长江中游夏季两场特大暴雨天气的对比分析

分析了长江中游夏季持续性暴雨或特大暴雨的大气环流形势及其主要影响系统。通过对“98．7”与“91．7”两场特大暴雨过程进行天气学对比分析，提出了长江中游夏季特大暴雨的预报思路。     

川西“95.8”特大暴雨天气分析

川西“９５．８”特大暴雨天气分析彭贵康（雅安地区气象局，邮码６２５０００）摘要从天气学角度分析了川西“９５·８”特大暴雨的大尺度环流及天气尺度影响系统；水汽输送及源地；物理量结构；边界层内空气质量、水汽、感热和潜热汇的作用；及中尺度对流云团等要素。结...     

一种暖区降水形势特征和预报着眼点

１９９７年５月８日,清远市出现了一场罕见的暖区特大暴雨,日降水量为２９５－６ｍｍ。由于降水强度大、范围小,造成了人员伤亡和巨大的经济损失。本文通过对近２０年来清远出现的与这场降水类似的暖区强降水（指大暴雨和特大暴雨,下同）进行天气学分析,总结出这类强降水的天气学特征,并指出日常预报的着眼点。本文所用资料以０８时为准。１　降水特点　　（１）强度大日降水量都在１００－０ｍｍ以上,其中“５．１２”日降水量６４０－６ｍｍ,是清远５０年来最大的日降水量,“５－８”居第二位。　　　　表１清远６次强降水出现时…     

海河南系“96.8”特大暴雨的天气剖析

利用实测资料、Ｔ６３模式和云图资料对海河南海“９６．８”特大暴雨的天气学分析发现,特大暴雨发生在副高连续北跳和副热带环流强经向型的背景下;副高、台风、中低空急流和东北路径弱冷空气的协同作用,形成稳定的暴雨云图;海河南系的ＭＣＣ发展造成了暴雨连续发生。     

乐山市“93．7．29”大暴雨天气过程分析

从天气学角度对乐山市“９３．７．２９”大暴雨天气过程进行了综合分析，造成该暴雨过程的主要影响系统的切交线、西南低涡和偏东气流，在地形的作用下，促使辐合气流加强而形成特大暴雨天气过程。该暴雨过程在雷达回波和单站气象要素上都有明显反映，这对今后预报工作有较好的参考价值。     

宁夏地区"6.8"暴雨天气过程的可能物理成因

本文应用天气学分析及诊断分析方法,对2002年6月8日发生在宁夏的罕见暴雨天气过程进行分析。研究结果表明,暴雨天气是在有利的“东高西低”降水形势下产生的,其主要的触发天气系统是500hPa冷槽、700hPa高原低涡及地面锢囚锋。从动力学理论的分析角度来说,在宁夏地区的垂直方向上风速廓线线性和非线性分布激发产生了中尺度重力惯性波以及涡旋Rossby波,这两种中尺度扰动在切变基流中有可能发生不稳定,最终导致宁夏地区“6．8”暴雨天气过程的产生。而稳定的“东阻形势”和西南低空急流的维持是暴雨爆发与持续的可能主要原因。     

陕西历史最早暴雨成因初步分析

利用天气学原理和T213提供的物理量场分析了2004-02-20发生在陕西历史上最早的暴雨过程，发现此次暴雨是在新疆分裂冷空气、高原槽、低涡切变和地面倒槽的共同影响形成的，环流形势为“东高西低”和“北槽南涡”．西南低空急流、低涡切变是此次暴雨的直接影响系统，动力结构为高层强辐散和低层强辐合．能量场具有典型的“Ω”中尺度结构，700hPa层SW低空暖湿急流是主要水汽和能量输送系统，暴雨区水汽辐合强烈，暴雨发生在水汽通量的最大梯度处，与夏季暴雨水汽特征相似。     

广西致洪暴雨的影响系统及暴雨落区分析

以“94.6”，“94．7”和“98．6”这几次引进广西特大洪涝灾害的致暴雨过程为研究的对象，对其环流形势和影响系统的特征进行分析，研究致洪暴雨与环流形势和影响影系统的关系，暴雨区与影响系统的关系。     

一次影响山东强暴雨过程的中尺度分析

利用１９９０年华北区域中尺度暴雨监测联防业务试验期间的获得的较为稠密的地面观测资料,卫星云图及常规天气图资料,对１９９０年８月中旬的一次影响山东强暴雨天气过程作了初步的天气学分析和中尺度分析,指出了直接造成这场大暴雨的中尺度系统和有利于它们发展的环境条件,文中重点讨论了中尺度天气系统及云团与雨团的关系。     

