Analysis on the Influencing Factors of the Change of Haze Day in Guilin

Based on the surface meteorological data and PM_2.5 data observed at Guilin Meteorological Observatory from 1981 to 2015,this paper analyzes the influencing factors of the change of Haze Day in Guilin.The results show that the number of haze days in Guilin has an obvious rising trend in the past 35 years,and its climate tendency rate is 24.6 d/10 a.In 1995,it experienced an obvious abrupt change,which is mainly due to the change of human activities and meteorological factors.The PM_2.5 concentration in each factor affects the monthly and daily distribution of Haze Days,of which January and July are PM_2.5 for high and low value months in Guilin,which is also the most haze occurrence,the least month.The trend of PM_2.5 concentration and haze frequency Day Change is similar,all are bimodal distribution.Among the meteorological factors,the decrease of precipitation ≥0.1mm,maximum wind speed ≥5m.s^-1 days and the decrease of average annual relative humidity are the important reasons for the increase of haze,and the inverse temperature also affects the daily and monthly distribution of haze,which can better reflect the level of PM_2.5 concentration during haze with inversion layer thickness and height.