大气环境变化中大气颗粒物PM1的重要作用——关中平原MODIS气溶胶产品的气候分析

摘要

利用MODIS 3km气溶胶产品中的气溶胶光学厚度(AOD)和细粒子比例(FMF),本文对关中平原气溶胶近15a的时空变化进行了气候分析,揭示了大气环境变化中大气颗粒物PM1的重要作用.结果表明,关中平原为AOD高值区和FMF低值区.其中,最大值AOD出现在西安及周边地区高达1.06,而FMF主要集中在0.3以下较低水平.伴随关中平原近几年大气气溶胶水平的降低,PM1比重却逐年上升.关中平原AOD年际变化在2001～2011年间为显著上升趋势,2011～2015年间则呈下降趋势;而2001～2015年之间FMF的年际变化呈现持续上升趋势,反映了逐年加重的人为气溶胶对大气环境的影响.近15a关中地区AOD与FMF区域变化的相互关系表明,大气气溶胶低水-(AOD＜0.5)时,伴随FMF上升,AOD显著减小;气溶胶较高水平(AOD＞0.5)时,AOD随FMF上升而增大这表明大气颗粒物PM1对区域清洁和污染大气环境变化均具有显著作用.%The temporal and spatial changes of aerosols over Guanzhong Plain in 15 years were climatologically analyzed in this paper,by using MODIS 3kin aerosol products including AOD (aerosol optical depth) and FMF (fine mode fraction).The results showed that Guanzhong Plain was an area with high AOD and low FMF.The highest value of AOD existed in Xi'an and the surrounding areas up to 1.06 while FMF was under 0.3 there.With the decreases in atmospheric aerosol levels over Guanzhong Plain in recent years,the proportion of the PM1 increased year by year.During 2001～2011,AOD values increased significantly and then became decreasing in most areas of Guanzhong Plain over recent 5 years.Meanwhile,FMF values showed a sustaining upward trend from 2001 to 2015,reflecting the influence of increasing anthropogenic aerosols on atmospheric environment.The relationship between 15-year averages of AOD and FMF over Guanzhong Plain presented that when atmospheric aerosol level was low (AOD＜0.5),AOD decreased with the increasing FMF,and when atmospheric aerosol level was high (AOD＞0.5),AOD increased with the increasing FMF,indicating that atmospheric particles PM1 contributed greatly to atmospheric environment changes both in clean and polluted regions.