能量参数在中川机场雷暴预测中的应用

Application of Some Simulated Energy Index to Thunderstorm Forecast at Zhongchuan Airport

我国目前的大气探空网,其时空观测密度尚不足以捕捉强对流天气信号。采用中尺度数值模式MM5对发生在兰州中川机场的5次雷暴天气进行模拟,利用模拟结果并结合地面观测资料,计算、分析了雷暴发生、发展过程中一些对流活动指数的变化,结果表明,对流有效位势能量(CAPE)和对流抑制能量(CIN)对中川机场雷暴预测有较好的指示意义,当CAPE>20 J.kg-1时就可能出现雷暴,>100 J.kg-1时雷暴较强;经过地面资料修正的CAPE能够更准确地预测雷暴发生时间,描述雷暴发展过程中的能量积累和释放过程;同时指出,使用数值模式预测雷暴时,积分时间不易过长。

The sounding observation net in China is not sufficient for mesoscale convection system activity study. Nemerical simulation results could provide the souding data at some extent for the places where there are no souding observations and the times when it not the souding time. Here, nonhydrostatic mecoscale MM5 model products were used to model the thunderstorms activities at Lanzhou Zhongchuan airport during 10-11 and 24-25 June 2005. The simulated results show that the Convective Available Potential Energy （CAPE） and Convective Inhibition （CIN） is more indicative than other indexes. It will be possible for dry thunderstorm occurring when CAPE is larger than 20 J · kg^-1. Precipitation take place in thunderstorm when CAPE is larger than 100 J · kg^-1. Due to the bias of air temperature and humidity at lower atmosphere, the calculation of CAPE and CIN is amended. The simulated air temperature and humidity in the lower atmosphere are replaced by the observations at Zhongchuan airport and the simulated souding data is used. It is found that CAPE after amending could predict the timing of thunderstorm happening and could desclzibe the energy accumulation and releasing process than the simulation results. It is pointed out that the simulation result is not so good as within it when the integrat time longer than 36 hours for thunderstorm prediction.