华北地区一次低槽冷锋云系结构和增雨条件研究  

Study on cloud structure and rainfall enhancement condition of a low-trough cold-front cloud over North China

作　　者：史月琴[1,2] 赵俊杰 孙晶[1,2] 孙玉稳[4] SHI Yueqin;ZHAO Junjie;SUN Jing;SUN Yuwen(CMA Cloud-Precipitation Physics and Weather Modification Key Laboratory,Beijing 100081,China;Weather Modification Center of China Meteorological Administration,Beijing 100081,China;Meteorological Disasters Defense Technology Center of Shanxi Province,Taiyuan 030032,China;Hebei Provincial Weather Modification Office,Shijiazhuang 050021,China)

机构地区：[1]中国气象局云降水物理与人工影响天气重点开放实验室,北京100081 [2]中国气象局人工影响天气中心,北京100081 [3]山西省气象灾害防御技术中心,山西太原030032 [4]河北省人工影响天气办公室,河北石家庄050021

出　　处：《干旱气象》2022年第6期1003-1013,共11页Journal of Arid Meteorology

基　　金：国家重点研发计划课题“新一代人影数值模式系统研发”(2018YFC1507901);河北省“十三五”气象重点项目——云水资源开发利用工程的示范项目“太行山东麓人工增雨防雹作业技术试验”(HBRYWCSY-2017);西北区域人工影响天气能力建设项目研究试验“西北区域中尺度人影模式同化系统研制和应用”(RYSY201908)共同资助。

摘　　要：地处华北地区的河北、山西等地2017年春季发生较严重干旱,对农作物播种及生长造成一定影响,开展人工增雨作业有利于缓解旱情、减轻旱灾影响。为科学、精准地开展人工增雨作业,利用云降水显式预报系统(Cloud and Precipitation Explicit Forecast System,CPEFS_v1.0)结合实况资料,对2017年5月22—23日发生在华北地区的一次典型低槽冷锋云系降水过程进行研究,选择河北邢台站为代表研究不同降水阶段云系结构和增雨条件。结果表明,当邢台处于地面冷锋之后、700 hPa槽前时,因锋面抬升出现较强降雨,10 min雨量最大超过2.0 mm,此阶段850 hPa以下水汽通量大于21 g·hPa^(-1)·cm^(-1)·s^(-1),随着云砧移过邢台,云系由冰雪晶组成的高层冷云转变为冷暖混合云,低层云水、中层过冷水和霰的混合比均明显较高,霰的融化、雨滴碰并云滴是降雨形成的主要过程;当邢台处于700 hPa槽后、500 hPa槽前时,降水转变为由深厚层云形成的小雨,此阶段中低层水汽、云水含量明显减小,上升运动主要出现在冷区且明显减弱,云系依旧为冷暖混合云,但过冷水及霰的含量降低,降水主要由霰的融化产生;500 hPa高空槽过境之后降水逐渐消散。增雨可播时间主要出现在锋面抬升强雨期、深厚层云小雨期,可播高度位于4.0~7.9 km,强可播区在4.0~5.5 km高度且含有充沛过冷水的区域。Hebei,Shanxi provinces in North China suffered from severe drought in the spring of 2017.The drought had a certain im⁃pact on crop sowing and growth.Cloud seeding is helpful to alleviate drought.To carry out cloud seeding scientifically and accurately,based on the Cloud and Precipitation Explicit Forecast System(CPEFS_v1.0)and observational data,a typical low-trough cold-front cloud system precipitation process that occurred in North China from May 22 to 23,2017,is studied.Choosing the Xingtai station in Hebei Province for an example,the cloud system structure at different precipitation stages and cloud seeding conditions are explored.The results show that when Xingtai is located behind the ground cold front and in front of the 700 hPa trough,strong rainfall occurs due to uplift of the front.The maximum rainfall in 10 minutes exceeds 2.0 mm,and the water vapor flux below 850 hPa at this stage is greater than 21 g·hPa^(-1)·cm^(-1)·s^(-1).As the cloud anvil moves over Xingtai,the high-level cold cloud composed of ice and snow crystals transforms into a cold-warm mixed cloud.The mixing ratio of low-level cloud water,middle-level supercooled water and graupel is sig⁃nificantly higher.The main process of rainfall formation includes the collision of raindrops and cloud droplets,the melting of graupel.When Xingtai is located behind the 700 hPa trough and in front of the 500 hPa trough,the precipitation transforms into light rain formed by deep stratus clouds.The content of water vapor and cloud water in the middle and low layers decreases apparently at this stage.The rising movement mainly appears in the cold area and weakens obviously.The cloud system is still a mixed cold-warm cloud,but the mixing ratio of supercooled water and graupel decreases.The precipitation is mainly produced by the melting of graupel.The precipitation gradually dissipates after the 500 hPa trough transits.The cloud seeding time mainly occurs in the frontal uplifting-heavy rain period and the deep stratus cloud-light rain period.The seedi

关 键 词：低槽冷锋 云系结构 增雨条件 数值模拟 邢台 

分 类 号：P481[天文地球—大气科学及气象学]