共查询到20条相似文献，搜索用时 31 毫秒
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A. A. Sin’kevich B. Boe Yu. P. Mikhailovskii Yu. A. Dovgalyuk N. E. Veremei V. Gopalakrishnan P. Murugavel S. D. Pawar 《Russian Meteorology and Hydrology》2018,43(4):209-217
The results are presented of complex investigation of clouds in India which were seeded with a glaciogenic reagent from the aircraft. The seeding effect was assessed by the comparison of radar characteristics of the seeded clouds with the characteristics of clouds within the radar field of view. The maximum reflectivity increase in the seeded clouds in comparison with clouds in the natural cycle, an increase in the precipitation flux and specific mass of precipitated hail are observed. The merging of seeded clouds was observed during the study. It is shown that this process affects cloud characteristics resulting in the significant (by several times) increase in the precipitation flux. The measurements of electric discharges registered by the lightning detection network demonstrated that there were no lightning strikes in the seeded clouds, although the calculations indicated an increase in the electric activity of the clouds. 相似文献
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An integrated approach to real-time prediction of point rainfall is presented. This is based on the assumption that hourly rainfall at a station can be predicted by a Multivariate AutoRegressive Integrated Moving Average (MARIMA) process. The real-time calibration of the multivariate model is performed by combining radar maps and data from rain gages. Accordingly, radar maps provide the basic information for a storm tracking procedure which enables to detect the direction and the speed of storm movement. Storm tracking is used to select those stations which are characterized by the highest Lagrangian cross-correlation of observed precipitation, and which are therefore best suitable for application of the multivariate model. The parameters of the multivariate model are finally estimated using only observed rainfall at the selected stations throughout the current event. Preliminary results of an application to some events which occurred in northern Italy show that the combined use of radar and rain gages allows for an increased efficiency of the MARIMA model performances, as compared with empirical selection of stations to be considered by the multivariate model. The multivariate approach performs better also when it is compared with simple nowcasting procedures based on rain gage data or on radar data used separately. Finally, some considerations are issued in view of a systematic use of this technique to nowcast rainfall intensity in small urban or natural catchments, with a response time of less than 1 or 2 h. 相似文献
