A Deep Learning Approach for Forecasting Thunderstorm Gusts in the Beijing–Tianjin–Hebei Region

Thunderstorm gusts are a common form of severe convective weather in the warm season in North China,and it is of great importance to correctly forecast them.At present,the forecasting of thunderstorm gusts is mainly based on traditional subjective methods,which fails to achieve high-resolution and high-frequency gridded forecasts based on multiple observation sources.In this paper,we propose a deep learning method called Thunderstorm Gusts TransU-net(TGTransUnet)to forecast thunderstorm gusts in North China based on multi-source gridded product data from the Institute of Urban Meteorology(IUM)with a lead time of 1 to 6 h.To determine the specific range of thunderstorm gusts,we combine three meteorological variables:radar reflectivity factor,lightning location,and 1-h maximum instantaneous wind speed from automatic weather stations(AWSs),and obtain a reasonable ground truth of thunderstorm gusts.Then,we transform the forecasting problem into an image-to-image problem in deep learning under the TG-TransUnet architecture,which is based on convolutional neural networks and a transformer.The analysis and forecast data of the enriched multi-source gridded comprehensive forecasting system for the period 2021–23 are then used as training,validation,and testing datasets.Finally,the performance of TG-TransUnet is compared with other methods.The results show that TG-TransUnet has the best prediction results at 1–6 h.The IUM is currently using this model to support the forecasting of thunderstorm gusts in North China.

Seasonal Variability of Rainfall and Thunderstorm Patterns in Kenya

This paper presents an analysis of spatial and temporal variation of rainfall and thunderstorm occurrence over Ken-ya from January 1987 to December 2017.The meteorological data used were obtained from the Kenya Meteorological Department(KMD)for the same period.This included the monthly thunderstorm occurrences and rainfall amounts of 26 synoptic stations across the country.The characteristics of monthly,seasonal and annual frequency results were presented on spatial maps while Time series graphs were used to display the pattern for annual cycle,seasonal varia-tions and the inter-annual variability of rainfall amounts and thunderstorm occurrences.A well-known non-parametric statistical method Mann Kendall(MK)trend test was used to determine and compare the statistical significance of the trends.Thunderstorm frequencies over the Eastern,Central and Coast regions of the country showed a bimodal pattern with high frequencies coinciding with March-April-May(MAM)and October-November-December(OND)rainy sea-sons.Very few thunderstorm days were detected over June-July-August(JJA)season.The areas to the western part of the country,near Lake Victoria,had the highest thunderstorm frequencies in the country over the three seasons:MAM,JJAS and OND.The annual frequency showed a quasi-unimodal pattern.These places near Lake Victoria showed sig-nificantly increasing thunderstorm trends during the MAM and OND seasons irrespective of the rainfall trends.This shows the effects of Lake Victoria over these areas,and it acts as a continuous source of moisture for thunderstorm for-mation.However,most stations across the country showed a reducing trend of thunderstorm frequency during MAM and JJA seasons.The importance of these findings is that they could support various policy makers,and users of cli-mate information,especially in the agriculture and aviation industries.

Thunderstorm and Lightning Activities over Western Pacific,Northern Indian Ocean and South China Sea Along with Their Adjacent Lands

The Lightning Imaging Sensor(LIS)and Radar Precipitation Feature(RPF)data are used to investigate the activities and properties of lightning and thunderstorms over a region including the Western Pacific,northern Indian Ocean and the South China Sea along with their adjacent lands.The lands feature significantly more frequent lightning flashes and thunderstorms than the oceans,especially the open oceans.The highest densities of lightning and thunderstorm occur over the Strait of Malacca and the southern foothills of the Himalayas.Over the ocean regions,the Bay of Bengal and the South China Sea are characterized by relatively frequent lightning and thunderstorm activities.Larger average spatiotemporal size and optical radiance of flashes can be found over the oceans;specifically,the offshore area features the most significant flash duration,and the open ocean area is characterized by the greatest flash length and optical radiance.The smallest average values of flash properties can be found over and around the Tibetan Plateau(TP).The oceanic thunderstorms tend to have a significantly larger horizontal extent than the continental thunderstorms,with the former and latter having the average area of the regions with radar reflectivity larger than 20 dBZ,generally over 7000 km^(2) and commonly below 6000 km^(2),respectively.The TP thunderstorms show the smallest horizontal extent.Meanwhile,the oceanic thunderstorms exhibit greater 20 dBZ but smaller 40 dBZ top heights than the continental thunderstorms.The average flash frequency and density of the oceanic thunderstorms are typically less than 5 fl min^(-1) and 0.3 fl 100 km^(-2) min^(-1),respectively;in contrast,the corresponding values of continental thunderstorms are greater.It is explored that the regions associated with strong convective thunderstorms are more likely to feature small-horizontal-extent and low-radiance flashes.

