基于飞机观测不同天气条件下北京地区黑碳气溶胶的垂直分布及其混合态特性

Vertical distribution and mixed state characteristics of black carbon aerosols in Beijing Area based on aircraft observation under different weather conditions

利用机载单颗粒黑碳光度计(SP2)针对北京地区不同天气条件下黑碳(BC,black carbon)气溶胶的垂直分布特征进行了10次的飞机探测研究。结果显示,在霾和非霾条件下BC气溶胶的浓度都是随着高度升高而减小,而且浓度变化在1500 m高度存在明显的分界线。在1500 m以下,BC气溶胶浓度变化梯度均较大,霾条件下的BC气溶胶浓度约为非霾条件下的4.3倍,在1500 m以上,BC气溶胶浓度变化梯度均较小,霾条件下的BC气溶胶浓度约为非霾条件下的2.5倍。BC气溶胶粒子谱都呈单峰分布,霾条件下峰值粒径主要要集中在0.16µm在非霾条件下峰值粒径主要集中在0.18µm在近地面,霾条件下的平均内混比远远高于非霾条件下,越往高空两种条件下的BC气溶胶的平均内混比越接近。通过CAMx模拟了不同条件下的BC气溶胶,发现霾污染天气下模拟的结果差异较大,在非霾条件下的模拟结果要优于霾条件下的模拟结果,这主要是由于在大部分模式中,很少考虑黑碳的老化状态。

The airborne single particle soot photometer(SP2)was used in ten times of aircraft observation studies on vertical distribution characteristics of black carbon aerosol under different weather conditions in Beijing.The results showed that,under both haze and non-haze conditions,the concentration of black carbon aerosol decreased with the increase of the height,and there existed a clear boundary line for concentration change at the height of 1500 m.Below the height of 1500 m,the gradient of BC aerosol concentration was large,and the BC aerosol concentration under haze conditions was about 4.3 times of that under non-haze conditions.Above the height of 1500 meters,the gradient of BC aerosol concentration was small,and the BC aerosol concentration under haze conditions was about 2.5 times of that under non-haze conditions.It was also found that the BC aerosol particle spectrum had a single peak distribution,with the peak particle size mainly concentrated at 0.16µm under haze conditions,and 0.18µm under non-haze conditions.If close to the ground,the average internal mixing ratio under haze conditions was much higher than that under non-haze conditions,yet the average internal mixing ratios of BC aerosol under these two conditions become closer as the altitude gets higher.Additionally,via simulation by CAMx of the BC aerosols under different conditions,it was found that the simulated effects under haze condition were quite different,and the simulation results under non-haze conditions were better than that under haze conditions,which was mainly due to the fact that the aging state of black carbon was rarely considered in most modes.