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Cloud-to-ground （CG） lightning data,storm intensity and track data,and the data from a Doppler radar and the Tropical Rainfall Measuring Mission （TRMM） satellite,are used to analyze the temporal and spatial characteristics of lightning activity in Typhoon Molave （0906） during different periods of its landfall （pre-landfall,landfall,and post-landfall）.Parameters retrieved from the radar and the satellite are used to compare precipitation structures of the inner and outer rainbands of the typhoon,and to investigate possible causes of the different lightning characteristics.The results indicate that lightning activity was stronger in the outer rainbands than in the eyewall and inner rainbands.Lightning mainly occurred to the left （rather than ＂right＂ as in previous studies of US cases） of the moving typhoon,indicating a significant spatial asymmetry.The maximum lightning frequency in the tropical cyclone （TC） eyewall region was ahead of that in the whole TC region,and the outbreaks of eyewall lightning might indicate deepening of the cyclone.Stronger lightning in the outer rainbands is found to be associated with stronger updraft,higher concentrations of rain droplets and large ice particles at elevated mixed-phase levels,and the higher and broader convective clouds in the outer rainbands.Due to the contribution of large cloud nuclei,lightning intensity in the outer rainbands has a strong positive correlation with radar reflectivity.The ratio of positive CG lightning in the outer rainbands reached its maximum 1 h prior to occurrence of the maximum typhoon intensity at 2000 Beijing Time （BT） 18 July 2009.During the pre-landfall period （0300 BT 18 July-0050 BT 19 July）,the typhoon gradually weakened,but strong lightning still appeared.After the typhoon made landfall at 0050 BT 19 July,CG lightning density rapidly decreased,but the ratio of positive lightning increased.Notably,after the landfall of the outer rainbands at 2325 BT 18 July （approximately 1.5 h prior to the landfall of the TC）,significantly higher ice particle density derived from the TRMM data was observed in the outer rainbands,which,together with strengthened convection resulted from the local surface roughness effect,might have caused the enhanced lightning in the outer rainbands around the landfall of Molave. 相似文献
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一次具有对流合并现象的强飑线系统的闪电活动特征及其与动力场的关系 总被引：7，自引：5，他引：2
受东北冷涡与副热带高压西北部暖湿气流影响,2015年7月27日北京地区爆发了一次具有明显对流单体合并特征的强飑线灾害性强对流天气过程。利用北京闪电定位网（BLNet）总闪定位、多普勒雷达和探空资料等,详细分析了此次飑线过程整个生命史期间不同对流区的总闪活动特征。结果表明,整个飑线过程以云闪为主,地闪活动以负地闪为主;对流单体合并时云闪数量激增,飑线过程后期正地闪比例跃增。93%的闪电主要分布在距对流线10 km范围内,层云区闪电较少;层云区的闪电电荷来源主要是由对流区的电荷经过过渡区输送而来,正地闪更易发生在过渡区和层云区。对流合并过程中有大量的水汽集中,垂直积分液态含水量（VIL）峰值超前闪电峰值24 min。利用变分多普勒雷达分析系统（VDRAS）对这次过程的三维风场进了反演,据此对单体合并期间闪电增强的动力原因进行了研究。根据VDRAS反演的动力场来看,对流云单体合并主要发生在低层辐合区内,合并后上升运动加强,上升气流范围变大,闪电活动显著增强,并主要发生在具有较强垂直风切变的区域,少部分闪电发生在对流区后部开始出现下沉气流的区域。 相似文献
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石家庄地区反射率因子垂直廓线特征分析 总被引：2，自引：1，他引：1