Radio-Acoustic Study of Thunderstorms

The observation, in the past, that a thunderstorm perturbed the transmissions of an old vacuum tubes radio with noise discharges in correspondence with lightnings, suggested the possibility of radio-acoustic study of thunderstorms. The noise discharges appeared to convey not only information about lightnings, but also about any other thunderstorm electromagnetic phenomena generating noise discharges. The low-cost instrumentation involved in the radio-acoustic study, comprised a radio Telefunken mod. T33B, a 15 m long indoor wire antenna, a mobile telephone Samsung Galaxy S20 FE 5G provided with the recorder App Enregistreur vocal, a computer HP Pavillion dv5-1254eg and the s/w audio analyser Audacity. A first thunderstorm on 20 June 2023 and a second thunderstorm on 22 June 2023, both above Munich, were radio-acoustic studied. The second thunderstorm was more active than the first and released much more energy.

Prediction-Based Thunderstorm Path Recovery Method Using CNN-BiLSTM

The loss of three-dimensional atmospheric electric field(3DAEF)data has a negative impact on thunderstorm detection.This paper proposes a method for thunderstorm point charge path recovery.Based on the relation-ship between a point charge and 3DAEF,we derive corresponding localization formulae by establishing a point charge localization model.Generally,point charge movement paths are obtained after fitting time series localization results.However,AEF data losses make it difficult to fit and visualize paths.Therefore,using available AEF data without loss as input,we design a hybrid model combining the convolutional neural network(CNN)and bi-directional long short-term memory(BiLSTM)to predict and recover the lost AEF.As paths are not present during sunny weather,we propose an extreme gradient boosting(XGBoost)model combined with a stacked autoencoder(SAE)to further determine the weather conditions of the recovered AEF.Specifically,historical AEF data of known weathers are input into SAE-XGBoost to obtain the distribution of predicted values(PVs).With threshold adjustments to reduce the negative effects of invalid PVs on SAE-XGBoost,PV intervals corresponding to different weathers are acquired.The recovered AEF is then input into the fixed SAE-XGBoost model.Whether paths need to be fitted is determined by the interval to which the output PV belongs.The results confirm that the proposed method can effectively recover point charge paths,with a maximum path deviation of approximately 0.018 km and a determination coefficient of 94.17%.This method provides a valid reference for visual thunderstorm monitoring.

Analysis of Continuous Thunderstorm in One Week at Qingdao Airport Based on Sounding Data

Continuous thunderstorm occurring at Qingdao Airport in China from August 7 to 13,2022 was analyzed based on sounding data.The weather was divided into thunderstorm gale,thunderstorm and heavy precipitation,and some physical quantities and time variables which can effectively identify severe convective weather types were preliminarily obtained.The results show that CAPE was sensitive to different types of weather,but the uncertainty was relatively large.Convective temperature T_(CON),temperature difference between 500 and 850 hPa,and vertical wind shear can distinguish thunderstorm gale,thunderstorm and heavy precipitation weather obviously.Besides,K index,Showalter index,θ_(se) difference between 500 and 850 hPa were also important basis to distinguish thunderstorm and heavy precipitation weather.Thunderstorm gale can be distinguished by the 24-hour variations of K index,and the difference of dew point between 500 and 850 hPa.The 24-hour variations of(T-T_(d))_(500) and vertical wind shear can be used to distinguish between heavy precipitation and thunderstorm weather;the 24-hour variation of stratification stability Δθ_(se) can distinguish the three kinds of weather well.For the wind field,the existence of vertical wind shear was required for strong convective weather,and the 24-hour increment of thunderstorm gale and thunderstorm was larger than that of heavy precipitation.

