1、Some evidence for aerosol regional climate effects in China Yunfeng LuoDepartment of Earth Sciences, National Nature Sciences Foundation of China, Beijing 100085 Email: ,Some evidences for China regional climate change Distribution and Variation Patterns of yearly mean aerosol optical depth over Chi
2、na in recent 30 years.Sensitive test for regional surface temperature responseUncertaintiesConclusion,Yearly mean temperature change in China during the period from 1950s to 1980s,Shadowed lines is the cooling areas,1980s-1950s,Jan.,July,Tibet,Tibet,South Xinjiang basin,North east,North,East,South,S
3、outh west,Middle,Northwest Part1,Northwest Part2,Sichuan Basin,the largest developing country with the most population in the world, has been using coal as the major energy supply for many years. This makes China one of the areas polluted heavily by sulfate aerosols. In addition, the mineral aerosol
4、, which was derived from northwest China, especially in spring, can transfer along with the upper wind to far away downstream and impact the environment and climate of east China and adjacent areas,The location of 46 solar radiation stations in China,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,2
5、8,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,The distribution of yearly mean (1961-1990) aerosol optical depth over China,The distribution of aerosol optical depth for 1960s over China,1980S-1960S(July),1980S-1960S,The linear trend *10（yr-1）of AOD over China mainland,The highest value (0.
6、011 yr-1) happened in the middle reaches of the Yangzi River:,Inter-annual variation of mean aerosol optical depth in China,Of the total 46 stations, the yearly averaged AOD variation curve can be briefly divided into two periods. One period is from 1961 to 1975, when AOD is smaller than the 30 year
7、 mean value; the other period is from 1976 to 1990, when AOD is higher than the mean value. Except for the peak in 1982 and 1983, which may be attributed to the eruptions of EI Chichon, the curve shows a significant increasing trend from 1961 to1990. The monthly averaged AODs of the total 46 station
8、s also obviously increased.,Domain of China Regional Climate Model,Horizontal grid 100km,AOD patterns for four months in 1980s,Jan.,April,July,Oct.,Monthly mean aerosol radiative forcing for clear-sky ( Wm-2 ),Jan.,April,July,Oct.,Monthly mean aerosol radiative forcing ( Wm-2 ),Jan.,April,July,Oct.,
9、Jan,July,Monthly mean cloud cover (0-1),Jan.,Monthly mean surface air temperature response,Integrate one year,April,Monthly mean surface air temperature response,July,Monthly mean surface air temperature response,October,Monthly mean surface air temperature response,Four months(Jan.,Apr.,July,Oct.)
10、averaged surface air temperature response,yearly mean,Jan.(Integrate),The synthesized map of the monthly mean surface wind field and the aerosol radiative forcing distribution as well as the surface air temperature response,April,July,Oct.,The value and the distribution of surface air temperature re
11、sponse are different from that of aerosol optical depth and radiative forcing pattern. The cooling regions are related to the areas in the downwind areas of higher radiative forcing regions in 500hpa-wind field and in the convergent areas in surface wind field. But the lower-value cooling regions ar
12、e related to the divergent areas of the surface wind field.,Uncertainties,Table . Response of Multiyear Averaged AOD to 5% Increase of,and are both within 2%, the solution error will within 0.02, 0.01, and 0.006 for 0=1, 0.5, and 0.3, respectively.,Table 7. Multiyear Averaged AOD for Different Treat
13、ment of Monthly Mean Cosine Solar Zenith Anglea,a , AOD caculated by using siplified monthly mean cosine solar zenith angle as in this paper; m, AOD caculated by using real monthly mean cosine solar zenith angle m; mm, AOD caculated by using the daily mean cosine solar zenith angle of the midday in
14、a month.,Table. Multiyear Averaged AOD for Different Treatment of Monthly Mean Cosine Solar Zenith Anglea,Mean Value of AOD for 1980-1990 for Stations Calculated by Qiu and This Paper,The comparison of 0.75-m AOD from this paper and Mao et al.s results for period July 1980 to July 1981,On the other
15、hand, because most of the stations that we used are located in the big cities, it is thus biased that using these cities AOD value to describe the AOD distribution for the whole China mainland. We supposed that aerosol single scatter albedo is 1,i.e.,not consider the absorbing.,Prof. James Hansen an
16、d his colleagues just carry out climate simulations (GISS CLIMATE MODEL) days ago and have some interesting results.,the result suggest that human-made aerosols may tend to increase rainfall in South China and decrease rainfall in North China during the rainy season, in the sense of the observed tre
17、nd in recent decades (“flood south, drought north”),but with the aerosol single scatter albedo, SSA = 0.85 in China. This aerosols also cause summer cooling in Eastern China, of a magnitude comparable to that observed in the past 50 years.In a companion experiment With SSA = 1, does not yield the st
18、rong changes in rainfall patterns and the surface cooling is reduced.,In recent 30 years, the direct solar radiation and sunshine duration as well as visibility decreased obviously.The decrease of direct solar radiation and sunshine duration were caused not the enhancement of cloud cover, but the de
19、crease of surface visibility and total atmospheric aerosol amounts. From 1961 to 1990 the mean AOD shows an obvious increasing trend over China.,Conclusion,AOD increased most significantly in those high economics developing areas (eastern part of the Sichuan Basin, northern part of Guizhou Province,
20、 middle and lower reaches of Yangzi River). Generally the yearly mean AOD has pattern related to the geographical features with the maximums over basins.Since 1980s,the eastern part of china have being the other high-value AOD areas,this main attribute to the human activities,When considering the ae
21、rosol radiative forcing effect in regional climate model,the surface temperature response is partly similar to the observational facts. There are still large uncertainties in estimation of aerosol properties in our work,so it is important to strengthen the field observation in China, and we also nee
22、d to pay more attention to develop the retrieve method for AOD,imagery index and so on in the future.,The endThank you very much for listening,Principles and Methods:Monthly mean aerosol optical depth is calculated as following:(1) Suppose G0=1(2) Let n=1(3) = log(RS0tmG(n-1) - log( )(4) G(n) =( 1+
23、b + c)f1 , （*=2.5)(5) n=n+1, repeat step3 and step4(6) when Abs (1- ) ，end iteration. =0.001 in this paper Among them, S is the direct solar radiation and S0 is the solar constant; R refer to the ratio between the solar radiation in the range of 0.3m to 4m and S0 , and tm stands for the average mole
24、cular transmittance in the range.,G0(n)： G0(n) =( 1+ b + c)f2 b =(0.38-0.910+0.53602)( *-2)-(0.38-0.640+0.3402)( *-2)2 c = (0.87-2.060+1.1902)( *-2)+(1.39-30+1.702)( *-2)2 f2 =1+0.158( *-2)(1-0.889U)/(1+0.3U+903 U1/2) Unlike Qius method, the surface pressure、surface water pressure and ozone concentr
25、ation we used here are all the monthly mean value. When we retrieved the 0.75m aerosol optical depth from the solar direction radiation, the effective moisture amounts is needed, which was get through the experimental equation with surface moisture pressure. Monthly ozone amount get from TOMS versio
26、n-7 data. In this paper: ：monthly mean direct solar radiation ：monthly mean solar ordinate,n :the amount of days in a month ：monthly mean solar zenith angle. Its value is half of the maximum solar zenith angle for the middle day of a month. D is counted from first Jan.,forcing( seasonal ave.),Response (seasonal ave.),