利用自动雨量计数据整理成的10 min一次的雨量资料和s波段多普勒天气雷达体积扫描强度数据,对石家庄地区2004～2007年4次天气过程的实时雷达反射率因子垂直廓线的特征进行了分析.结果表明:层状云和混合性降水反射率因子垂直廓线有明显的零度层亮带;短时强降水过程的反射率因子垂直廓线不存在零度层亮带.冰雹过程中反射率凼子垂直廓线变化较大,降雹前反射率因子的极大值在中上层,降雹发生时反射率因子的极大值高度下降,降雹后反射率因子的极大值减弱.降雪过程的反射率因子垂直廓线零度层亮带不明显.在石家庄西部山区,由于零度层亮带的影响.对层状云和混合性降水回波强度和降水量估计偏高.对短时强降水过程的地面降水估计用反射率因子垂直廓线的方法比最低仰角法更加准确,在均匀性降水中可较好地改善地面雨量估算结果,有利于在山区和无雨量计的地区判断强对流天气的发生、发展和估算降水量的大小. 相似文献
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X波段双偏振多普勒天气雷达降雨估算试验 总被引：8，自引：4，他引：4
用X波段双偏振多普勒天气雷达和RG3-M型自动采集翻斗式雨量计,经过严格科学设计,在平凉野外布置试验场,采用与天气系统移动方向一致的两次层积云资料,验证X波段双偏振多普勒天气雷达的测雨能力。试验表明:雷达原始数据滤波处理的好坏直接影响降雨估算精度的高低,特别是对R(Kdp)和R(Kdp,Zdr)影响明显,滤波后数据点的空间平滑是必要的;发展了用雨量计反演雷达测雨参数方法,此方法改进了不同地区、不同雨滴谱分布情况下雷达定量测雨能力;同时表明X波段雷达受降雨衰减的影响比较严重,这些试验结果可作为下一代测雨天气雷达的重要参考依据。 相似文献
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《Journal of Meteorological Research》2021,(2):329-342
Radar data, which have incomparably high temporal and spatial resolution, and lightning data, which are great indicators of severe convection, have been used to improve the initial field and increase the accuracies of nowcasting and short-term forecasting. Physical initialization combined with the three-dimensional variational data assimilation method(PI3 DVar_rh) is used in this study to assimilate two kinds of observation data simultaneously, in which radar data are dominant and lightning data are introduced as constraint conditions. In this way, the advantages of dual observations are adopted. To verify the effect of assimilating radar and lightning data using the PI3 DVar_rh method, a severe convective activity that occurred on 5 June 2009 is utilized, and five assimilation experiments are designed based on the Weather Research and Forecasting(WRF) model. The assimilation of radar and lightning data results in moister conditions below cloud top, where severe convection occurs; thus, wet forecasts are generated in this study.The results show that the control experiment has poor prediction accuracy. Radar data assimilation using the PI3 DVar_rh method improves the location prediction of reflectivity and precipitation, especially in the last 3-h prediction, although the reflectivity and precipitation are notably overestimated. The introduction of lightning data effectively thins the radar data, reduces the overestimates in radar data assimilation, and results in better spatial pattern and intensity predictions. The predicted graupel mixing ratio is closer to the distribution of the observed lightning,which can provide more accurate lightning warning information. 相似文献
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基于新一代天气雷达的宁德市人工增雨指挥系统 总被引：1，自引：0，他引：1
建立以新一代天气雷达为主的包括卫星、闪电、探空及稠密地面雨量站网的人工增雨技术监测网络,是气象事业现代化建设的任务之一。利用雷达的1 h降水量、回波高度、垂直积分液态水含量等资料,结合天气形势,大气层结状况等因子,采用Visual Basic语言研制人工增雨作业指挥系统。其主要功能包括干旱历史监测、作业条件分析、指挥决策、雷达现场跟踪及效果评估。实践表明,综合考虑回波强度、云顶高度、云中水汽含量、大气层结条件和有利的天气形势,对提高人工增雨作业效果具有积极的意义。 相似文献
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用雷达反演资料诊断江苏地区一次暴雨过程 总被引：1，自引：1，他引：0
