摘要
利用1971-2019年大连地区6个气象台站的降水资料,NCEP/NCAR逐月高度场、风场、气压场和水汽场等再分析资料,以及国家气候中心整编的130项气候系统监测指数资料,采用合成和相关分析等统计诊断方法,对比分析了大连地区7月降水偏多和偏少年对应的大气环流异常特征,并在此基础上诊断分析2018年7月大连地区降水异常偏少的事实和成因。结果表明:2018年7月大连地区处于降水偏少的气候背景,是1971年以来降水最少的时期。500 h Pa位势高度场上30°-50°N的东亚大陆位势高度偏高,东亚沿岸由南至北为"负-正-负"的高度距平分布,中国华北-中国东北-日本海为位势高度正距平,东亚大槽偏东和偏弱,西太平洋副热带高压强度偏强,脊线和北界位置异常偏北,是历史同期最偏北的年份,深厚暖性高压影响大连地区,且稳定维持,从而引起该地区持续受异常下沉运动控制;同时850 h Pa菲律宾附近至日本以南地区维持异常的气旋式环流,并且整层处于水汽通量异常辐散区域,不利于水汽汇合形成降水。以上是造成大连地区降水异常偏少的主要原因。其中,西太平洋副高强度偏强、脊线和北界位置异常偏北对大连地区降水异常偏少起了关键作用。
Based on the daily precipitation data observed by six meteorological stations in the Dalian region from 1971 to 2019,the NCEP/NCAR( National Centers for Environmental Prediction/National Center for Atmospheric Research) data,including monthly height field,wind field,water vapor field and other reanalysis data,and the data from130 climate system monitoring indices compiled by the National Climate Center,the characteristics of anomalous atmospheric circulations with more or less than normal precipitation in July were analyzed using statistical diagnosis methods such as synthesis and correlation analysis. Furthermore,the observation truth and cause of anomalous less precipitation in July of 2018 over the Dalian region were studied. The results show that in July of 2018,the Dalian region is in the climate background with less precipitation. The precipitation in July of 2018 is the least during the same period since 1971. The geopotential height of the East Asia continent at 30°-50°N at 500 hPa is relatively high. From the south to the north along the east Asian coast,it presents a " negative-positive-negative" pattern. The geopotential height from North China-Northeast China-Japan Sea is a positive anomaly. The East Asian trough is easterly and weakly,and the western Pacific subtropical high( WPSH) is stronger. The position of the ridgeline and the northern boundary is abnormally northerly,and it is the most northward year for the same period in history. A deeper and warmer high pressure controls the high and low levels over the Dalian region and its stable maintenance which causes the continuous subsidence motions of airflows. At the same time,a cyclonic circulation of wind anomalies at 850 hPa dominates around the south of Japan and the Philippines,and the anomalous airflow divergence region of water vapor flux occurs in Dalian,so it is not favorable for the water vapor convergence to form precipitation. These are the main reasons for the abnormally less precipitation in the Dalian region,in which the stronger WP
作者
王秀萍
李红斌
张靖萱
WANG Xiu-ping;LI Hong-bin;ZHANG Jing-xuan(Dalian Meteorological Observatory of Liaoning Province,Dalian 116001,China;Dalian Weather Modification Office,Dalian 116001,China;Shenyang Meteorological Service Center,Shenyang 110168,China)
出处
《气象与环境学报》
2021年第2期19-26,共8页
Journal of Meteorology and Environment
基金
辽宁省气象局关键技术项目(LNGJ201901)
辽宁省气象局市县自筹资金科研项目
大连市气象局业务应用开发项目(dlqk201908)共同资助。
关键词
降水异常
大气环流
成因分析
Anomalous precipitation
Atmospheric circulation
Cause analysis
