摘要
It has been suggested that forest fires will become more frequent/intense with changing climate,which would increase aerosol/gas emissions into the atmosphere.A better under-standing of the relations between meteorological conditions,fires,and fire emissions will help estimate the climate response via forest fires.In this study,we use ERA5 meteor-ological products,including temperature,precipitation,and soil moisture,to explain the frequency of forest fires and the amount of radiant energy released per time unit by burning vegetation(fire radiative power,FRP).We explore the relation-ships between satellite-retrieved fire products and aerosol properties(aerosol optical depth,AOD),carbon monoxide(CO),formaldehyde(HCHO),and nitrogen dioxide(NO_(2))con-centrations over the PEEX domain,which covers different vegetation zones(e.g.croplands/grasslands,forest,arctic tun-dra)of Pan-Eurasia and China.We analyse the concentrations of black carbon and absorbing organic carbon using groundbased AErosol RObotic NETwork.The analysis covers the months of May to August from 2002 to 2022.We show posi-tive temperature trends in the Northern zone(>65°N)in June and August(1.56°C and 0.64°C,respectively);all statistically significant trends for precipitation and soil moisture are nega-tive.This can explain increased fire activity in Siberia over the recent years(2019-2022).Over the whole PEEX domain,FC and FRP trends remain insignificant or negative;a decrease in AOD may address those negative trends.We show that intrasummer variations exist for cropland/grassland fires,which occur most often in May and August,while Siberian forest fires occur more often in July and August.We show that CO concentration has been gradually decreasing in the last two decades in May and June.CO trends are negative in May,June,and over summer for all regions,in July in Europe,China,the Southern zone(<55°N),and the PEEX domain.HCHO trends are not significant in all regions.NO_(2)trends are positive in May and negative in June in all zones.We calculated total column enhancement ratios for satellite obser-vations influenced by wildfires.A common feature has been recognized with measurements and ratios utilized in SILAM(System for Integrated Modelling of Atmospheric Composition):AOD(or PM):CO and AOD(or PM):HCHO ratios for grass are clearly lower than for shrubs,opposite for AOD:NO_(2).We showed that emission ratios are increasing towards South and are 2-3 times higher for high(>0.5)AOD.Using a 21-year satellite record of the AOD and CO,an 18-year record of NO_(2),and a 16-year record of HCHO,we created background products of those variables over the PEEX domain.In the regions with low anthropogenic activity and conditions where long-range transport is not happening,anomalies in AOD,CO,and HCHO over biomass-burning areas may be assigned directly to the wildfire emissions.