我国大气电学研究的最新进展

大气电学主要研究地球大气和近地空间发生的电学过程及其机理和影响,其核心研究内容是雷电物理和雷暴电学。自1980年代以来,中国大气电学研究不断取得新的进展,特别是近年来,得益于高时间分辨率雷电探测技术的进步,大气电学研究不仅在雷电物理学和雷暴云电荷结构方面取得了重要成果,也在雷电和雷暴对近地空间的影响、强对流天气的雷电特征、以及雷电资料同化和预警预报等方面取得了重要进展。本文从六个方面对近五年来大气电学的主要研究进展进行回顾,包括高精度雷电探测和定位技术、雷电物理过程和机制、雷暴对中上层大气的影响、雷暴云电荷结构的观测和数值模拟、强对流天气的雷电特征与预报、雷电对气候变化的影响与响应等,最后对大气电学未来发展进行展望。

Assessment of the Impacts of Thunderstorm on Flight Operations at Murtala Mohammed International Airport,Ikeja,Lagos State,Nigeria

The inefficiency of the aviation industry and the persistent rise in aviation hazards have been linked to weather phenomena.As a result,researchers are looking for better solutions to the problem.The study examined the impact of thunderstorms on flight operations at Murtala Mohammed International Airport,Lagos.The data on thunderstorms and flight operations were sourced from Nigerian Meteorological Agency(NiMet)and Nigerian Airspace Management Agency(NAMA)respectively.In order to meet the research target,descriptive statistics(mean,standard deviation,and charts)and inferential statistics(Pearson’s Product Moment Correlation(PPMC)and Regression)were used.The significance level for all inferential analyses was set at 5%(0.05).The study revealed that 77.4%of thunderstorms occurred during the rainy season(April-October)while 22.6%occurred during the dry season(November-March).It also revealed some fluctuating movements of a thunderstorm in the study area.According to the findings,thunderstorms occur most frequently at the airport in June and less frequently in January and December.The study also discovered that thunderstorms at the airport are positively and significantly related to flight delays and cancellations,while the association between flight diversions and thunderstorm occurrence is positive but statistically insignificant.Furthermore,flight delays,flight diversions,and flight cancellations interact positively among themselves.The regression result of the study revealed that a 1%increase in thunderstorm occurrence leads to a 19.4%increase in flight delay,a 7.1%increase in flight cancellation,and a 4.3%increase in flight diversion.As a result,the study presented various regression models that may be utilized to make predictions.The study proposes consistent thunderstorm observation at the airport and steady forecasts using the regression models,based on the findings.However,it further recommends that pilots,air traffic controllers,and meteorologists be trained and retrained so that they can provide better and more efficient services.

湖北冷季高架雷暴天气分类及环境参数特征分析

利用常规观测资料、加密地面自动站、闪电定位仪和ERA5再分析资料,将2011—2020年湖北冷季91次高架雷暴事件,按照形成机制分为雷雨型、强对流型和雷打雪型3类,并细致归纳了3类事件的时空分布特征、大气环流背景及关键环境参数等特征。(1)湖北冷季高架雷暴雷雨型最多,强对流型次之,雷打雪型最少。3类型存在明显的时空分布差异,雷雨型主要发生在秋末冬初(11月)和冬末初春(1—2月),强对流型及雷打雪型常出现在早春2月,3月基本以强对流型为主。(2)低槽冷锋、850 hPa切变线及低空西南急流是冷季高架雷暴发生的有利环流背景,近地面为稳定的冷气团控制,逆温明显,西南低空急流沿着锋面逆温层以上的850 hPa附近触发抬升,水汽、上升运动及不稳定层结均出现在850 hPa以上。雷雨型和雷打雪型距离冷锋超过100 km以上,强对流型不足100 km。(3)850 hPa是风场转换的重要层次。强对流型850 hPa露点温度(T_(d850))、K指数、850 hPa与500 hPa温差(ΔT_(85))、850 hPa假相当位温(θ_(se850))、西南急流厚度和强度(I700)、切变线强度(S_(850))最大,中低层(850~700 hPa)垂直风切变(SL78)最小;雷打雪型对水汽和不稳定能量的要求最低,SL78最大。

大兴安岭林区雷击火成因机理及影响因素研究进展

闪电是雷击火发生的火源,森林雷击火给人类和生态环境带来了巨大损失.本研究从大兴安岭林区雷击火发生的时空规律、引燃机理、影响因素和预测预报等方面,总结梳理了国内外研究进展结合对雷击火高发区域地质背景研究分析,认为地质要素对云-地闪电有重要影响,地质多要素是雷击火发生的重要条件,并对未来研究趋势进行了探讨和展望.

