雅安区域性暖区暴雨特征及其概念模型的建立

Characteristics of Rainstorm in Ya’an Regional Warm Zone and Its Conceptual Model Establishment

利用1990—2017年MICAPS资料、自动站资料及NCEP再分析资料,对雅安区域性暖区暴雨的时空分布特征进行分析,并从区域性暖区暴雨发生前(08时或20时)的高低空环流配置和物理量判别指标两个方面进行统计分析,建立雅安区域性暖区暴雨潜势预报概念模型。结果表明:(1)暖区暴雨在雅安中部出现最多,从中部向南向北递减。暖区暴雨的年际变化呈波状态势,主要出现在7、8月份,小时雨强大于20mm的高发时段为22时—次日02时。(2)通过高低空环流配置,建立两类概念模型:副高偏西型的低层东南风气流型和副高偏东型的低层气旋式扰动型。(3)副高偏西型的低层东南风气流型对低层的系统性动力抬升条件、暴雨发生前本地的水汽条件和热力不稳定条件要求较低,但对低层的水汽输送条件要求较高。副高偏东型的低层气旋式扰动型,则需注意在低层水汽通道未打开的的情况下,仍可发生暴雨。

Based on MICAPS data,automatic station data and NCEP reanalysis data from 1990 to 2017,the spatial and temporal distribution characteristics of heavy rain in Ya'an regional warm area are analyzed.The conceptual model of rainstorm potential prediction in Ya'an regional warm area is established by statistical analysis of circulation configuration and physical quantity discrimination index at high and low altitudes before rainstorm occurred(8 am or 8 pm).The results show that:(1)The rainstorm in the warm area occurs most in the central part of Ya'an,and declines southward to northward from the center.The interannual variations of rainstorms in warm regions fluctuate mainly in July and August.The high incidence period of hourly rainstorms stronger than 20 mm is 10 pm-2 am.(2)Two kinds of conceptual models are established through the configuration of upper and lower circulation:the low-level southeast wind flow pattern with the subtropical high west and the low-level cyclone disturbance pattern with the subtropical high east.(3)The low-level southeast wind pattern with the subtropical high west requires lower conditions of systematic dynamic uplift,local water vapor and thermal instability before rainstorm,but higher conditions of water vapor transport in the low-level.For the low-level cyclonic disturbance type with the subtropical high east,it is necessary to pay attention to the possibility of heavy rain even if the low-level water vapor channel is not opened.