CHARACTERISTICS AND RELATIONS OF LIGHTNING AND RADAR ECHOES FOR STRONG CONVECTIVE RAINSTORMS IN YUNNAN

Based on cloud-ground lightning data and Doppler weather radar echo products, both thecharacteristics and the relations of lightning and radar echoes for strong convective rainstorms over Yunnanare analyzed during the flood season of 2007. The results show that most rainstorms are convective in whichlightning is mostly negative and the negative lightning number accounts for more than 90% of the total.Although the correlation between precipitation and the lightning number is small on the rainstorm day, thelarge day-lightning frequency usually produces heavy precipitation. Hourly evolution of precipitation andlightning frequency shows peak-style characteristics. And their evolution is very coherent in strongrainstorm, but lightning often occurs before precipitation, whose peaks are in phase with or 1-to-2-hourlagged behind that of lightning frequency. Meanwhile the peaks of positive frequency are in phase with orfall behind that of precipitation. When the wind field is heterogeneous in radial velocity, it is conducive toboth the development of convection echoes and occurrence of lightning. Strong lightning-producingconvective rainstorms correspond to strong echo fields and usually result in reflectivity above 30 dBZ andecho top ET of more than 9 km, respectively.

四川两次极端暴雨强降水特征及与雷达回波和闪电关系分析

选取了2020年8月四川两次历史性极端暴雨过程,根据量级和持续时间对强降水进行划分,分析其时空分布特征及与雷达回波和闪电的关系。结果表明:短时强降水主要发生在22时—次日03时,降水强度为30~<50 mm/h的站次最多,区域集中在盆地西部。随着降水量级的增加,站点对应的闪电密度均增大,小时平均回波、最强回波、最弱回波均呈增强的趋势。随着降水持续时间的增加,站点对应的负地闪平均强度增强。第一次过程强降水站次与闪电频次的高值中心具有良好的对应关系。第二次过程随着降水量级增大,对应的回波均方根误差减小,而第一次过程则相反。

铜鼓及上游地区短时强降水回波特征分析

为了开展铜鼓县大暴雨过程中短时强降水的预报预警工作,文章利用铜鼓县、平江县和浏阳市雨量资料、流域地形资料、天气图、雷达回波等资料,对2013—2022年铜鼓、平江、浏阳在大暴雨事件中的短时强降水个例进行回波特征分析。结果表明:2013—2022年,铜鼓共出现大暴雨日10次,平江出现7次,浏阳出现4次;21次大暴雨中降水量≥30 mm/h的短时强降水有14次,几乎每次大暴雨都会出现降水量≥20 mm/h的短时强降水;500 hPa低槽、200 hPa出流区、850 hPa西南急流和地面辐合线有利于形成铜鼓及上游地区的大暴雨天气;铜鼓及上游地区短时强降水的雷达回波特征主要有絮状回波带(团)和絮状回波带中的短带回波两种;短时强降水回波的垂直结构主要特征为45 dBZ回波顶高为5 km~7 km,回波呈“直上直下”结构。研究结果为铜鼓短时强降水预报预警提供了分析依据。

一次有台风影响的广元市中东部暴雨过程分析

利用地面自动站降水资料、MICAPS高空实况资料、雷达资料和数值预报资料,对2019年7月19日广元市中东部出现的一次暴雨天气过程进行分析。结果表明,暴雨过程期间,受高空低值系统和低层暖湿气流的共同影响,同时伴随有台风活动,低层水汽条件和能量条件充沛。台风在此次过程中的作用,一是阻挡高空低值系统的东移,使影响系统较长时间维持在暴雨区;二是台风北侧偏东风气流将大量水汽源源不断向暴雨区输送。低涡切变线有利于水汽的辐合上升,在不稳定的暖湿大气层结中,地面弱冷空气入侵触发不稳定能量的释放。雷达特征显示广元市中东部为明显的片状混合云回波,中心回波强度超过45 dBZ,与强降雨中心落区一致。此次过程数值预报对形势的预报较为准确,对量级预报也有较好把握,但对落区预报较实况存在一定偏差,仅具有一定的参考价值。

