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| 1 | A Possible Dynamic Mechanism for Rapid Production of the Extreme Hourly Rainfall in Zhengzhou City on 20 July 2021显示文摘In this study,the unprecedented extreme rainfall event during 19-20 July 2021,which caused devastating flooding in Zhengzhou City and its nearby areas,is examined based on observational data analysis and WRF model 40-h simulations on 1-km horizontal resolution.The results show that the model successfully reproduces(i)major synopticscale weather systems(i.e.,the western Pacific subtropical high,the Tibetan high,two typhoons,and the Huang-Huai cyclone),(ii)convective initiation along the east to north edge of the Songshan Mountain,where orographic lifting is obvious,and(iii)subsequent formation of the convective storm producing the extreme rainfall in Zhengzhou.In particular,the model generates the maximum rainfall rate of 233 mm h^(-1)and 40-h accumulated rainfall of 704 mm,corresponding well to the observed extreme values of 201.9 mm h^(-1)and 818 mm,at nearly observed timing and location.Importantly,the model reproduces an intense quasi-stationary,well-organized meso-γ-scale convective system,surrounded by an arc-shaped convergence zone,allowing the development of convective updrafts in a three-quarter circle around the convective system,in a way similar to“multidirectional pumping,”attracting all associated precipitation overlaid and concentrated into the same trailing region to generate the extreme hourly rainfall over Zhengzhou.Our study emphasizes the significant contribution of the unique dynamic structure of the well-organized meso-γ-scale convective system to the record-high hourly rainfall.A possible dynamic mechanism for short-time extreme rainfall production is proposed.That is,the arc-shaped convergence zone of the mesoscale convective system,acting like multidirectional lifting pumps,transports precipitation from different directions into the same region,and thus produces the extreme rainfall.The results gained herein may shed new light on better understanding and forecasting of short-time extreme rainfall. | Jinfang YIN Haodong GU Xudong LIANG Miao YU Jisong SUN Yanxin XIE Feng LI Chong WU | 2022 | Journal of Meteorological Research2022，36，1： | 17 |
| 2 | 华南前汛期强降水个例模式降水预报误差成因初探显示文摘2015年5月19—20日,华南出现一次暴雨过程。检验表明欧洲中期天气预报中心全球确定性预报模式(以下简称EC模式)预报的20日强降水落区在广东境内较实况明显偏北,高估了天气尺度系统附近的降水强度,漏报了其南侧暖区内中尺度对流系统(mesoscale convective system,MCS)造成的降水,华东中尺度模式预报明显优于EC模式。利用高分辨率中尺度天气研究预报模式(以下简称WRF模式)对该暴雨过程进行了模拟,对比EC模式降水物理过程,初步探索了EC模式降水预报误差的成因,结果表明:20日位于广东暖区内的对流组织发展成MCS,并造成明显的低层冷池出流和中高层潜热加热,二者共同作用使得中低层气旋式环流在广东中东部发展,配合其南侧的强西南风水汽输送,在气旋式切变附近不断触发新的对流并南移使得广东中南部暖区内出现强降水,WRF模式能较好地模拟出该过程,而EC模式未能预报出暖区对流及其反馈,从而导致其漏报了广东中南部的强降水;EC模式预报的降水与天气尺度环流之间的正反馈进一步加大了降水的预报偏差。EC模式预报的20日白天的强降水主要位于华南北部切变线附近,且以层状云降水为主,降水产生的潜热使得对流层低层切变线附近减压更明显,预报的切变线辐合较分析场明显偏强,使得其预报的切变线附近降水较实况偏强。 | 胡宁 符娇兰 汪会 | 2020 | 气象2020，46，8： | 10 |
| 3 | Understanding the dynamical-microphysical-electrical processes associated with severe thunderstorms over the Beijing metropolitan region显示文摘The Dynamical-microphysical-electrical Processes in Severe Thunderstorms and Lightning Hazards(STORM973)project conducted coordinated comprehensive field observations of thunderstorms in the Beijing metropolitan region(BMR)during the warm season from 2014 to 2018.The aim of the project was to understand how dynamical,microphysical and electrical processes interact in severe thunderstorms in the BMR,and how to assimilate lightning data in numerical weather prediction models to improve severe thunderstorm forecasts.The platforms used in the