The Research On Aerosol Radiative Forcing In Mid-eastern China Based On Modis And Ceres Datelite Data

China is high aerosol loading region.Aerosol is an important radiative forcing factor.It influences radiation balance by direct and indirect ways.Thus,the accurate calculation of aerosol radiation forcing is one of the effective methods to evaluate the aerosol climate effect.However,the estimates of aerosol radiative forcing are still uncertain.In this paper,we use satellite observations data to estimate the radiation forcing which can be compared with the numerical simulation results and play a role in the verification.According to percentile rank,we divide aerosol into polluted and clean scenes,then quantify aerosols radiative forcing starting from the definition of radiative forcing,and analyze the temporal and spatial changes of radiative forcing in Mid-Eastern China,compare the relative contribution of direct and indirect effects.The main results are as follows:(1)Aerosol caused negative sw radiation forcing at TOA in Mid-Eastern China,the largest radiation forcing is in spring,the smallest one is in winter.?Aerosol large area coincide with sw direct radiation forcing large area,mainly located in Sichuan,South China,North China,Huanghuai and other places.Average annual sw direct radiation forcing is about-4.4W/m2.The sw direct radiation forcing is about-5.0W/m2(-6.28?-3.62W/m2)and-4.6W/m2(-5.96?-2.95 W/m2)in spring and summer,respectively.The direct radiation forcing is about-3.8W/m2 in winter.? Average annual sw indirect radiation forcing is about-14.5W/m2.The Maximum value of-21.9W/m2(-27.55?-16.00W/m2)is in spring,and the large radiation forcing area is located in the south of China.The second one is-15.9 w/m2(-19.97?-7.84W/m2)in summer,Minimum value of-8.9 W/m2(-11.80?-6.10W/m2)is in winter.?Average annual sw total radiation forcing is about-17.8W/m2.The Maximum value of-24.8W/m2 is in spring,The second one is-19.30W/m2 in summer,Minimum value of-13.1 W/m2 is in winter.(2)Aerosol caused positive 1w radiation forcing at TOA in Mid-Eastern China,the largest radiation forcing is in summer,the smallest one is in winter.? Average annual 1w direct radiation forcing is about 3.0W/m2,the Spring and summer radiation forcing is larger,The main large area is located in the central region of China.The lw direct radiation forcing is about 4.5W/m2(3.54?6.08W/m2)and 4.6W/m2(2.66?5.48W/m2)in spring and summer,respectively.It is about 1.4 W/m2(0.95?1.73W/m2)and 1.5W/m2(1.25?2.50W/m2)in spring and summer,respectively.? Average annual 1w indirect radiation forcing is about 5.5W/m2,The Maximum value of 7.4W/m2(4.97?9.98W/m2)is in summer,The second one is 6.5 w/m2(5.05?8.71W/m2)in spring,Minimum value of 3.6 W/m2(2.29?4.35W/m2)is in winter.? Average annual lw total radiation forcing is about 9.0W/m2.Season average total radiation forcing is about 12.0W/m2 and 12.7W/m2 in spring and summer,respectively.It is about 6.6W/m2 and 4.9W/m2 in autumn and winter.(3)Aerosol caused negative net radiation forcing at TOA in Mid-Eastern China.? Average annual net direct radiation forcing is about-3.5W/m2,The Maximum value of-4.6W/m2(-6.21?-3.44W/m2)is in autumn,the Minimum value of-2.5 W/m2(-3.63?-1.82W/m2)is in summer.? Average annual net indirect radiation forcing is about-6.7W/m2,the maximum value of-12.1 W/m2(-15.11?-8.78 W/m2)is in spring,the minimum value of-4.0 w/m2(-5.86?-2.98 w/m2)is in winter.? Average annual net total radiation forcing is about-8.7 W/m2,the maximum value of-12.8 W/m2 is in spring.Seasonal average net total radiative forcing about-6.6 W/m2 and-7.2 W/m2 in summer and winter,which are relatively small.(4)? Aerosol indirect effect has a great effect on shortwave radiation,and the indirect effect in spring is the largest,followed by summer.In addition,the relative contribution of indirect effects where AOD is high would be reduced,but the indirect effect is greater than the direct effect.? As for longwave radiation,there is little difference in the relative contribution of seasonal changes,but there are differences in the spatial distribution.? The relative contribution of indirect effects of net radiation in spring and summer is greater than that in autumn and winter.The influence of aerosol on the net radiation in most parts of the eastern part of China is dominated by indirect effect,and the local area is dominated by direct effect.