两次由热带气旋登陆粤中北行诱发的重大暴雨过程分析

１９９５年８月广西地区在９５０４、９５０５两强热带风暴登陆粤东地区以后，受与其活动相关的涡旋云团接连影响，造成了罕见的次生低涡重大暴雨天气过程（简称９５０４、９５０５过程，下同）。从天气学特征分析，两者既有许多相似之处，也有很大的差别。其一为热带辐合带内扰动西移影响，另一次则是高原东南部由极锋锋区扰动而产生的“类西南涡过程”。经过综合分析，可以认为热带气旋登陆后，其伴随着辐合带内扰动云团的强烈发展及不断西移，是桂南局地出现特大暴雨的重要原因，这要在暴雨分析中引起特别注意。     

Numerical simulation of a low-precipitation supercell thunderstorm

Summary Numerical simulations of thunderstorms using initial conditions from an Oklahoma storm event on 26 April 1984 have been carried out using the Klemp-Wilhelmson cloud model. Two thermodynamic and two horizontal wind profiles are mixed to create four initial storm environments. The two initial thermodynamic profiles are designated as moderately and highly unstable. Both hodographs have considerable vertical wind shear, with the extremely unstable profile having substantially stronger storm-relative curvature shear in the lowest few kilometers, as measured by the helicity of the environment. Storms are initialized with two different temperature-perturbation warm bubbles. A variety of storms, qualitatively covering the range observed on this day, are simulated. With a strongly sheared, moderate instability environment, the two different temperature-perturbation simulations differ qualitatively, unlike the other pairs of simulations.Of particular interest is the simulation carried out with the weaker temperature-perturbation. It displays many of the characteristics of observed low-precipitation (LP) supercell storms. Without artificially suppressing rainfall, this storm produces very little precipitation over the first 6000 s of its lifetime. During this time, there is no strong downdraft at the lowest model level and vorticity at that level is much less than the values aloft. We hypothesize that LP storms can be generated by smaller initial impulses than classic supercells in environments typically associated with a supercell storm, as speculated by Bluestein and Parks (1983), since they are more susceptible to turbulent entrainment in highly sheared environments.With 15 Figures     

川西南地区大暴雨气候特征分析

本文用1958～2010年53年的乐山、眉山、雅安三市大暴雨降水资料,从气候趋势、时空分布等方面分析了川西大暴雨的气候变化特征：1）53年内盆地西南的大暴雨主要分布在雅安东北、眉山西南、乐山西北部地区,在该区域形成一暴雨中心圈;2）大暴雨发生次数在洪雅、峨嵋、夹江、天全等地有减少趋势;而在雅安、青神、沐川则有增强趋势;3）雅安和乐山两地大暴雨次数历年分布有一定的同步性,眉山的大暴雨次数分布和雅、乐两地的关联不明显;4）三地大暴雨分布的主要特征形态为以雅安、名山、洪雅、峨嵋为中心区域的一致性分布为主;第二种主要分布形态为雅安和峨嵋两个中心的反相关状态.此外,对历史上两次特大暴雨的天气形势进行分析,揭示特大暴雨发生的背景和条件.     

Radar observations of precipitation production in thunderstorms

Abstract

Precipitation production is investigated for 9 intense thunderstorms that developed over the Lowveld in South Africa. A C‐band radar is used to observe the 3‐dimensional reflectivity pattern. Using an empirical relation between reflectivity factor and precipitation content and integrating over the storm volume provides an estimate of the total precipitation content aloft. Likewise, an area integration of the instantaneous rain rate at cloud base yields an estimate of the rate of total outflow. At their maturing stage, the storms had precipitation contents of 0.2 to 5.0 Tg and rainfall rates of about 0.3 to 2.0 Gg s^?1. The total accumulation of rain at the ground ranged from 1 to 10 Tg. The characteristic storm updraft, defined as the ratio of the area‐averaged rainfall rate to the volume‐averaged precipitation content, was about 5 ms^?1 for all storms. The time evolution of integral storm parameters is also presented and related to the overall storm development. The precipitation production values observed in the Lowveld storms compares well with previous estimates reported for large thunderstorms observed in Alberta and New England.     

