000030009 001__ 30009
000030009 041__ $$aEnglish
000030009 100__ $$aZhuang, B. L.
000030009 245__ $$aOptical Properties and Radiative Forcing of Urban Aerosols in Nanjing, China
000030009 260__ $$c2014
000030009 269__ $$c2//
000030009 300__ $$a43-52
000030009 500__ $$aOpen access article
000030009 520__ $$aContinuous measurements of atmospheric aerosols were made in Nanjing, a megacity in China, from 18 January to 18 April, 2011 (Phase 1) and from 22 April 2011 to 21 April 2012 (Phase 2). Aerosol characteristics, optical properties, and direct radiative forcing (DRF) were studied through interpretations of these measurements. We found that during Phase 1, mean PM2.5, black carbon (BC), and aerosol scattering coefficient (Bsp) in Nanjing were 76.1 ± 59.3 μg m−3, 4.1 ± 2.2 μg m−3, and 170.9 ± 105.8 M m−1, respectively. High pollution episodes occurred during Spring and Lantern Festivals when hourly PM2.5 concentrations reached 440 μg m−3, possibly due to significant discharge of fireworks. Temporal variations of PM2.5, BC, and Bsp were similar to each other. It is estimated that inorganic scattering aerosols account for about 49 ± 8.6% of total aerosols while BC only accounted for 6.6 ± 2.9%, and nitrate was larger than sulfate. In Phase 2, optical properties of aerosols show great seasonality. High relative humidity (RH) in summer (June, July, August) likely attributed to large optical depth (AOD) and small Angstrom exponent (AE) of aerosols. Due to dust storms, AE of total aerosols was the smallest in spring (March, April, May). Annual mean 550-nm AOD and 675/440-nm AE were 0.6 ± 0.3 and 1.25 ± 0.29 for total aerosols, 0.04 ± 0.02 and 1.44 ± 0.50 for absorbing aerosols, 0.48 ± 0.29 and 1.64 ± 0.29 for fine aerosols, respectively. Annual single scattering albedo of aerosols ranged from 0.90 to 0.92. Real time wavelength-dependent surface albedo from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to assess aerosol DRFs. Both total and absorbing aerosol DRFs had significant seasonal variations in Nanjing and they were the strongest in summer. Annual mean clear sky TOA DRF (including daytime and nighttime) of total and absorbing aerosols was about −6.9 and +4.5 W m−2, respectively. Aerosol DRFs were found to be sensitive to surface albedo. Over brighter surfaces, solar radiation was more absorbed by absorbing aerosols and less scattered by scattering aerosols.
000030009 653__ $$aAerosols
000030009 653__ $$aOptical Depth
000030009 653__ $$aSingle Scattering Albedo
000030009 653__ $$aAngstrom Exponent
000030009 653__ $$aRadiative Forcing
000030009 653__ $$aNanjing
000030009 700__ $$aWang, T. J.
000030009 700__ $$aLi, S.
000030009 700__ $$aLiu, J.
000030009 700__ $$aTalbot, R.
000030009 700__ $$aMao, H. T.
000030009 700__ $$aYang, X. Q.
000030009 700__ $$aFu, C. B.
000030009 700__ $$aYin, C. Q.
000030009 700__ $$aZhu, J. L.
000030009 700__ $$aChe, H. Z.
000030009 700__ $$aZhang, X. Y.
000030009 773__ $$pAtmospheric Environment
000030009 773__ $$v83 (0)
000030009 773__ $$ahttp://dx.doi.org/10.1016/j.atmosenv.2013.10.052
000030009 8564_ $$uhttp://www.sciencedirect.com/science/article/pii/S1352231013008054$$yExternal link (Open access)
000030009 980__ $$aARTICLE