摘要
为了了解珠江三角洲(简称珠三角)地区重大短时强降水(小时雨强≥50 mm)发生的环境特征,利用珠三角地区稠密自动气象站资料、探空资料、卫星资料等分析研究了近7年(2007—2013年)68个重大短时强降水事件的环境流型、T-lnp图形态和关键物理参数,结果表明珠三角地区重大短时强降水天气流型主要有台风型、西南季风型、北部湾低压型、冷(式)切变线型和热带云团型等5种;不同类型、不同季节出现的频率不同。台风型、西南季风型和北部湾低压型的大多数过程T-lnp图温度廓线和湿绝热线很接近,整层水汽含量丰富,对流有效位能(CAPE)大致呈"瘦弱"的狭长形形态;冷(式)切变线型温湿廓线呈上干下湿分布,CAPE大致呈较"胖"的狭长形;热带云团型温度廓线和湿绝热线很接近,CAPE形态较"胖"。850~500 hPa间温差△T_(85)都较小,一般在21~23℃,大气层结接近于湿中性层结,呈现弱的条件不稳定层结,表明大多数过程中有利于重大短时强降水发生的环境条件的关键点不是强对流预报中常关注的"高空冷空气的侵入",而是低层暖湿气流的输送;地面露点一般在23~25℃,暖云厚度在4100 m以上;大多数重大短时强降水发生前大气可降水量都在57 mm以上,其中台风型最大,其次是西南季风型、北部湾低压型、热带云团型,冷(式)切变线型最小,台风型、西南季风型、北部湾低压型CAPE一般小于1500 J·kg^1,属于比较温和的CAPE值,冷(式)切变线型、热带云团型平均CAPE≥1700 J·kg^(-1);对于所有类型对流抑制能(CIN)≤50 J·kg^1;除热带云团型外,大多数过程出现了低空急流;五种流型配置下,台风型、西南季风型大多处在弱到中等的0~6 km深层垂直风切变环境中,北部湾低压型和热带云团型处在弱的0~6 km垂直风切变环境中;冷(式)切变线型大多数过程处在中等强度的0~6 km垂直风切变环境中。可以将流型配置方法(分型)、重大短时强降水对应的关键环境参数以及根据箱线图展示的参数范围设定适宜的阈值的方法相结合,为珠三角地区显著强降水预报的改进提供有价值的参考。
In order to understand the environmental characteristics of short-time severe rainfall event （hourly rainfall amount ≥50 mm） in Pearl River Delta, we researched the weather flow, T-lnp chartpatterns and key physical parameters of 68 short-time intense rain event for nearly 7 years （2007--2013） by using automatic weather station data, sounding data, satellite data in the Pearl River Delta region. The results showed that such severe rainfalls in Pearl River Delta are characterized by, first, the weather flow patterns, which include typhoon type, southwest monsoon type, Beibu Gulf low pressure type, cold shear line type and tropical cloud type. Different types have different frequencies in different seasons. Secondly, temperature profiles and wet adiabat are very close in T-lnp in most of the short-time severe rain events, and the water vapor content are rich in the whole layer. Thirdly, the features of the key parameters of the severe rainfalls are that mainly the value of T850-T500 is small, usually 21--23℃ with a weak unstable stratification, higher ground dew point and PW. CAPE values are more moderate, mostly less than 1500 J · kg-1. CIN and vertical wind shear of 0--6 km are relatively weak, and low-level jets appear in most ca- ses. The key conditions for most of the short-time severe rainfall process are not the high-altitude cold air intrusion, but the warm air transport from low level. Although small CAPE value limits updraft, the cloud base of specific humidity is high. If combining the configuration method of flow pattern （type）, the key environmental parameters, the range of parameters to set appropriate threshold according to the box whisker plots, we can provide valuable reference to rebuild the forecast method of short-time severe rain- fall in the Pearl River Delta region.
出处
《气象》
CSCD
北大核心
2016年第2期144-155,共12页
Meteorological Monthly
基金
公益性行业(气象)科研专项(GYHY201506006)
华南区域气象中心气象科技攻关项目(GRMC2014M08)
广东省科技计划项目(20140218)
中国气象局强对流创新专家团队项目共同资助