华南前汛期暴雨气候特征的研究

利用华南地区26站1958-2000年逐日降水资料，对华南前汛期暴雨降水的气候特征进行了统计研究。结果表明，华南前汛期暴雨降水量和频次的变化趋势都呈略减少的特征，都有明显的年际、年代际变化的长期演变特征；华南的暴雨近50％集中发生在前汛期，其中又以福建与广东的西北部为甚，华南的西南部较小；华南前汛期的降水有近40％为暴雨，多年平均暴雨百分率的大值中心在广东沿海地区，最大可达44％，有两个小值中心，它们分别位于广西广东西部和福建，最小只有26％。     

Historic and Future Perspectives of Storm and Cyclone

In weather sciences, the two specific terms “storm” and “cyclone” frequently appear in literature and usually refer to the violent nature of a number of weather systems characterized by central low pressure, strong winds, large precipitation amounts in the form of rain, freezing rain, or snow, as well as thunder and lightning. But what is the connection between these two specific terms? In this paper, the historic evolutions of the terms “storm” and “cyclone” are reviewed from the perspective of...     

长沙黄花机场两次对流风暴特征的对比分析

利用新一代多普勒天气雷达资料、机场自动观测系统资料结合其它有关资料,对2012年9月1日和2013年7月1日发生在长沙黄花机场的两次对流风暴的特征进行了对比分析,结果表明：2012年9月1日的对流风暴属于普通单体风暴,具有尺度小、持续时间短、降水量大的特点;2013年7月1日的对流风暴属于多单体风暴,具有尺度较小、生命史较短,产生了雷暴、降水量小的特点。两次对流风暴的共同点：在很短时间内产生了大于20 m/s的地面大风（〉17 m/s）,出现了风向突变、风速骤增、气压上升、气温骤降等类似于飑线的气象要素剧烈变化过程;两次对流风暴的触发机制都是副高外围的东风波扰动。     

Temporal distribution of weather catastrophes in the USA

The temporal distributions of the nation’s four major storm types during 1950–2005 were assessed, including those for thunderstorms, hurricanes, tornadoes, and winter storms. Storms are labeled as catastrophes, defined as events causing $1 million or more in property losses, based on time-adjusted data provided by the insurance industry. Most catastrophic storms occurred in the eastern half of the nation. Analysis of the regional and national storm frequencies revealed there was little time-related relationship between storm types, reflecting how storm types were reported. That is, when tornadoes occurred with thunderstorms, the type producing the greatest losses was the one identified by the insurance industry, not both. Temporal agreement was found in the timing of relatively high incidences of thunderstorms, hurricanes, and winter storms during 2002–2005. This resulted in upward time trends in the national losses of hurricane and thunderstorm catastrophes, The temporal increase in hurricanes is in agreement with upward trends in population density, wealth, and insurance coverage in Gulf and East coastal areas. The upward trends in thunderstorm catastrophes and losses result from increases in heavy rain days, floods, high winds, and hail days, revealing that atmospheric conditions conducive to strong convective activity have been increasing since the 1960s. Tornado catastrophes and their losses peaked in 1966–1973 and had no upward time trend. Temporal variability in tornado catastrophes was large, whereas the variability in hurricane and thunderstorm catastrophes was only moderate, and that for winter storms was low.     

广东台风特大暴雨预报

使用台风年鉴，天气图，天星云图等气象资料，对１９６０－１９９１年影响广东的３９例特大暴雨台风进行了对比分析，台风特大暴雨主要是由其云系中的中尺度强降水系统造成，归纳出形成发展的概仿模式和相应环境流场特征，建立预报思路与方法。１９９４年作１５次预报试验，其准确率达７３％。     

暴雨信号发布思路

深圳2000年4月份出现了4次暴雨和大暴雨，其中“4.14”为打破历史纪录的特大暴雨。深圳市气象台所发布的黄、红、蓝色暴雨信号是历史上次数最多，最频繁之一。本文通过对这几次不同量级的暴雨过程中暴雨信号发布情况以及短期天气预报和云图、雷达和自动站等中尺度资料在暴雨预警信号发布中所发挥作用的分析，总结发布暴雨信号的发布思路；并得到十分有益的经验。     

甘肃夏季特强沙尘暴分析

夏季沙尘暴的气候特征表明,夏季是甘肃省沙尘暴的次多发季节,主要集中在民勤、鼎新、金塔。通过对一次罕见的甘肃省夏季强沙尘暴天气分析发现:高空小槽、切变线、热低压是引发夏季沙尘暴的主要天气系统,而春季沙尘暴一般是大尺度天气系统造成的;夏季沙尘暴发生前期高空急流反映并不明显,急流风速的突然加大和沙尘暴几乎同时发生,这是夏季沙尘暴预报的难点之一;沙尘暴发生前8~12 h的螺旋度场对沙尘暴预报有较好的指示意义,正值越大,沙尘暴越强,但当沙尘暴与强降水同时发生时,沙尘暴区螺旋度值明显小于强降水中心螺旋度值。