北京沙尘天气期间气溶胶光学特性分析

利用全球地基气溶胶观测网(AERONET)资料,分析了北京地区2001—2013年沙尘天气期间气溶胶的光学特性。结果表明,北京沙尘天气期间受沙尘粒子的影响,气溶胶光学厚度值(AOD)较大,且随波长增大而减小,在波长440 nm处平均值约为1.2;气溶胶Angstrom波长指数97.62%都聚集在0.7以下,说明北京沙尘天气期间粒子较大;沙尘天气期间单次散射反照率随波长增加而增加,平均值约为0.93;复折射指数实部在波长675 nm处最大,平均约为1.55,虚部在440 nm处最大,平均值达到0.006;总的不对称因子平均值约为0.72;北京地区沙尘天气期间气溶胶粒子谱型呈双峰分布,且以粗模态粒子为主,其峰值随光学厚度的增大而增大,粗模态粒子的峰值半径平均约为2.6μm。这些参数对于深入研究沙尘气溶胶的辐射效应和气候效应都是必不可少的。

Optical Properties of Aerosol during the Dust Weather in Beijing

The global network of ground aerosol observation(AERONET)data was used to analyze the optical properties of aerosol during the dust weather in Beijing from 2001 to 2013.The results showed that account of the dust particles impaction during the dust weather in Beijing,the aerosol optical thickness(AOD)was large,which decreased with the wavelength increasing,and the average value was about 1.2 at the wavelength of 440 nm.97.62%of aerosol Angstrom exponent gathered below 0.7,indicating that the particles were large during the dust weather in Beijing.The single scattering albedo during the dust weather increased with the wavelength increasing,and the average value was about 0.93.The real part of the complex refractive index at the wavelength of 675 nm was the most,and the average was about 1.55,and the largest imaginary part was at the wavelength of 440 nm,reaching 0.006.The total asymmetry factor average was about 0.72.The aerosol volume size distribution was a bimodal distribution type during the dust weather in Beijing,mainly concentrated in coarse particles,and the main peak value increased with the aerosol optical thickness increasing,the average radius of the peak was about 2.6μm.All these parameters were essential for further study of the radiation effects and climatic effects of dust aerosol.