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.
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