby wave packets during type-B events are more coherent than those for type-A events, which induces eastward propagation of stronger anomaly centers of geopotential height from the northeast Atlantic Ocean to the YHRV and a meridional anomaly in geopotential height over the Asian continent. Type-C events have "two ridges and one trough" in the high latitudes of the Eurasian continent, but the anomalous intensity of the western Pacific subtropical high (WPSH) and the trough of the YHRV region are weaker than those for type-A and type-B events. The composite synoptic circulation of four PHREs in 2020 is basically consistent with that of the corresponding PHRE type. The location of the South Asian high (SAH) in three of the PHREs in 2020 moves eastward as in the composite of the three types, but the position of the WPSH of the four PHREs is clearly westward and northward. Two water vapor conveyor belts and two cold air conveyor belts are tracked during the four PHREs in 2020, but the water vapor path from the western Pacific is not seen, which may be caused by the westward extension of the WPSH. 相似文献
13.
Based on the previous statistical analysis of mesoscale convective systems(MCSs)over the second-step terrain along Yangtze-Huaihe River Valley,eight representative long-lived eastward-propagating MCSs are selected for model-based sensitivity testing to investigate the initiation and evolution of these types of MCSs as well as their impact on downstream areas.We subject each MCS to a semi-idealized(CNTL)simulation and a sensitivity(NOLH)simulation that neglects condensational heating in the formation region.The CNTL experiment reveals convection forms in the region downstream of a shortwave trough typified by persistent southwesterly winds in the low-to midtroposphere.Upon merging with other convective systems,moist convection develops into an MCS,which propagates eastward under the influence of mid-tropospheric westerlies,and moves out of the second-step terrain.The MCS then merges with pre-existing local convection over the plains;the merged convection reinforces the cyclonic wind perturbation into a mesoscale vortex at 850 hPa.While this vortex moves eastward to regions with local vortex at 850 hPa,another vortex at 925 hPa is also intensified.Finally,the vortices at 850 and 925 hPa merge together and develop into a mesoscale convective vortex(MCV).In contrast,MCSs fail to form and move eastward in the NOLH experiment.In the absence of eastward-propagating MCSs,moist convection and mesoscale vortices still appear in the plains,but the vortex strength and precipitation intensity are significantly weakened.It is suggested the eastward-propagating MCSs over the second-step terrain significantly impact the development and enhancement of moist convection and vortices in the downstream areas. 相似文献
14.
梅雨期青藏高原东移对流系统影响江淮流域降水的研究 总被引：5，自引：2，他引：3
利用GOES-9和FY-2C卫星TBB资料、1°×1°的NCEP再分析资料以及常规地面观测资料对2003和2007年梅雨期内青藏高原东移对流系统影响重庆、四川以及江淮梅雨锋地区降水的主要方式作了研究。结果表明,2003和2007年梅雨期内,青藏高原东移对流系统影响下游地区降水主要存在4种方式:(1)高原上的动力辐合中心伴随高原对流系统东移,影响所经地区的降水,该种影响方式较为常见,持续时间较长,影响范围较广。(2)高原对流系统移出高原后在四川盆地引发稳定少动的西南低涡,触发一系列暴雨过程,此种影响方式持续时间较长,主要影响地区为四川和重庆(往往会造成强度很大的暴雨),当西南低涡以东盛行较强西南风时,向梅雨锋的动能输送较强,这十分有利于梅雨锋地区对流活动和降水的加强。(3)高原东移对流系统在四川盆地触发西南低涡,西南低涡生成后,在引导槽的作用下沿梅雨锋东移,沿途引发一系列暴雨,此种影响方式持续时间最长,波及范围最广。(4)对流系统东移出青藏高原后直接影响下游地区,此种影响方式最为常见,但其影响时间最短,强度最小。对环境场的分析表明,高原强对流往往发生在500hPa影响槽槽区附近的上升运动区,当200hPa高空急... 相似文献
15.
近30年我国南方区域持续性暴雨过程的分类研究 总被引：5，自引：0，他引：5
利用中国站点日降水资料对1981~2011年我国南方地区区域持续性暴雨(PHREs)进行了分类研究。按照区域内至少连续5 d或5 d以上有不小于10个格点[分辨率0.25o(纬度)×0.25o(经度)]出现大于等于50 mm降水且相邻两日雨带重合率不小于20%的标准,采用客观分析的方法分别挑选出我国江淮区域和华南区域PHREs。江淮区域非台风影响的PHREs 31例,集中发生在6月中旬到7月中旬,平均持续8.29 d,华南非台风影响的PHREs 34例,集中发生在6~7月,平均持续6.24 d,这两类事件的发生频次和强度均呈年代际增长。江淮区域受台风影响的PHREs 4例,集中发生在7月中下旬到8月初。华南受台风系统影响的PHREs 31例,集中发生在7~9月,此类事件的发生频次和系统强度在2000年以后均明显上升。采用场相关的客观分类方法对非台风影响的PHREs进行较为细致的分类,将江淮区域持续性暴雨事件分为A型(主雨带在长江以南)、B型(主雨带在长江以北)和C型(主雨带在长江沿江地区),将华南区域持续性暴雨事件分为E型(主雨带在云贵高原以东)和F型(主雨带位于云贵高原和广西),该分类将为下一步的机制研究提供帮助。 相似文献
16.
