Characteristics of aerosol extinction and low visibility in haze weather in winter of Nanjing
HE Jia-qi, YU Xing-na, ZHU Bin, YUAN Liang, MA Jia, SHEN Li, ZHU Jun
Key Laboratory of Meteorological Disaster, Ministry of Education, Joint International Research Laboratory of Climate and Environment Change, Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China
The variation characteristics of aerosol scattering and absorption coefficients, their contributions to atmospheric extinction and the relationship between visibility, PM2.5 mass concentration and relative humidity were presented based on the aerosol absorption and scattering coefficients, PM2.5 mass concentration, visibility and meteorological data in January 2015 in Nanjing. The results indicated that aerosol scattering and absorption coefficients were (423.4±265.3) Mm-1 and (24.5±14.3)Mm-1, and their contribution to the atmospheric extinction were 89.2% and 5.2% respectively. The atmospheric extinction was mainly contributed to the aerosol scattering during observation period. The relationship between aerosol scattering coefficient and PM2.5 mass concentration showed a good agreement (R2=0.91). The visibility decreased exponentially with PM2.5 mass concentration, and showed a negative correlation with relative humidity. The mean visibility during the observation period was 4.3km, and low visibility episodes ( < 2km) frequently happened. Light extinction coefficient and PM2.5 mass concentration during haze episodes were evidently higher than those of non-haze periods with the highest values during haze episodes reached 1471.2Mm-1 and 358μg/m3 respectively. The visibility degradation was contributed to the influences of particles and relative humidity.
Wang Kaicun, Dickinson R E, Shunlin L. Clear Sky Visibility Has Decreased over Land Globally from 1973 to 2007 [J]. Science, 2009,323(5920):1468-1470.
[2]
Wu D, Tie X, Li C, et al. An extremely low visibility event over the Guangzhou region: A case study [J]. Atmospheric Environment, 2005,39(35):6568-6577.
Deng X, Tie X, Wu D, et al. Long-term trend of visibility and its characterizations in the Pearl River Delta (PRD) region, China [J]. Atmospheric Environment, 2008,42(7):1424-1435.
[6]
Campbell F W, Robson J G. Application of fourier analysis to the visibility of gratings [J]. Journal of Physiology, 1968,197(3):551- 566.
[7]
Ying I T. Atmospheric visibility trends in an urban area in Taiwan 1961~2003 [J]. Atmospheric Environment, 2005,39(30):5555-5567.
J, Stutz, U, Platt. Numerical analysis and estimation of the statistical error of differential optical absorption spectroscopy measurements with least-squares methods [J]. Applied Optics, 1996,35(30):6041-6053.
[16]
Hansen A D A. The aethalometer [EB/OL]. http://sirta.ipsl. polytechnique.fr/parisfog/images/stories/parisfog2010/Doc_Instruments/Aethalometer_book.pdf [2011-07-01].
Bergstrom R W, Russell P B, Hignett P. Wavelength Dependence of the Absorption of Black Carbon Particles: Predictions and Results from the TARFOX Experiment and Implications for the Aerosol Single Scattering Albedo [J]. Journal of the Atmospheric Sciences, 2002,59(3):567-577.
[19]
Penndorf R. Tables of the Refractive Index for Standard Air and the Rayleigh Scattering Coefficient for the Spectral Region between 0.2 and 20.0μ and Their Application to Atmospheric Optics [J]. Josa, 1957,47(2):176-182.
[20]
Sloane C S, Wolf G T. Prediction of ambient light scattering using a physical model responsive to relative humidity validation with measurements from Detroit [J]. Atmospheric Environment, 1985,19(4):669-680.
Junge C. The size distribution and aging of natural aerosols as determined from electrical and optical data on the atmosphere [J]. Journal of Meteorology, 1955,12(1):13-25.
[30]
J. Chen, C. S. Zhao, N. Ma, et al. A parameterization of low visibilities for hazy days in the North China Plain [J]. Atmospheric Chemistry & physics & Discussions, 2012,11(11): 4935-4950.
Draxler R R. Description of the HYSPLIT _4modeling system[R]. NOAA Technical Memorandum, 1997.
[36]
中央气象局.地面气象观测规范 [M]. 北京:气象出版社, 2003: 21-27.
[37]
中国气象局.霾的观测与预报等级 [M]. 北京:气象出版社, QX/T113-2010.
[38]
Liu X, Zhang Y, Cheng Y, et al. Aerosol hygroscopicity and its impact on atmospheric visibility and radiative forcing in Guangzhou during the 2006PRIDE-PRD campaign [J]. Atmospheric Environment, 2012,60(6):59-67.
