CI指数在大兴安岭地区春季防火服务中的应用

Application of CI Index in Spring Forest Fire Warning Service in Daxinganling Mountain Area

用综合气象干旱指数(CI),结合1980—1999年林火资料,选取上年夏秋季、3月及前20天累计干旱指数作为CI林火因子,分别代表长期、中期和近期的气象干旱情况,并依据CI林火因子计算出CI林火指数(Hc)进行林火预警服务。经过研究得出如下结论:①各月相比,6月的林火因子最小,5月除上年夏秋季累计干旱指数小于4月外,其他因子均大于4月和6月累计干旱指数,说明5月最易着火,而6月出现火灾时比4月需要更加干旱的气象条件。②4月和6月有89%林火个例的Hc<1,5月有84%的林火个例达到这个标准;当Hc≥2时,有76%的年份在10天内发生林火,平均每年发生4次,而Hc<2时只有45%的年份发生林火,平均每年发生2.3次。说明Hc越大,发生林火的可能性越大。在春季森林火险预警服务中,可定义Hc≥2为高火险,1≤Hc<2为中火险,Hc<1为低火险。

Selecting the∑CI（CI：Comprehensive meteorological drought Index）of the summer-autumn, March,and the previous 20days of the previous year as forest fire CI to represent the long-term,mediumterm,and current meteorological drought conditions,by means of the comprehensive meteorological drought index and forest fire information from 1980to 1999,forest fire warning service is provided with Hc（forest fire CI）.The analysis concludes：（1）in the whole year,the minimum forest fire factor was in June;∑CI in May was greater than those in April and June except the previous summer-autumn（∑CI was lower than that in April）.（2）89% of the samples occurred in April and June when Hc1,and in May there were 84% of the samples with Hc1.When Hc≥2,there occurred a forest fire in ten days in 76% of years,on average 4times per year;when Hc2,there occurred a fire only 45% of years,on average 2.3times per year.Therefore,it can be seen that when Hc≥2,it has high fire risk,when 1≤Hc2,it has moderate fire risk and when Hc1,it has low fire risk in spring forest fire warning service.