夏季南亚高压（SAH）中心呈青藏高原和伊朗高原双模态分布,表现为东—西振荡的形式。同时,SAH的东缘还存在规律性的向东亚地区东伸或西退至青藏高原,表现为另一种形式的东西振荡。本文利用NCEP1逐日再分析资料、APHRODITE逐日降水数据以及印度地区逐日降水数据,研究了SAH这两类东—西振荡的联系以及它们对亚洲地区环流和天气影响的差异。结果表明,SAH中心的双模态东—西振荡位相可显著影响其东缘东伸/西退的发生及其幅度。尽管在SAH中心呈青藏高原和伊朗高原模态时,均可以出现SAH东缘的向东亚东伸,但青藏高原模态下发生东伸的频率明显高于伊朗高原模态;在伊朗高原模态时则更容易出现SAH东缘的西退。而且,在青藏高原模态下发生的SAH东缘东伸的幅度也比伊朗高原模态时更大。进一步研究发现,SAH中心的双模态东—西振荡主要与印度北部及整个青藏高原地区的降水异常型密切联系,并与异常降水有关的热力和动力作用变化相耦合。而SAH东缘的东伸/西退则通过引起西太副高的西进/东退,与东亚地区偶极子型的降水异常（青藏高原中东部、长江与黄河之间的中下游地区的降水异常与长江以南地区的相反）相联系。此外,SAH中心为青... 相似文献
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By using barotropic model equations, this article analyzed the characteristics of Rossby waves, the propagation features of wave energy and the influence of dynamic and thermal effects of the Tibetan Plateau on Rossby waves, and the focus is on discussing the plateau's topographic gradient effects on atmospheric Rossby waves. Then based on the WRF3.2 and the NCEP/NCAR FNL reanalysis data, we devised comparative tests of changing the plateau's topographic gradient and simulated a process of persistent heavy rain that happened in May 2010 in South China. The results are shown as follows. The Tibetan Plateau’s topography is conducive to the formation of atmospheric Rossby waves. while the plateau's terrain, its friction and heating effects can all make the atmospheric Rossby waves develop into the planetary waves; The effects of plateau's north and south slopes on the Rossby wave’ phase velocity is opposite, and when the slope reached a certain value can the quasi-steady normal fluctuations be generated; Simultaneously, due to the plateau's topographic gradient, descending motion appears at the west side of the plateau while ascending motion appears at the east side, and the vertical movement increased with the amplification of topographic gradients. The plateau's topographic gradient also obviously amplified the precipitation in South China, and the rainfall area increased with the amplification of topographic gradients and gradually moved from south to north and from west to east, which is conducive to the occurrence and development of convective activities in the downstream areas of the Tibetan Plateau; Moreover, for the plateau’s dynamic and thermal effects, the Rossby wave’ propagation shows upstream effects of energy dispersion, so the plateau can then affect the weather in downstream areas. Moreover, the wave group velocity increased with the degree of topographic slope. 相似文献
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This paper attempts to reveal a long-distance-relayed water vapor transport(LRWVT) east of Tibetan Plateau and its impacts. The results show that from August to October, east of Tibetan Plateau, there exists a unique LRWVT,and the water vapor from the South China Sea and the western Pacific can affect the Sichuan Basin, Northwest China and other Chinese regions far from the tropical sea through this way. From August to October, the precipitation of the region east of the Plateau is closely linked both in the intra-annual and inter-annual variations, and the LRWVT from the South China Sea and the western Pacific is an important connection mechanism. The large-scale circulation background of the LRWVT impacting the precipitation of the region east of the Plateau is as follows: At high levels,the South Asian High is generally stronger than normal and significantly enhances with its northward advance and eastward extension over the region east of the Plateau. At mid-level, a broad low pressure trough is over Lake Balkhash and its surroundings, and the Western Pacific Subtropical High(WPSH) is northward and westward located, and the western part of Sichuan Basin and the eastern part of Northwest China are located in the west and northwest edge of WPSH. 相似文献
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Comparison of two types of persistent heavy rainfall events during sixteen warm seasons in the Sichuan Basin 
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下载免费PDF全文 Yuanchun Zhang Jianhua Sun Luqi Zhu Huan Tang Shuanglong Jin Xiaolin Liu 《大气和海洋科学快报》2021,14(6):48-53
本文筛选出四川盆地西部(盆西型)和盆地东部(盆东型)持续性暴雨个例,深入对比两类持续性暴雨的大气环流特征和直接造成持续性暴雨的西南低涡维持的机理.四川盆地的短波槽和西太平洋副热带高压的配置有利于持续性暴雨的维持,盆东型的降水强度较盆西型个例强,高空急流位置偏南,南亚高压的强度更强,高层辐散更强,对流层中层副热带高压偏东偏南.盆西型的水汽输送主要来自南海,而盆东型的水汽输送主要来自南海和孟加拉湾.合成涡度收支的结果表明散度项是两类持续暴雨中西南涡维持的主要原因,但盆西型中,垂直平流的作用更强. 相似文献