孝感市一次强降水成因及可预报性分析

通过对2022年7月19-20日孝感市强降水成因及可预报性进行分析,可为今后暴雨分析研究和预警预报提供参考借鉴。利用常规天气图、区域自动气象站、雷达回波等实况资料,EC等模式分析预报资料,运用天气学方法进行比较分析。结果表明:①孝感市强降水在受高层南亚高压反气旋环流控制,副热带高压加强北抬、西北冷槽东移影响的环流背景下发生的,第一阶段强降水主要是受低层暖式切变线北抬、西南急流和地面暖性低压倒槽等共同结果,第二阶段强降水主要是受低层冷式切变线、西南急流和地面江淮气旋冷锋等共同结果。②不同数值模式对500 hPa环流形势预报都比较准确,其中EC细网格最好,对低层低涡冷切系统、急流轴位置,短期预报都有体现,但位置都略有偏差。③短期降水预报中,中尺度模式比全球模式预报的量级更大、效果更好,中尺度模式中华东模式最优。指出了本次强降水过程有一定的可预报性,在环流形势上EC细网格模式预报最好,主要影响系统,如低涡冷切、西南急流都预报比较准确,但强度和位置有一定偏差。降水预报中,华东模式、CMA_3KM模式也有很好的表现。

长江中上游一次极端暴雨天气过程成因分析

利用常规气象观测资料、气象信息综合分析处理系统Micaps 4资料、自动站实时数据和多普勒雷达资料等,通过诊断分析方法,对2020年6月27日一次极端暴雨天气过程成因诊断分析。结果表明,在有利的环流背景下,高空槽东移、中低层切变、西南低空急流及梅雨锋的共同作用形成了此次暴雨天气过程。暴雨发生在低层辐合、高层辐散的上升运动区,副高稳定维持在20°N附近,受副高阻挡,中纬度低槽和中低层切变线稳定维持,低空急流强劲,地面上形成梅雨锋,高空急流入口区右侧的强辐散使低层低值系统强烈发展,加强了上升运动,同时水汽条件充足,使得研究区出现暴雨天气。为提高研究区天气预报精准度提供参考。

2023年5月4—5日铜鼓大暴雨天气分析

为了做好铜鼓大暴雨天气的预警预报工作,文章使用江西省气象资料查询系统和铜鼓县国家基本气象站气象数据、MICAPS平台、江西雷达拼图平台和宜春SA雷达基数据反演PUP产品等资料,对2023-05-04—2023-05-05铜鼓县大暴雨过程进行分析。结果表明:铜鼓大暴雨过程中,铜鼓国家基本气象站降雨量为152.7 mm/12 h,赣西北和赣东北为两个暴雨区;铜鼓国家基本气象站地面气象要素中,2 min平均风速和分钟内最大瞬时风速均较小;在两次短时强降水出现前,2 min平均风速和分钟内最大瞬时风速都有一个峰值;气温、水汽压变化较小;本站气压在短时强降水发生前有个升压过程,在短时强降水结束后有个降压过程;短时强降水高峰期不是闪电频次最密集时段;铜鼓大暴雨的天气系统在100 hPa高度上有明显出流区、500 hPa低槽、850 hPa切变(低涡)和西南急流、地面西南倒槽,在倒槽中江西北部存在辐合线;铜鼓回波特征为絮状回波团和回波短带;45 dBZ强回波面积≥100 km~2,强盛时强回波面积为457 km~2和650 km~2;强降水回波45 dBZ回波顶高度在7 km~8 km,比低质心强降水的回波顶偏高1 km~2 km。研究结果为监测预警铜鼓飑线天气提供了分析依据。