field campaign included the Beijing Lightning Network(BLNET,consisting of 16 stations),2 X-band dual linear polarimetric Doppler radars,and 4 laser raindrop spectrometers.The collaboration also made use of the China Meteorological Administration’s mesoscale meteorological observation network in the Beijing-Tianjin-Hebei region.Although diverse thunderstorm types were documented,it was found that squall lines and multicell storms were the two major categories of severe thunderstorms with frequent lightning activity and extreme rainfall or unexpected local short-duration heavy rainfall resulting in inundations in the central urban area,influenced by the terrain and environmental conditions.The flash density maximums were found in eastern Changping District,central and eastern Shunyi District,and the central urban area of Beijing,suggesting that the urban heat island effect has a crucial role in the intensification of thunderstorms over Beijing.In addition,the flash rate associated with super thunderstorms can reach hundreds of flashes per minute in the central city regions.The super(5%of the total),strong(35%),and weak(60%)thunderstorms contributed about 37%,56%,and 7%to the total flashes in the BMR,respectively.Owing to the close connection between lightning activity and the thermodynamic and microphysical characteristics of the thunderstorms,the lightning flash rate can be used as an indicator of severe weather events,such as hail and short-duration heavy rainfall.Lightning data can also be assimilated into numerical weather prediction models to help improve the forecasting of severe convection and precipitation at the cloud-resolved scale,through adjusting or correcting the thermodynamic and microphysical parameters of the model. | Xiushu QIE Shanfeng YUAN Zhixiong CHEN Dongfeng WANG Dongxia LIU Mengyu SUN Zhuling SUN Abhay SRIVASTAVA Hongbo ZHANG Jingyu LU Hui XIAO Yongheng BI Liang FENG Ye TIAN Yan XU Rubin JIANG Mingyuan LIU Xian XIAO Shu DUAN Debin SU Chengyun SUN Wenjing XU Yijun ZHANG Gaopeng LU Da-Lin ZHANG Yan YIN Ye YU | 2021 | Science China Earth Sciences2021，64，1： | 1 |
| 4 | 冬奥会延庆赛区降雪与边界层东风的关系显示文摘受特殊地理环境影响,北京地区冬季降雪常与边界层东风相伴,边界层东风所引起的水汽输送和动力辐合效应对降雪发生发展有重要意义。不同于已有边界层东风对平原地区降雪影响的研究,本文结合2022年冬奥会北京延庆赛区的地形特征,对比相似天气背景下不同温湿特性、不同发展高度的边界层东风对降雪的作用机制,研究表明:(1)途经渤海湾的路径较长有利于边界层东风的明显增湿,反之增湿效果则较弱;(2)'干冷'性质的偏东风可形成冷垫抬升北京平原及低海拔地区的暖湿空气;当偏东风在垂直方向发展较为深厚(600 m以上)时,能够翻越延庆东部海拔较低的军都山并在背风坡形成绕流汇合,同时受西部海拔较高的海陀山阻挡,形成迎风坡的强迫抬升,二者共同作用导致延庆区的辐合东强西弱,进而造成降雪分布呈东多西少的特征;(3)'暖湿'性质的边界层东风因垂直延展高度较低,无法向西越过军都山,对延庆赛区降雪基本无影响;(4)空中500 hPa为西北气流影响时,除考虑边界层东风能否越山之外,若存在与地形高度接近的、700 hPa高度附近饱和区与抬升运动的有利配合,将导致延庆赛区的高海拔山区出现明显降雪。 | 于波 李桑 郝翠 刘郁珏 杜佳 卢俐 | 2022 | 大气科学2022，46，1： | 1 |
| 5 | 利用双偏振参量估计降水粒子下落末速度及三维风场反演的应用显示文摘降水系统三维风场反演的关键问题之一是准确地估算降水粒子下落末速度(W_(t)),为了探究双偏振雷达估计W_(t)的能力,利用广东省龙门地区的雨滴谱数据,建立了W_(t)与S和X波段双偏振雷达观测量的关系,并且将其应用于广州和韶关两部雷达的风场反演。对华南地区2019年4月发生的一次飑线过程进行风场反演试验,分析讨论了此次飑线过程的风场结构配置,并探索了利用不同方法估算的W_(t)在反演出的风场结构上的差异。结果表明:S和X波段雷达通过回波强度(Z H)和差分反射率(Z DR)估算W_(t),其函数形式为幂函数和一次函数,通过Z DR估算的W_(t)均方根误差相较利用Z H估算的W_(t)均方根误差更小、相关系数更大,因此通过Z DR估算的W_(t)的效果更好。此次飑线过程主要从西北向东南方向发展,风场主要是西风和西南风,在飑线前部弓状回波区域内存在明显的辐合区,垂直结构是低层辐合、高层辐散。对比利用不同方法估算W_(t)得到的三维风场,其水平风场变化主要集中在±1 m·s^(-1)的范围,水平经向风速的变化(Δu)主要是正值,水平纬向风速的变化(Δv)主要是负值,垂直方向上风速的变化(Δw)集中在±0.15 m·s^(-1)内,主要是正值,低层Δu、Δv、Δw较高层小。研究结果为降水系统三维风场反演及垂直速度反演提供了参考依据。 | 杨华 李瑞义 刘黎平 郑佳锋 王浩宇 | 2023 | 气象2023，49，7： | 0 |
