南京北郊地区黑碳气溶胶对光解系数的影响

Study on the influence of black carbon aerosol on photolysis coefficient in northern suburb of Nanjing

采用2018年6月以及2017年10月南京黑碳气溶胶(BC)垂直观测数据和Mie散射理论计算BC光学厚度(AODBC),并将结果输入TUV辐射传输模型,探讨BC对光解系数J[O1D]和J[NO2]日变化及垂直变化的影响.结果表明,在地面,J[O1D]和J[NO2]日变化均呈单峰型分布,峰值在正午12:00,但BC对J[O1D]和J[NO2]的衰减作用正午时最小,在6:00和18:00左右较大,最大分别可达?13.7%和?19.0%.AODBC与光解系数呈非线性负相关,BC对光解系数的衰减能力随着AODBC增大而下降.当天顶角为0?时,光解系数对AODBC的变化最敏感.在边界层0~1km内,光解系数与高度呈线性正相关,这与紫外辐射密切相关,J[O1D]和J[NO2]在垂直高度上与紫外辐射的相关系数R均高达0.99.BC对光解系数的衰减程度随高度下降而增大,但幅度较小,距平的最大值仅0.1%.

The optical depth of black carbon(AODBC)was calculated by Mie scatteringtheory and vertical observation data of black carbon aerosol(BC)in Nanjing in June 2018 and October 2017,which was taken as the input parameters of Tropospheric Ultraviolet and Visible radiation model(TUV)to studyeffect of BC on the diurnal and vertical variations of photolysis frequencies(J[O1D]andJ[NO2]).At 12:00 noon,the diurnal variation of photolysis frequencies had one peaking on the ground,but the attenuation of photolysis frequencies by black carbon(BC)were minimal.Then the maximum attenuation of J[O1D]and J[NO2]were-13.7%and-19.0%at 6:00 and 18:00.The relationshipbetween AODBC and photolysis frequencies was nonlinear,and the attenuation ability of BC to photolysis frequencies decreasedwith the increase of AODBC.When the value of solar zenith angle was 0°,photolysis frequencies were most sensitive to AODBC.In the boundary layer(0~1km),photolysis frequencies had a positive linear relationship with height,which was closely related to vertical variation of ultraviolet radiation,and the correlation coefficient(R)between it and photolysis frequencies was as high as 0.99.The attenuation degree of BC on photolysis frequencies increased with the decrease of height,but the vertical variation of it was very small and the maximum value of anomaly was only 0.1%.