Yu Xingna, Kumar K Raghavendra, Lü Rui, Ma Jia
Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, Jiangsu province, China.
Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, Jiangsu province, China.
Environ Pollut. 2016 Mar;210:217-26. doi: 10.1016/j.envpol.2015.12.021. Epub 2015 Dec 29.
Several dense haze-fog (HF) episodes were occurred in the North China Plain (NCP), especially over Beijing in January 2013 characterized by a long duration, a large influential region, and an extremely high PM2.5 values (>500 μg m(-3)). In this study, we present the characteristics of aerosol optical properties and radiative forcing using Cimel sun-sky radiometer measurements during HF and no haze-fog (NHF) episodes occurred over Beijing during 1-31 January, 2013. The respective maximum values of daily mean aerosol optical depth at 440 nm (AOD440) were observed to be 1.21, 1.43, 1.52, and 2.21 occurred on 12, 14 19, and 28 January. It was found that the Ångström exponent (AE) values were almost higher than 1.0 during all the days with its maximum on 26 January (1.53), suggests the dominance of fine-mode particles. The maximum (minimum) aerosol volume size distributions occurred during dense HF (NHF) days with larger particle volumes of fine-mode. The single scattering albedo, asymmetry parameter, and complex refractive index values during HF events suggest the abundance of fine-mode particles from anthropogenic (absorbing) activities mixed with scattering dust particles. The average shortwave direct aerosol radiative forcing (DARF) values at the bottom-of-atmosphere (BOA) during HF and NHF days were estimated to be 112.29 ± 42.18 W m(-2) and -58.61 ± 13.09 W m(-2), while at the top-of-atmosphere (TOA) the forcing values were -45.78 ± 22.17 W m(-2) and -18.64 ± 5.84 W m(-2), with the corresponding heating rate of 1.61 ± 0.48 K day(-1) and 1.12 ± 0.31 K day(-1), respectively. The DARF values retrieved from the AERONET were in good agreement with the SBDART computed both at the TOA (r = 0.95) and the BOA (r = 0.97) over Beijing in January 2013.
华北平原（NCP）出现了几次严重的雾霾（HF）天气过程，特别是在2013年1月的北京，其特点是持续时间长、影响区域大以及PM2.5值极高（>500 μg m(-3)）。在本研究中，我们利用Cimel太阳天空辐射计的测量数据，展示了2013年1月1日至31日在北京出现雾霾（HF）和无雾霾（NHF）天气过程期间气溶胶光学特性和辐射强迫的特征。在440 nm处的日平均气溶胶光学厚度（AOD440）的各自最大值在1月12日、14日、19日和28日分别观测到为1.21、1.43、1.52和2.21。发现在所有日子里，Ångström指数（AE）值几乎都高于1.0，在1月26日达到最大值（1.53），这表明细模态粒子占主导。最大（最小）气溶胶体积粒径分布出现在浓雾（HF）日，细模态粒子的体积更大。雾霾（HF）事件期间的单次散射反照率、不对称参数和复折射率值表明，来自人为（吸收性）活动的细模态粒子与散射尘埃粒子混合存在。雾霾（HF）日和无雾霾（NHF）日在大气底层（BOA）的平均短波直接气溶胶辐射强迫（DARF）值估计分别为112.29±42.18 W m(-2)和 -58.61±13.09 W m(-2)，而在大气顶层（TOA）的强迫值分别为 -45.78±22.17 W m(-2)和 -18.64±5.84 W m(-2)，相应的加热率分别为1.61±0.48 K day(-1)和1.12±0.31 K day(-1)。从AERONET获取的DARF值与2013年1月在北京大气顶层（TOA）（r = 0.95）和大气底层（BOA）（r = 0.97）计算的SBDART结果高度一致。