| 6 | Identification of synoptic patterns for extreme rainfall events associated with landfalling typhoons in China during 1960–2020显示文摘Extreme rainfall associated with landfalling typhoon(ERLTC)can cause severe disasters and economic impacts throughout China.Improving the accuracy of ERLTC forecasts is therefore crucial in disaster prevention and mitigation.The top 26 ERLTC events in China during 1960–2020 are investigated based on multi-source datasets.These ERLTC events are categorized into five main types according to the geographical location of the extreme precipitation and its position relative to the tropical cyclone(TC)center,namely:the typhoon inner-core rainfall in Taiwan(TWIC),typhoon inverted trough rainfall in Taiwan(TWIT),weak typhoon rainfall in Hainan(HNWK),strong typhoon rainfall in Zhejiang(ZJST)and inland typhoon remnant rainfall(ILRM).All the ERLTC events occurred in the weakening stage of TC after reaching its lifetime maximum intensity in convective cloud(TBB≤−32℃)regions over complex local terrain.The translational speeds of 20 TCs(76.9%of the total)were smaller than the climatological average(20.6 km h^(−1))during the extreme precipitation events.The differences are as follows:the TWIC and TWIT types are featured with different season,track and water vapor channel although both occurred in Taiwan.The other three types are distinguished by spinning track and strong convective cloud for HNWK type,strong TC intensity and binary TC interactions for ZJST type;and stagnation and strong westerly trough activity for ILRM type,respectively.These results are expected to provide useful clues for an in-depth understanding of ERLTC events over China. | Da-Jun ZHAO Hong-Xiong XU Yu-Bin YU Lian-Shou CHEN | 2022 | Advances in Climate Change Research2022，13，5： | 0 |
| 7 | Impacts of Increasing Model Resolutions and Shortening Forecast Lead Times on QPFs in South China During the Rainy Season显示文摘This study investigated the impacts of increasing model resolutions and shortening forecast lead times on the quantitative precipitation forecast(QPF)for heavy-rainfall events over south China during the rainy seasons in 2013-2020.The control experiment,where the analysis-forecast cycles run with model resolutions of about 3 km,was compared to a lower-resolution experiment with model resolutions of about 9 km,and a longer-term experiment activated 12 hours earlier.Rainfall forecasting in the presummer rainy season was significantly improved by improving model resolutions,with more improvements in cases with stronger synoptic-scale forcings.This is partially attributed to the improved initial conditions(ICs)and subsequent forecasts for low-level jets(LLJs).Forecasts of heavy rainfall induced by landfalling tropical cyclones(TCs)benefited from increasing model resolutions in the first 6 hours.Forecast improvements in rainfall due to shortening forecast lead times were more significant at earlier(1-6 h)and later(7-12 h)lead times for cases with stronger and weaker synoptic-scale forcings,respectively,due to the area-and case-dependent improvements in ICs for nonprecipitation variables.Specifically,significant improvements mainly presented over the northern South China Sea for low-level onshore wind of weak-forcing cases but over south China for LLJs of strong-forcing cases during the presummer rainy season,and over south China for all the nonprecipitation variables above the surface during the TC season.However,some disadvantages of higher-resolution and shorter-term forecasts in QPFs highlight the importance of developing ensemble forecasting with proper IC perturbations,which include the complementary advantages of lower-resolution and longer-term forecasts. | 张旭斌 李静珊 罗亚丽 宝兴华 陈靖扬 肖辉 文秋实 | 2023 | Journal of Tropical Meteorology2023，29，3： | 0 |
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