TY - GEN
T1 - Impacts of aerosol compositions on visibility impairment in Xi'an, China
AU - Cao, Jun Ji
PY - 2012
Y1 - 2012
N2 - Daily dry particle light scattering coefficients, PM2.5, NO2 were collected in Xi'an from February 15 to December 31, 2009 to investigate the causes of visibility degradation and its temporal variability. Average VR was 6.4±4.5 Km, with the largest seasonal variations found in spring (1.5 to 28.5 Km), followed by summer (1.2 to 18.9 Km). The lowest VR was found in winter (0.8 to 10.7 Km). Diurnal particle light scattering coefficients (bsp,dry) showed early morning and late evening peaks with a low in the afternoon hours. This diurnal cycle was likely due to variations of emission sources and meteorological conditions. Elevated PM2.5 mass was associated with VR <10 Km, and a PM2.5 threshold value of 88 μg m-3 (i.e., low visibility occurs when PM2.5 > 88μg m-3).Based on the revised IMPROVE equation, (NH4)2SO4 was the largest contributor, accounting for 39.8% of light extinction coefficient, followed by OM (23.8%), NH4NO3 (23.1%), and EC (9.1%), with minor contribution from soil dust (3.4%) and NO2 (0.8%). Chemical extinction was ∼15% lower than optical extinction, but they were highly correlated. Elevated concentrations of secondary aerosol species (i.e.SO42- and NO3-) were the main causes of VR <5 Km.
AB - Daily dry particle light scattering coefficients, PM2.5, NO2 were collected in Xi'an from February 15 to December 31, 2009 to investigate the causes of visibility degradation and its temporal variability. Average VR was 6.4±4.5 Km, with the largest seasonal variations found in spring (1.5 to 28.5 Km), followed by summer (1.2 to 18.9 Km). The lowest VR was found in winter (0.8 to 10.7 Km). Diurnal particle light scattering coefficients (bsp,dry) showed early morning and late evening peaks with a low in the afternoon hours. This diurnal cycle was likely due to variations of emission sources and meteorological conditions. Elevated PM2.5 mass was associated with VR <10 Km, and a PM2.5 threshold value of 88 μg m-3 (i.e., low visibility occurs when PM2.5 > 88μg m-3).Based on the revised IMPROVE equation, (NH4)2SO4 was the largest contributor, accounting for 39.8% of light extinction coefficient, followed by OM (23.8%), NH4NO3 (23.1%), and EC (9.1%), with minor contribution from soil dust (3.4%) and NO2 (0.8%). Chemical extinction was ∼15% lower than optical extinction, but they were highly correlated. Elevated concentrations of secondary aerosol species (i.e.SO42- and NO3-) were the main causes of VR <5 Km.
KW - Chemical species
KW - Light extinction coefficient
KW - Source apportionment
KW - Visibility impairment
UR - https://www.scopus.com/pages/publications/84879755685
M3 - 会议稿件
AN - SCOPUS:84879755685
SN - 9781622768219
T3 - Air and Waste Management Association - Aerosol and Atmospheric Optics: Visibility and Air Pollution Specialty Conference 2012
SP - 75
EP - 79
BT - Air and Waste Management Association - Aerosol and Atmospheric Optics
T2 - Aerosol and Atmospheric Optics: Visibility and Air Pollution Specialty Conference 2012
Y2 - 25 September 2012 through 28 September 2012
ER -