江西大暴雨天气三种雷达回波特征分析

为了做好江西大暴雨天气的监测预警工作,基于MICAPS天气图、江西自动站和雷达拼图等数据,采用天气学、雷达气象学等原理与方法,对江西2022年4次大暴雨天气中的三种雷达回波形态进行分析,结果表明:江西大暴雨回波形态有短带回波、冷锋回波带和低涡回波团三种;短带回波当单体移动方向与回波带走向近似一致时,降水最强;冷锋回波带在东移过程中呈现顺时针转动,最后演变成东西走向;低涡回波团沿槽前西南急流朝东北方向移动,与切变线雨带合并后,回波团进一步发展壮大。研究结果旨在为江西大暴雨及短时强降水天气的短临预报提供分析依据。

“2023-03-22”乐平大暴雨强降水回波特征与应用

为了更好地预报乐平大暴雨和短时强降水天气,文章使用MICAPS天气图、乐平自动气象站雨量、雷达回波等资料,采用天气学、雷达气象学等原理和图像识别技术,对2023-03-22乐平大暴雨过程和短时强降水的回波进行分析。结果表明:大暴雨的对流性特征明显,伴有强降水、强雷电等强对流天气;探空图上具有典型的“喇叭口”结构,低槽东移,冷空气与西南气流交汇,高层辐散,地面辐合,导致强降水发生;强降水伴有显著强雷电,降水强度最大的乐平雷电密度也最大,在强降水开始时,强雷电一般超前于强降水出现,而在强降水过程之中或即将结束时,强雷电落后于强降水;TBB强中心以南等值线密集地方对流最旺盛,最易诱发强降水;在测站上游出现大范围45 dBZ以上强回波且向测站移来时,强回波面积≥300 km^(2),会导致≥30 mm/h强降水,应提前发布预警信息。研究结果对乐平大暴雨和短时强降水的监测预警、预报服务发挥指导作用。

景德镇一次罕见连续性大暴雨过程分析

为了更好预报大暴雨过程,利用常规地面、高空观测资料、WebGis雷达拼图STI产品、ncep日平均再分析资料,对2021年8月中旬,景德镇地区出现的一次罕见大暴雨过程进行分析。结果表明,此次降水过程持续时间长,强度大,同期降水位居景德镇历史首位。强降水是在有利环境场中产生的,暖强迫下的风速辐合是造成11—12日降水产生的主要原因;13—14日地面冷空气南下,大气斜压性增强,触发对流性强降水,导致连续性大暴雨天气的发生。雷达拼图上组合STI产品表明新老单体移向一致,重复经过景德镇和乐平市区,造成列车效应,最终导致大暴雨。副高较常年同期明显偏南、冷空气活动偏强偏南,导致冷暖空气强烈对峙,是造成景德镇中旬连续性大暴雨的主要原因。

2024-04-02景德镇市强降水回波与雷电分析

为了分析大暴雨天气中短时强降水与雷电分布和雷暴聚类的关系,文章使用雨量资料、天气形势、雷达拼图和“天衍”系统中雷电分布和雷暴聚类等资料,对2024-04-02大暴雨过程中短时强降水进行分析。结果表明:短时强降水中心合并使得强降水范围扩大,对短时强降水有增强作用,高空低槽、低层切变线、辐合线、西南急流、西南倒槽等天气系统促使短时强降水发生;东西走向的混合型回波带,其南侧存有≥50 dBZ的近似南北走向的对流降水回波短带;雷电分布密集区,雷暴聚类区域与短时强降水关系密切,雷暴聚类区的形成对判别雷暴的移动十分有利。研究结果为大暴雨天气中短时强降水的预警预报提供了分析依据。