基于模式物理量参数的云南雷暴大风概率预报技术研究

利用2019—2021年云南125个国家站大风数据和云南省地闪资料,统计云南雷暴大风个例,并挑选对雷暴大风有重要意义的物理量参数,结合NCEP再分析资料确定云南雷暴大风个例的物理量阈值,再基于ECMWF数值模式预报产品及确定的阈值,采用二分法进行云南雷暴大风概率预报。结果表明:在云南三次雷暴大风过程预报检验中,8月4日云南中部及东北部雷暴大风均命中,但在云南西部及西南部出现大范围的虚警,导致此次过程虚警率较高和临界成功指数较低;8月5日云南中部、东北及西北部雷暴大风预报正确,且云南西部及南部虚警范围小,虚警率较8月4日明显降低;7月7日云南自东北向西南出现大范围的雷暴大风天气过程,雷暴大风预报落区与实况基本吻合,呈现命中率高、虚警率较低的特征;三次过程命中率、临界成功指数、虚警率平均为0.873、0.203、0.789。

陕西雷暴大风时空分布和气象条件分析

分析陕西不同区域雷暴大风形成环境差异,有助于更好地掌握此类过程的热力、动力和环流特征,为该类天气的预报预警提供参考。基于2017—2022年地面观测资料、闪电资料和欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)发布的第五代全球气候再分析资料(ERA5),分析陕西雷暴大风时空分布特征,并分区域对比分析暖型雷暴大风的环境参数和环流特征。结果表明:陕北和关中东部为雷暴大风高发区,暖型雷暴大风明显多于冷型;夏季远多于其他季节,6—8月暖型雷暴大风陕北明显多于关中和陕南。雷暴大风高发时段为15:00—21:00(北京时,下同),且14:00—18:00暖型雷暴大风发生频率陕北明显高于关中和陕南。不同区域暖型雷暴大风发生前热力、动力条件存在一定差异,陕北过程前能量和水汽条件相对较弱,动力条件相对较强;陕南能量和水汽条件相对更强,动力条件相对较弱。频率高于15%的环流型为陕北西风型和反气旋配合西风型、关中西风型和反气旋配合西风型、陕南气旋配合西风型和反气旋配合西风型。陕北西风型和反气旋配合西风型,陕北位于冷涡低槽底部或低槽底部与副热带高压之间,850 hPa和500 hPa温差较大,为对流天气发生提供了一定的不稳定条件,过程平均发生位置附近有切变存在,有利于对流天气触发;关中西风型,低层偏南气流较强,温度露点差较小;陕南气旋配合西风型,T-ln P图表现为近V型且能量条件较好;关中和陕南反气旋配合西风型,T-ln P图表现为近V型且水汽条件较好。

机载双极化气象雷达雷暴回波仿真与验证

雷暴是一种短暂而剧烈的强对流天气,常伴有闪电、冰雹、强降水等危险天气,对民航飞机的飞行安全造成巨大威胁。机载气象雷达作为保证飞行器飞行安全必备的装备,用于探测与显示航路附近的实时气象信息,辅助机组人员规避危险气象。由于极化技术在气象探测方面的优势,双极化雷达成为机载气象雷达的发展方向。但是雷暴天气具有发展迅速、变化复杂,危险性高等特点,使得获取实测机载双极化气象雷达雷暴回波数据困难。为了解决这一问题,本文基于机载双极化气象雷达提出一种雷暴回波仿真方法并进行验证。方法首先利用数值预报模式WRF模式(Weather Research and Forecasting)对雷暴气象场景进行模拟;然后使用T-Matrix方法计算气象粒子的单个粒子散射振幅矩阵,同时结合场景内粒子的微物理特性,计算雷暴目标的反射率因子;最后应用雷达气象方程,基于机载气象雷达系统参数建立雷暴回波信号模型,实现机载双极化气象雷达雷暴回波信号仿真。最后,为检验方法的正确性和准确性,基于雷暴单体识别算法对回波仿真结果进行验证。通过仿真不同仰角下雷暴回波,实验结果表明,基于WRF模式的机载双极化气象雷暴回波仿真方法对雷暴天气具有良好的模拟能力,经单体识别算法验证,结果表明可准确体现雷暴单元的质心分布,结构属性和立体特征,对比实测数据,雷暴回波仿真结果与实测数据相吻合,实验结果具有真实性和准确性。

