柳州市高森林火险气象条件及等级预报研究

Meteorological Conditions of Forest Fire Danger and Analysis on Weather Ratings Forecast in Liuzhou

利用柳州市7个国家气象站1987—2017年逐日气象资料和同期的NECP/NCAR逐月再分析资料,以及柳州市2010—2018年的林火资料,分析了柳州市高森林火险的大气环流和气象条件特征。结果表明:春季高森林火险年东亚大槽较常年同期偏弱,我国中西部地区位势高度偏高,冬季高森林火险年乌拉尔山以西部地区位势高度偏高,低纬地区为平直的西风气流控制,气流在长江流域汇合,广西维持高温少雨是森林火险高的环流背景;当降水在0.2 mm以下(或无降水)、日最大风速在3.0~4.0 m/s、日最高气温在24℃~28℃、日最小相对湿度在20%~40%时,柳州极易发生火灾;经过柳州市本地化后的行标较国标更能客观地反映柳州森林火险气象条件的危险程度,可业务应用。

Based on the daily meteorological data at 7 national weather station in Liuzhou during 1987-2017,the homochronous monthly reanalysis data from NECP/NCAR and forest fire data from the headquarter of Liuzhou forest fire prevention during 2010-2018,the variation characteristics of forest fire was investigated by defining the meteorological environment index of the forest fire danger.And on this basis the atmospheric circulation features of the typical years with high forest fire danger were analyzed further in spring and winter,combined with the typical case,the correlativity of meteorological elements and forest fire insurance was studied.The results displayed that:the east asia deep trough of the 500 hPa geopotential height field in typical years of high forest fire danger in spring was negative,and that was positive in central and western of china.In winter,circulation pattern of the 500 hPa geopotential height anomaly field in typical years of high forest fire danger was positive in the western region of Ural Mountains,the low-latitude area was controlled by the horizontal westerly airflow,Thus the cold air was accumulated in the middle and high latitudes,which resulted in the location of the main frontal zone of weather system to northward;There was very prone to fire when the precipitation was below 0.2 mm,no precipitation,the daily maximum wind speed was between 3 and 4 m/s,the daily maximum temperature was between 24℃ and 28℃ and the daily minimum relative humidity was between 20% and 40%;compared with the national standard,the localized industry standard can objectively reflect the degree of danger of Liuzhou’s forest fire danger meteorological conditions,and can be applied for business.