清远市森林火险气象指数变化特征分析

Analysis on the Change Characteristics of Forest Fire Weather Index of Qingyuan City

利用清远市气象站1976—2015年逐日气象观测资料,通过布龙-戴维斯方案及修正后的布龙-戴维斯方案计算出森林火险气象指数,采用线性倾向估计法、Mann-Kendall突变检验、小波分析等方法,分析清远市森林火险变化特征。结果表明,近40年来清远市森林火险气象指数增长趋势明显,火险指数年内变化具有季节性特征,从夏季开始逐渐增加,9月—次年2月指数比较高,10月份达到峰值,春季开始指数逐渐下降,5月降至最低值;Mann-Kendall突变检验分析表明,从20世纪80年代初火险指数呈明显上升趋势,上升的突变点是1994年;小波分析表明,火险指数存在16~32、11~23年尺度的准2次振荡,27年左右的周期振荡最强,为指数变化的第1主周期,18和5年时间尺度分别为指数变化的第2、第3主周期,3个周期的波动控制着指数在整个时间域内的变化特征。

Using daily meteorological observation data from Qingyuan City Meteorological Station from 1976 to 2015,the forest fire weather index was calculated by the Bron-Davies scheme and the modified Bron-Davies scheme,the linear tendency estimation method,Mann-Kendall mutation,wavelet analysis and other methods were used to analyze the change characteristics of forest fire in Qingyuan City. In the past 40 years,the growth trend of forest fire weather index in Qingyuan City had been obvious. The change of forest fire weather index had seasonal characteristics,it began to rise in the summer,September to February was higher,the peak appeared in October. It began to fall from spring,the lowest value appeared in May. Mann-Kendall showed that the forest fire weather index had been on the rise since the early 1980 s,the rising point of mutation was 1994.Wavelet analysis showed that the forest fire weather index appeared Quasi two concussion of 16-32 years and 11-23 years scale,the period of27 years was the strongest,which was the first main period of index changes,the 18 and 5 year scales were the second and third main period of index changes. The fluctuations in the three cycles control the change characteristics of the index in the whole time domain.