2023年3月河南省一次极端暴雪和雷电天气成因分析

选用自动气象站、双偏振雷达、风廓线雷达和ERA5再分析等资料,分析2023年3月16日河南省一次极端暴雪和雷电天气成因。结果表明:此次极端暴雪过程主要天气系统为低槽、切变线、急流以及东北冷涡。冷涡配合-39℃冷中心稳定维持,其后部冷空气持续南下,850 hPa以下形成深厚冷垫,中高层西南暖湿气流沿冷垫爬升,形成河南省典型的降雪天气类型“天南地北型”。此次强降雪区位于整层大气可降水量大于20 mm区域的北部与700 hPa强辐合中心重叠的区域,河南中西部地形的抬升作用利于此极端降雪天气发生。冷平流与其次级环流共同作用,使局地气温骤降,导致降水相态转换较预期提前,以致多站降雪量或积雪深度超历史极值。双偏振雷达零滞后相关系数产品(CC)为相态转换监测提供了重要参考。850 hPa以下大气温度均低于0℃,且2 m气温降至1℃左右,可作为降雪预报指标。辐合切变及锋面次级环流有利于高架雷暴天气出现,20 dBz回波高度超过-20℃层高度可作为产生雷暴的关键指标。

基于高密度站点的四川复杂地形下大风特征分析

基于四川省2016—2021年4—9月大风事件和闪电资料,将大风类型分为雷暴大风和一般大风,统计分析了两类大风的时空分布特征及与地形因子的关系。结果表明:四川地区两类大风均呈现高原多、盆地少的特征,大风类型普遍以一般大风为主,盆地内部分站点雷暴大风占比较高。各个分区不同类型大风发生频次均存在日变化和月变化。对于风速,盆地南部大风更强,盆地东北部和攀西地区的雷暴大风次之。对于风向,川西高原一般大风以北风和西南风为主,雷暴大风以北风为主,攀西地区和盆地不同分区的两类大风均以北风和东北风为主。大风的发生频次和风速与不同地形因子有一定的关系,不同类型大风总体变化趋势类似。发生频次均随海拔高度的增大逐渐增大,随坡度、粗糙度和起伏度的增大先增大后减小。风速随海拔高度的增大而增大,随坡度增大先增大后减小,而粗糙度和起伏度越小,平均风速和最大风速越大。

稳态雷暴冲击风作用下典型矩形梁断面风压特性数值模拟研究

为研究稳态雷暴冲击风作用下矩形梁断面的风压特性,采用大涡模拟方法,对不同径向位置下2∶1矩形梁断面的绕流场进行数值模拟,并将数值模拟值与风洞试验值进行对比。在此基础上,对矩形梁断面的绕流场和风压分布特性进行了分析,并对矩形梁断面风压功率谱及相关性进行了研究。研究结果表明:在r=0.6D jet(发展阶段)、r=1.8 D jet(成熟阶段)和r=4.0D jet(消散阶段)三个典型工况下,矩形梁表面风压系数基本沿着中心轴对称,且矩形梁距离射流中心越远,其风压系数绝对值越小。其中,迎风面风压系数均为正值,下表面及背风面风压系数均为负值,而上表面的风压系数随不同径向距离而变化显著。在r=1.8D jet位置处,气流在下表面后端发生一定程度的再附,使下表面后端的压力有所增大;在r=4.0D jet位置处,气流在上表面前端发生分离导致前端负压进一步变大。迎风面区域的旋涡已经形成稳定结构,各测点的脉动风压能量基本保持稳定,背风面的上拐角处附近能量达到最大,而上表面和下表面的前拐角处能量较低。矩形梁断面同面测点风压系数均为正相关,且风压相关性随着测点间距的增加而减小;迎风面测点脉动风压相干性较强,相干函数值在0.9左右;而上表面和背风面测点的脉动风压分别在0.05 Hz附近以及在频率低于0.2 Hz时具有很强的相干性。在气动导纳函数方面,传统的Sears函数值在雷暴冲击风环境下将不再适用。

《雷雨》复数故事系统的生成及意义指向

话剧《雷雨》中有一个在时间和空间上层层叠叠的故事系统。其生成涉及从“五四”到20世纪30年代社会文化生活的多个层面,如个性解放、阶级斗争、文化时尚、旧家庭的恶习残留和人性错乱等。这些故事源头复杂,既涉及中西文化传统,也涉及时代语境。作家曹禺在讲述这些故事的时候,运用三角恋爱叙事、家庭戏、法庭审判叙事、戏剧巧合、人物身份背景模糊化、年龄漏洞和互文等方式,将本来散乱在不同历史阶段和当时社会各个层面的文化现象,在“家庭”格局下,收集、整理、剪辑、连缀、凝聚为一个以双重乱伦故事为树干,以其他故事为枝杈的层次丰富的故事树。这个复杂的故事树及其折叠艺术,所体现的伦理指向是复杂暧昧的,并远远逸出创作主体的把控。