对2010年7月12日发生在江苏中部地区一次暴雨天气过程产生的原因、多普勒雷达图像产品特征及由雷达数据反演的物理量场进行了诊断分析和定量评估,得出如下结论:雷达径向速度图像特征变化反映了风场辐合辐散特征的变化,有助于了解雨势增减情况。多普勒雷达径向速度提取的散度数据与NCEP散度数据整体趋势上是一致的,但辐合辐散中心区位置及强度存在差别,雷达反演散度强度较NCEP大4~5倍,天气过程变化期间两者散度在垂直高度场的配置调整均能反映降水动力场变化;400hPa及以下高度反演的平均散度更可信;对于雨强小于等于16mm/h的降水天气过程效果更好。由雷达基数据定量计算得到的平均散度特征和垂直速度随时间和高度的变化,能较好的反映出强降水过程的动力学特性;雷电频次与强降水出现时次有一定相关性,约有1~2h提前量,雷电发生随时间演变与雷达回波强度时空分布较为吻合,云底动能施力参量一定程度可以描述闪电增长情况,较降雨量约有40min左右的提前量,有一定预警能力。 相似文献
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Some aspects of the correlation between lightning and rain activities in thunderstorms 总被引：1，自引：0，他引：1
The lightning activity of convective systems is a sometimes fruitful indicator of their precipitation production. The present study compares rain volume with different types of lightning activity in several convective systems. The study uses data obtained in the Paris area where two lightning detection systems coexist. The Météorage network provides the location and the polarity of cloud-to-ground flashes, while the SAFIR system detects the total flash activity: cloud-to-ground, intra-cloud flashes and VHF individual sources within a given time window. The overall spatial correlation between rain and lightning appears to be very consistent for all lightning types. A pixel-to-pixel study shows that positive CG flashes are associated with higher rainwater volume than negative flashes. Introducing a weight coefficient for positive CG flashes considerably improves the correlation between rain amount and lightning production. Taking into account the specific contribution of each type of lightning flash, the amount of rain can be estimated from the total electrical activity of each system. Comparison with the amount derived from radar measurement shows reasonable agreement. Finally, the parallel time evolutions of rain and lightning rates display quite similar characteristics. 相似文献
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基于多普勒天气雷达、区域气象观测站、常规观测和NCEP再分析数据等,利用三维雷达拼图技术对2018年第18号台风“温比亚”造成的山东暴雨中尺度特征进行分析。研究表明：台风“温比亚”造成的山东暴雨,不同阶段雨强特征有较大差异,长时间强降雨是造成灾害性暴雨的主要因素;此次台风暴雨雨团具有很强的移动特征,是否形成“列车效应”是造成灾害性暴雨的重要因素;雷达三维拼图数据可以清晰识别和分析暴雨过程中尺度雨团的移动、合并和发展规律,这些对准确监测预报暴雨的发生至关重要。 相似文献
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江西省地闪气候特征及其活动强弱评价方法探讨 总被引：1，自引：0，他引：1
为科学评价雷电活动强弱和为雷电预报的效果检验提供参考依据,基于2003—2010年江西省闪电监测定位系统资料,分析了逐小时的闪电频数变化,发现0.01°×0.01°经/纬度分辨率格点上的地闪频数最大值出现在2004年9月18日17:00—18:00,为64次/h;相较其他时段而言,16:00—17:00闪电活动最强。基于地闪观测资料、探空及多普勒雷达资料,分析了雷达回波强度与地闪数的相关性统计特征发现,在0.1°×0.1°经纬度网格点上,0℃层以上最大回波强度大值与相应时段内的地闪频数大值常不一一对应,但地闪频数大值多出现在强回波附近。格点上的12 min内的地闪数大都≤60个,以1—20个为最多;地闪数≥40个的格点数则明显减少;对应的0℃层以上最大回波强度集中于35—60 dBz,回波强度≤35 dBz或≥60 dBz的格点数则明显偏少。回波强度介于45—55 dBz的格点数明显大于回波强度>55 dBz以及<45 dBz的格点数,表明这个区间内的闪电活动最强。因此,借助0℃以上最大回波强度可简单地区分闪电活动强弱。 相似文献
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上海地区几类强降水雨滴谱特征分析 总被引：3，自引：3，他引：0
用Parsivel激光降水粒子谱仪资料对2013年上海地区4—10月份期间4种类型 (层状云、对流暖云主导型、对流冷云主导型和强台风影响下的混合暖云型) 降水过程的雨滴谱特征进行了分析。通过平均雨滴谱及其拟合特征、雨滴数密度与含水量分布、雨滴尺度与速度二维谱分布等对比分析发现:各类降水中, 雨滴谱的峰值结构与雨强大小有关, 其中直径介于0.187~1.312 mm的小雨滴均出现峰值且总数最多。各尺度雨滴数密度及其比例决定了其降水量贡献比, 在冷云强降水中的雨强贡献最大的雨滴尺度要显著大于其他3种类型。雨滴谱宽按大小排列依次为对流冷云主导型、混合暖云型、对流暖云主导型和层状云。最后综合运用雨滴谱、雷达、雨量站、闪电等观测资料对9月13日对流冷云主导型降水过程进行分析后发现:在雷暴的演变过程中, 雨滴谱特征与雷达反射率因子、垂直液态水含量、自动站雨强、闪电频次等要素均有较好的相关性。冷云产生的冰晶和冰雹融化后的大雨滴进入中低层的广谱小雨滴群, 并通过破碎分裂增加了大雨滴的形成概率, 尤其是捕捉碰并过程更加快了大雨滴的增长速度, 使雨强在短时间内迅速加强。雨滴谱中各档粒子数的演变, 揭示了降水强度的变化, 用雨滴谱资料可有效弥补现有雷达定量估测降水的偏差, 且在冷云中改善明显。 相似文献
