| This paper analyzed the basal climatic characteristics of thunderstorm in Guangdong province, the impact of urbanization on the Pearl River Delta and the correlation of the Western Pacific Pool and thunderstorm in Guangdong province, which used the thunderstorm and temperature observation data of 26 weather stations from 1960 to 2013 in Guangdong province, as well as global sea surface temperature data, MEI index data,some lightning location data and satellite imagery data, combined with climate trend coefficient analysis, Mann-Kendall mutation test, wavelet analysis, and EOF analysis, in addition, a strong thunderstorm process in Zhanjiang East Island were analyzed too. The main results are as follows:(1)Guangdong province has a lot of thunderstorms, the annual average is 74.3 d/a, and began to decline after 1984, about 4.4 days per decade decrease. Seasonal variations is obvious, about 90.7 percent thunderstorms occurs in April to September, and the thunderstorms occurs in summer is the mainly parts. Annual changes of thunderstorm and temperature have the same trend, and the correlation coefficient is 0.8894. Thunderstorm in Guangdong province appears before mid- April, and can last a long time.(2) Thunderstorm in Guangdong province exist 2-3 years and 4-5years short-period oscillation characteristics, and has a 21-22 years long-term oscillation characteristics exist in the whole period.(3)There has more thunderstorms in Guangdong province before 1983, but began to decline after 1984, and the transition occurs in 1983-1984.(4)The spatial distribution characteristic of thunderstorm days in Guangdong province is the western regions more than eastern. Xinyi(97.4 d/a) and Xuwen(90.4 d/a) have the largest number of thunderstorm days, and Nanao(44.4 d/a) and Shantou(45.9 d/a) on their contrary.(5)There have three modes of spatial anomaly in Guangdong: the accordant anomaly,reverse anomaly between north and south, reverse anomaly between eastern and western,and the first one is the mainly one.(6)Heat island effect in Pearl River Delta increased thunderstorm days to a certain extents,but had little effect compared with the weather system. For different cities have them own characteristics, so can not comparison all cities with the same standard.(7)Thunderstorm in Guangdong province and the Western Pacific Warm Pool was a consistent inverse relationship, and the western areas has a larger crosscurrent strength than eastern.(8) The thunderstorm process under both influence of the high level trough and weak cold flow, and the current intensity and steepness of lightning flash are-54.463 66 k A and28.665 08 k A/μs, respectively. The location of lightning strike was identical with low vortex cloud cluster, accompanied with radar echo intensities exceeding 45 d BZ, the clockwise wind direction with height, as well as obvious abrupt change in precipitation,wind speed and direction, local pressure and visibility around flash location in lightning strikes process. The vertical distribution of horizontal wind speed fluctuated with jet area at height of 1.8 km, and the fluctuation of profiles increased after lightning strike. It appeared high value and stable area of vertical velocity at altitude of 2—5 km before lightning strike,which changed abruptly after strike with enhanced fluctuation and significant peak and valley values. The distribution of horizontal wind direction changed significantly before and after the lightning process, which appeared opposite characteristics in the low level.The vertical distribution of wind direction were relatively dispersed with larger virtual temperature of 28.71 ℃in the low level of atmosphere, and became jumping distribution in the low and middle part. It was the transition stage from unstable to stable atmosphere when lightning happened, and the interactions among weak cold air, intense precipitation and thunderstorm consumed large amounts of energy and water vapor, which resulted in stable atmosphere. |
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