廊坊市雷暴大风多普勒雷达特征指标预警应用分析

利用北京、天津和沧州多普勒天气雷达对2010—2019年廊坊市发生的29次雷暴大风天气过程中的阵风锋、径向速度大值区、垂直累积液态水含量(VIL)≥40 kg·m^(-2)等预警指标进行验证分析,结果表明:51.9%的站次出现了阵风锋,其中61.0%的雷暴大风出现在主体回波移动前方中部到右侧;17 m·s^(-1)以上大风速区作为预警指标,预警的平均提前量达47.2 min。100%的弓形回波雷暴大风出现前上游及可能影响区域存在≥17 m·s^(-1)的大风速区,以此发布预警可提前37.1 min;71.4%的雷暴大风站点上空或10 km范围内VIL≥40 kg·m^(-2),平均预警提前量最高,达到52.7 min;依据带状回波前侧或右前侧出现阵风锋发布预警的平均提前量为60.6 min。73.7%的块状回波雷暴大风天气上游及可能影响区域有≥17 m·s^(-1)的大风速区。结合上游及可能影响区域≥17 m·s^(-1)和≥20 m·s^(-1)大风速区、阵风锋、VIL≥40 kg·m^(-2)出现位置可以提前30~60 min发布雷暴大风预警信号,且可更加精准地预测灾害性大风的落区、出现时间和强度。

东北冷涡背景下三类区域性强对流天气过程时空分布和环境特征对比分析

东北冷涡是造成中国暖季强对流的重要天气尺度系统之一。为对比东北冷涡与不同类型强对流过程的时空关系及其环境特征差异,基于欧洲中期天气预报中心第5代大气再分析数据和中国国家气象信息中心提供的逐时大风、降水观测资料,筛选了2017—2021年4—9月东北冷涡背景下9例雷暴大风型、9例强降水型以及8例混合型强对流天气过程,通过动态合成开展了分析研究。结果表明:(1)三类强天气过程相对于冷涡的时空分布差异明显:雷暴大风型过程,超过70%的雷暴大风出现在冷涡中心的西南部或南部;而混合型过程,超过70%的大风出现在冷涡中心的东南部或南部;混合型和强降水型过程中,短时强降水均主要出现在冷涡中心南部或东南部,但后者发生在冷涡东南部的比例更高;雷暴大风型和强降水型过程主要出现在东北冷涡的发展和成熟阶段,而混合型过程主要发生在东北冷涡的成熟阶段。(2)三类强天气过程的环流形势和环境条件差异显著。雷暴大风型过程多出现在5—6月,一般对应的东北冷涡更深厚,等温线更密集,大气环境偏干,存在气温垂直递减率大和强风垂直切变条件,雷暴大风多发生在冷涡南侧的锋区附近,对流层中、高层受干冷空气控制,叠加在低层比较浅薄的暖湿空气之上有利于大气层结条件不稳定的增强,降水粒子蒸发降温形成的下沉气流和地面冷池,叠加锋区辐合更有利于形成区域性地面强风;而强降水型过程多集中在7—8月,对应的东北冷涡强度较弱,等温线较稀疏,强降水一般出现在锋前靠近暖区一侧的强层结不稳定区域内,对应水汽充沛、整层暖湿的环境条件,中低层温差较小,风垂直切变较弱。混合型过程对应的月份和冷涡强度与强降水型过程更接近,水汽、高低层温差以及风垂直切变等环境条件介于上述两类过程之间,但下沉对流有效位能在三类过程中表现为最大。总体来看,相较于中国中、低海拔地区雷暴大风和短时强降水的环境特征而言,东北冷涡背景下的强天气过程对应更强的深层风垂直切变,具有更强的天气尺度动力强迫。

Radar Echo and Lightning Characteristics Analysis on A Strong Thunderstorm Weather in Fuxin

Based on the radar data and lightning position indicator data of strong thunderstorm weather which happened in Fuxin on July 8,2007,the relationship between the lightning activity and the radar echo was analyzed.The results showed that Fuxin area located in the cross position of T-shaped trough and was affected by the cold air which continuously glided down.The corresponding warm front on the ground advanced southward and arrived here.It was the weather background of this thunderstorm weather.The position variation of lightning occurrence was closely related to the strong echo movement of squall line,and the velocity echo clearly reflected and predicted the movement tendency of the radar echo.