铜鼓短时强降水回波特征分析

为了做好铜鼓大暴雨和短时强降水监测预警工作,使用2013-2023年铜鼓大暴雨降水资料、天气形势、雷达回波等资料,采用统计分析、天气图中尺度分析和雷达回波分析等方法,对2013-2023年铜鼓大暴雨过程进行分析。结果表明:2013-2023年铜鼓国家站大暴雨出现11次、高桥区域站4次、港口区域站4次,部分年份无大暴雨出现,短时强降水主要出现在03:00-09:00和11:00-17:00;铜鼓大暴雨天气形势上主要表现为200 hPa在赣西北为辐散分流区,500 hPa有低槽东移,850 hPa赣西北有切变线,低层为显著湿区,925 hPa和地面有辐合线;铜鼓大暴雨的回波形态是强回波短带,强回波短带强度比较强,一般为45~55 dBZ,有时能达到60 dBZ,回波长度比较短,但回波短带的降水效率较高,尤其是回波强度≥50 dBZ时,往往带来短时强降水;在预报服务中要特别注意回波短带的发展与演变。希望研究结果能为铜鼓大暴雨和短时强降水预报预警工作提供参考。

基于多普勒雷达探测技术的沿海地区暴雨预警方法

依靠单一的波束反射率特征信息,其预警结果的虚假警报比例较高,对此,提出基于多普勒雷达探测技术的沿海地区暴雨预警方法。运用多普勒雷达探测技术捕捉雷达波束反射因子后,提取隐藏的径向辐合参量,得到全面的天气雷达数据,并通过退速度模糊方法进行数据修正。以梯度下降算法为核心,对目标气象数据进行反演分析。通过TITAN算法识别暴雨云团,建立雷达回波特征匹配方法明确暴雨云团状态。最后,通过WSR-88D探测算法计算暴雨指数,实现沿海地区暴雨预警。结果表明,所提方法的虚假警报比降低了17%与24%,准确完成了沿海地区的暴雨预警。

Analysis on Formation Reason of the " 7.28" Regional Rainstorm in Zhongwei

[Objective] The research aimed to analyze formation reason of the ' 7.28' regional rainstorm in Zhongwei City.[Method] NCEP /NCAR reanalysis data and Micaps routine data were used to analyze formation reason of the regional rainstorm in Zhongwei City on July 28,2011.[Result]Under the east-high-west-low circulation situation,factors which caused this rainstorm included westerly jet at 200 hPa,cold trough at 500 hPa,low vortex and shear line at 700 hPa,quick alternation of the warm and cold airs at 850 hPa,stable northward movement of the subtropical high.Falling zone of the rainstorm was located at the right of the upper jet,the left of the low-level jet and the south of 700 hPa shear line.Analyses on the each physical quantity field showed that water vapor condition,vertical motion,energy,vorticity,divergence and wind field distribution over the rainstorm area were all beneficial for rainstorm generation.When the rainstorm occurred,radar echo mainly presented as mixed-cloud precipitation type.The echo intensity was from 30 to 45 dBz,and top height of the echo was from 7 to 8 km.[Conclusion]The research provided some experiences and theoretical guidance for future rainstorm forecast in Zhongwei City.

Analysis of a Heavy Rainstorm in Jincheng in August of 2010

[Objective] A heavy rainstorm in Jincheng in August in 2010 was expounded. [Method] By dint of the conventional meteorological data, and automatic weather station data, and Doppler radar data, one severe torrential rainstorm was analyzed from the aspect of circulation background, physical quantity field, satellite cloud image, and radar echo, etc. [Result] The rainstorm was in the circulation field of low-west-east-obstruction, and was formed under the middle and low layer shear line and low air torrent situation. The low layer shear and convergence of wind favorable to the lift of unsteady air around Jincheng. The intrusion of cold air in the low layer of convective layer and above the ground trigered such convective weather. The torrent of the low air in the southwest sent abundant water vapor to the rainstorm area. The high temperature and the moisture accumulated much unsteady energy for the generation of rainstorm. The main precipitation system of this process was the singular of convective echo which was stimulated by the ground mesoscale shear line. Under the guidance of southwest airstream of the low and middle air, the convective echo singular formed train effect by moving towards Jincheng and formed large rainstorm. Doppler radar data suggested that the characteristics of the generation, development and movement of this mesoscale rainstorm system. The strong precipitation center was in the large value area of the gradient in the back of the TBB center. [Conclusion] The study provided references for the forecast and pre-warning of temporary rainstorm of such kind.

