基于GPM资料的四川盆地及周边地区夏季地形降水垂直结构研究  

The Vertical Structure of Orographic Precipitation during Warm Season in the Sichuan Basin and Its Surrounding Areas by Using GPM Dual-frequency Spaceborne Precipitation Radar

作　　者：沈程锋 李国平[1,2] SHEN Chengfeng;LI Guoping(School of Atmospheric Sciences,Chengdu University of Information Technology,Chengdu 610225,Sichuan,China;Ministry of Education&Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science&Technology,Nanjing 210044,Jiangsu,China)

机构地区：[1]成都信息工程大学大气科学学院,四川成都610225 [2]气象灾害预报预警与评估省部共建协同创新中心,江苏南京210044

出　　处：《高原气象》2022年第6期1532-1543,共12页Plateau Meteorology

基　　金：国家自然科学基金项目(42175002,91937301,42075013);国家重点研发计划项目(2018YFC1507200)。

摘　　要：基于ETOPO1高程资料将四川盆地及其周边区域分为平原、山地、高山三类地形,利用2014-2021年5-9月的GPM DPR资料,对发生在三类地形上的层云和对流性降水事件进行统计,并分析对比不同地形下强降水的垂直结构特征。研究表明:(1)相较于其他雨强等级的降水,平原对流性弱降水的降水粒子在近地层受蒸发作用最为明显,反射率因子波动较大且呈减弱趋势。对流性强降水中,随着地势抬升,反射率因子中心高度也随之升高。(2)对流性强降水中,随着地势升高,因地形作用形成的强上升气流利于雨滴碰并聚合成大雨滴的同时也更易使降水粒子破碎形成小雨滴,从而导致大雨滴(粒子质量加权平均直径Dm≥2.6 mm)出现的概率增大,D_(m)分布域宽度增宽;层云性强降水中,高山冻结层高度以下的中等直径降水粒子(1.4 mm≤D_(m)≤1.65 mm)出现的概率比平原大。(3)对流性强降水中,平原的粒子数浓度参数dBNw高频区的分布较山地和高山更为集中,而层云性强降水的情形正好相反。相较于平原,高山的降水粒子在10 km以上呈现数浓度较低、尺度较大的特征。(4)雷达反射率、D_(m)和dBN_(w)三者之间关联密切。冻结层以下,对流性强降水粒子的D_(m)高频区分布范围与雷达反射率高频区的分布区间高度吻合。对流性强降水的降水粒子在近地面的D_(m)比层云性强降水的大,但其dBN_(w)却比层云性强降水的小。本研究有助于从云微物理过程和降水垂直结构视角深入认识地形对强降水的影响。After dividing the Sichuan Basin and its surrounding areas into three types of terrain,including plains,mountains(500~1500 m above sea level),and high mountains(1500~4000 m above sea level)using ETOPO1 elevation data,this study statistics on convective and stratiform precipitation events over three types of terrain using the Dual-frequency Precipitation Radar(DPR) onboard the Global Precipitation Measurement(GPM)Core Observatory from May to September of 2014-2021 in order to analyze the vertical structure of heavy convective and stratiform precipitation to contrast where the differences they are. The result shows that:(1)The precipitation particles of the light convective precipitation over plains are most significantly affected by evaporation in the near-surface layer that compared with other rain rate,which causes reflectivity factor fluctuates greatly and tends to weaken in surface layer. For heavy convective precipitation events,in addition,the height of the high frequency center of the radar reflectivity factor increases with the increasing elevation.(2)For heavy convective precipitation events,as the terrain rises,the strong updraft formed by the topography facilitates raindrops to collide and aggregate into large raindrops,and it is also easier to break the precipitation particles into small raindrops,which not only causes the occurrence probability of large raindrops(mass-weighted mean diameter,D_(m)≥2. 6 mm)increases but also causes the distribution range of D_(m) widening;For heavy stratiform precipitation events,the occurrence probability of medium-diameter precipitation particles(1. 4 mm≤D_(m)≤1. 65 mm)below the freezing height over high mountains is greater than that over plains.(3)For heavy convective precipitation events,the 10 log10 of the particle number concentration(dBN_(w))high-frequency region over plains is more concentrated than those over mountains and high mountains,while the situation of heavy stratiform precipitation events is just the opposite. In a few words,the precipitation pa

关 键 词：四川盆地及周边 强降水 GPM 双频星载雷达DPR 降水垂直结构 

分 类 号：P426.614[天文地球—大气科学及气象学]