南疆短时强降水概念模型及环境参数分析

Analysis of Conceptual Models and Ambient Parameter of Short-Time Severe Rainfall in South Xinjiang

利用南疆2010-2016年自动气象站及区域自动气象站逐小时降水量资料,NCEP/NCAR 1°×1°再分析资料以及探空资料,分析不同强度的短时强降水的时空分布,得出南疆短时强降水事件的天气型有明显的季节性特点和区域性特征。总结了典型短时强降水过程的环境背景场特征,建立了短时强降水的三种概念模型:中亚低槽(涡)型、西伯利亚低槽(涡)型和西风短波型。通过7个探空站的温湿廓线形态、地面露点温度、T_(850)-T_(500)、T_(700)-T_(500)、对流有效位能(CAPE)、对流抑制能量(CIN)、抬升凝结高度、0～6 km垂直风切变等分析了南疆短时强降水的环境背景:短时强降水Ⅰ型(整层湿)、短时强降水Ⅱ型(上湿下干)和短时强降水Ⅲ型(上干下湿)发生前大气水汽含量充沛、存在一定的CAPE和较明显的垂直风切变以及0℃层高度偏低、暖云层厚度偏厚等特征,而合适的CIN,有利于对流不稳定能量的积聚和爆发,促进短时强降水的发生;短时强降水Ⅳ型(干绝热型)存在大气层结较干和较大的T_(850)-T_(500)、T_(700)-T_(500);Ⅰ型和Ⅱ型是南疆短时强降水的主要类型,常出现在南疆中部、西部地区的盛夏和夏末,多为西伯利亚低值系统(低涡、低槽)型和中亚低值系统(低涡、低槽)型影响。

The spatio temporal distribution of short time severe rainfall with different intensities was analyzed by using the hourly precipitation data of automatic weather station and regional automatic weather station, the NCEP/NCAR 1°×1° reanalysis data and the sounding data during 2010-2016. It is concluded that the weather pattern of the short time severe rainfall events in South Xinjiang has seasonal and regional characteristics obviously. Based on the characteristics of the environmental background of typical short time severe rainfall, three conceptual models of short time severe rainfall were established： Central Asia low trough （vortex） type, Siberian low trough （vortex） type and westerly short wave type. The ambient background of the short time severe rainfall events in South Xinjiang was analyzed by the temperature and humidity profiles of seven sounding stations, ground dew point temperature,T850-T500,T700-T500,convective available potential energy （CAPE）, convective inhibition （CIN）, uplift condensation height, 0-6 km vertical wind shear etc. For short time severe rainfall Type Ⅰ （whole layer wet）, short time severe rainfall Type Ⅱ （under the wet dry） and short time severe rainfall Type Ⅲ （upper dry wet）, before the occurrence, there are abundant atmospheric water vapor, a certain CAPE obvious vertical wind shear as well as low 0℃ layer height, thick warmth cloud thickness and other characteristics. The appropriate CIN is favorable for the accumulation and explosion of the convective unstable energy, promoting the occurrence of short time severe rainfall. For the short time severe rainfall Type Ⅳ （dry adiabatic）, the atmospheric stratification is relatively dry, and the T850-T500and T700-T500are relatively high. The Type Ⅰ （low vertex） and Type Ⅱ （low trough） are the main types of short time severe rainfall events in South Xinjiang which are often seen in the central and western parts of South Xinjiang, from mid summer to the end of summer, due to the influence of the Siberian low value system （low vortex, low trough） type and low value system in Central Asia （low vortex and low trough） type in the middle and southern regions of the southern part of China.