2022年江西大暴雨回波面积识别特征分析

为了做好大暴雨天气的监测预警工作,文章使用MICAPS、自动气象站、雷达拼图等数据,采用天气学、雷达气象学等原理和回波面积自动识别等方法,对2022年江西6次大暴雨天气过程进行分析,结果表明:1)500 hPa低槽东移,低层辐合线、切变线与高空分流区重叠,大气层结不稳定,并伴有中等强度的对流有效位能和偏强K指数是江西大暴雨过程的基本天气系统和环境条件。2)大暴雨的回波具有絮状回波特征,在大范围混合性降水回波中有≥45 dBZ的回波单体、短带、回波带(团)存在,是造成短时强降水的主要回波系统;45 dBZ强回波顶高一般在6 km或以下,低质心特征明显。3)通过DBSCAN算法和散点轮廓算法计算出≥45 dBZ暴雨回波面积、回波强度、回波中心位置等特征,为预报方法提供接口数据。研究结果为江西大暴雨天气的监测预警提供了分析依据。

Comparative Analysis of Two Rainstorms in the Southwest of Hunan Province

Using NCEP 1° × 1° reanalysis data within 6 h, conventional observational data, data from regional automatic rainfall stations, satellite cloud pictures and Doppler radar data, we compared the physical conditions, dynamic and thermodynamic characteristics of two rainstorms in the southwest of Hunan Province on May 12 and June 15 in 2011. The results showed that the first process was triggered by strong cold air under unstable potential, while the second process was caused by shear line appearing from the east; during the first process, cold air divided into many parts and moved towards south, rainfall was uniform and lasted for a long time, while rainfall was relatively concentrated and strong, and lasted for a short time during the second process; the peak of K index appeared only during the second process; no sign of heavy rainfall was found from satellite cloud pictures and radar echo pictures during the first process, while obvious cloud cluster and echo ribbons could be found from satellite cloud pictures and radar echo pictures during the second process, which were the sign of heavy rainfall; slow movement of echo or little movement resulted in the second rainstorm, and constant echo intensity was the main reason for the occurrence of the second rainstorm. In addition, there was low-level southwest jet during the two processes, which provided favorable conditions for the transportation of water vapor and energy during the two processes. However, there was a great difference between the two rainstorms in the intensity and thickness of low-level jet, that is, the intensity and thickness of low-level jet during the first process were obviously weaker than these during the second process.

江西昌江流域大暴雨短时强降水特征分析

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江西袁河流域大暴雨短时强降水特征分析

为了做好江西袁河流域大暴雨的监测预警服务,文章统计了江西袁河流域2013—2022年大暴雨过程及其短时强降水特征,并从天气形势场、雷达回波特征进行了分析,得出袁河流域大暴雨短时强降水每年都会出现,在天气形势上存在一定的相似性,回波形态以絮状回波为主等结论。研究成果为了解和监测预警袁河流域特大暴雨中短时强降水提供依据。

玉山一次特大暴雨短时强降水中尺度结构分析

为了做好玉山汛期大暴雨监测预警和预报服务工作,文章使用MICAPS天气资料、自动气象站资料、江西WebGIS雷达拼图资料等,采用天气学、雷达气象学原理和方法,对2022-06-20玉山县特大暴雨过程进行分析,得出高层南亚高压外围辐散、低层切变线和辐合线形成辐合的环流配置有利于玉山县发生暴雨,玉山县附近的回波有典型的短时强降水回波特征,玉山特大暴雨回波短带走向与系统移动方向趋于一致等结论。研究结果以期为玉山大暴雨天气的预报提供判断依据。