摘要
利用常规、加密自动气象站以及NCEP1°×1°再分析资料,对北京"7.21"特大暴雨过程天气特征和环境条件进行了初步分析。结果表明:1)降水过程由锋前暖区和锋面降水组成。暖区降水持续时间长,小时雨量大,具有典型的"列车效应",是造成特大暴雨的主要降水过程。2)中高层低涡东移、副热带高压北抬、中低层低涡暖式切变线影响是暴雨主要形势特征,暴雨发生在低层低涡右前部暖式切变和高空强辐散气流下方。3)暴雨过程开始前对流层中低层存在双层湿暖盖。位势不稳定层结的建立机制主要与低层增湿和中层变干的湿度差动平流有关,而低层增湿和中层变干过程与中低层风向转变相关联。4)暴雨发生前0—6 h对流层整层不断增湿,且对流层中高层比低层增湿效应更加明显。与普通暴雨增湿过程和水汽主要集中在对流层中下层不同,深厚的湿度层次,较低的凝结高度和自由对流高度是其显著特征。
The weather characteristics and environment conditions of a torrential rain occurred in Beijing on 21 July 2012 have been investi- gated by using conventional observation data, intensive automatic weather station observations and 1°×1°NCEP reanalysis data. The conclu- sions are as follows. 1） The rain event consists of convective and frontal precipitation. The convective precipitation, which has longer rainfall time and higher rainfall intensity, was the main rainfall process during the torrential rain. 2） The primary atmospheric circulation characteris- tics are a east-moving vortex in mid-high level, a north-moving subtropical high and a sharp vorticity wind shear. The rainfall ocemwed on the low-level sharp wind shear and under the high-level divergence. 3） There were two warm-moist layers in low-level before the heavy rain started. The establishment of the potential instability was mainly related to the wetter low-level and the drier mid-high-level, which was re- suhed by the change of the wind direction between low and high level. 4） This torrential rain occurred and developed in the whole troposphere layer, and the mid-high level was wetter than low-level. Unlike normal rainfall, the features of deep moist layer, the low condensation level and low free convection level were evident in this ease.
出处
《暴雨灾害》
2013年第3期210-217,共8页
Torrential Rain and Disasters
基金
中国气象科学研究院灾害天气国家重点实验室开放课题(2012lasw-B07LASW)
关键词
特大暴雨
暖区降水
列车效应
层结与水汽条件分析
torrential rain
convective precipitation
train effect
stratification and water vapor condition analysis