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用Micaps和NCEP再分析资料对2012年7月3日发生在淮河以南地区的大范围强雷暴天气进行了分析,得出高、低空急流配置,形成低空辐合,高空辐散,槽线由高到低前倾,有利增强大气不稳定层结,中尺度切变线南北摆动具有触发对流作用等,为该区强雷暴多灾种天气的发生,提供了动力和热力条件。从云图、雷达参数和地闪特征对比分析得出冰雹、雷击、强降水,分别发生在强对流云团发展的不同时间和不同部位。其云团的形态、强度和范围等也不同。冰雹所表现出的回波强度、回波顶高和垂直积分液态水含量为最强,雷击次之,强降水最弱。在地闪出现的各个阶段都有可能出现雷击事故,但多为负地闪,强度均较强。强降水过程多为负地闪,强度较弱,降水集中时段,地闪频次高。冰雹发生时地闪频数明显下降,且多为正闪。雷击过程强度和陡度变化最平缓,冰雹过程突变最明显。雷击发生在整个地闪过程中强度和陡度都相对较大的时刻;冰雹发生前约半小时有强度和陡度的骤增;强降水阶段地闪平均强度和陡度都最小。 相似文献
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利用雷州半岛2007年7、8月常规地面气象观测资料和闪电定位资料,分析了闪电活动与24 h降水量及雨强的关系,结果表明:雷州半岛盛夏地闪频数的最大值中心在其东侧海面上,地闪高发带沿海岸线呈南北向分布;地闪频次存在明显的日变化特征,13:00～18:00为闪电高发时段;无闪电时,有41.3%的降水事件24 h降水量≤1 mm,61.5%的降水事件雨强≤1 mm·h-1;有闪电时相应的事件概率分别为25.9%和37.7%;24 h降水量>30 mm的事件大多发生在有闪电的情况下,无闪电时极少发生;雨强概率分布的日变化特征不明显;有闪电活动时,雨强均值变化幅度加大. 相似文献
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在雷达反射率数据定量应用中,标定误差是导致结果产生偏差的重要原因之一。星载雷达（TRMM PR）长期工作的稳定性和连续性已被验证,本文将星载雷达数据转换到S波段,通过对比星载雷达和南京雷达同时段不同高度（相对于融化层的位置）不同降水类型（层云降水或对流降水）的数据,得到两部雷达对融化层以下层云降水的观测相关性高,差异稳定。通过对比分析星载雷达和南京雷达同时段零度层以下层状云降水的观测数据,得出两部雷达反射率因子值的回归关系式。以星载雷达观测数据为基准,使用该关系式对南京雷达反射率数据进行订正,并通过雨量计数据对订正结果进行验证,结果显示使用本文订正关系式订正后雷达估计的降雨量更接近雨量计的观测值。 相似文献
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利用贵州省三维闪电定位资料、C波段Doppler天气雷达资料及探空资料对2017年贵州一次强天气过程中闪电特征及雷达回波特征的相关性进行分析。结果表明：回波顶高与闪电频数的相关性优于回波强度与闪电频次的相关性;不同温度层上,大于等于30dBz的回波面积与总闪频次和负地闪频次相关性都比较好,其中零度层高度上大于等于30dBz的回波面积与总闪频次相关性最好,且多项式拟合效果优于线性拟合;最大回波强度 、回波顶高 以及30dBz强度回波发展高度对闪电的发生具有一定的指示意义。 相似文献
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A cloud-resolving study on the role of cumulus merger in MCS with heavy precipitation 总被引：4，自引：0，他引：4
The cumulus merging processes in generating the mesoscale convective system （MCS） on 23 August 2001 in the Beijing region are studied by using a cloud-resolving mesoscale model of MM5. The results suggest that the merger processes occurred among isolated convective cells formed in high mountain region during southerly moving process play critical role in forming MCS and severe precipitating weather events such as hailfall, heavy rain, downburst and high-frequency lightning in the region. The formation of the MCS experiences multi-scale merging processes from single-cell scale merging to cloud cluster-scale merging, and high core merging. The merger process can apparently alter cloud dynamical and microphysical properties through enhancing both low- and middle-level forcing. Also, lightning flash rates are enhanced by the production of more intense and deeper convective cells by the merger process, especially by which, the more graupel-like ice particles are formed in clouds. The explosive convective development and the late peak lightning flash rate can be found during merging process. 相似文献