天空辐射计观测2006年春季北京地区气溶胶光学特性的研究

摘要

利用2006年3～5月天空辐射计观测数据反演得到北京地区春季大气气溶胶光学性质参数,包括大气气溶胶光学厚度(0.5 μm)、Angstr(o)m指数、单次散射反射比和粒子谱分布特征.结果表明:北京地区春季气溶胶平均光学厚度0.67,Angstr(o)m指数0.54,单次散射比0.88,粒子吸收性质较弱,粒子谱呈双峰形,以粗粒子为主,粗、细模态粒子粒径分别集中在0.17μm和7.7μm左右.相比2004年此次观测期间气溶胶粒径较大,粒子体积浓度较高,散射作用在其消光特性中的比重略有下降.光学厚度日变化呈单峰型,日间单次散射比随时间逐渐递减,Angstr(o)m指数在上午递减趋势明显,午后变得稳定.对同时观测的天空辐射计与CE-318不同波长光学厚度结果进行比较,结果显示两者得到的光学厚度相关性很好,各波长小时平均结果的相对误差小于7％.%A ground-based skyradiometer was used to measure the direct and diffuse solar irradiances, as well as aureole radiances, from Mar to May 2006 over Beijing. The aerosol optical depth (AOD), Angstrom exponent (a) , Single Scattering Albedo (SSA), and volume size distributions of aerosols were retrieved The results indicated that the mean aerosol optical depth at 0. 5 μrn [AOD (0. 5 μm)], Angsrom exponent, and SSA (0. 5 μm) in spring over Beijing were 0. 67, 0. 536, and 0. 876, respectively. The aerosol volume size distributions presented a bimodal structure: A coarse mode with a radius of about 7. 7 μm and a fine mode with a radius of about 0. 17 μm, and the latter volume concentration is higher. Compare with the results of 2004, the volume of coarse particles was higher which caused by frequently dust storm in 2006 and the SSA was lower which meant higher percentage of absorptive particles. The diurnal variability of AOD was controled by human avtivity and air turbulence which reaced the peak value from 1100 LST to 1400 LST. The single scattering and Angstrom exponent was decrease with time, which indicated that the anthropologic aerosol was weak scattering and the coarse mode paricle number was growing in day time. The difference between skyradiometer and CE-318 was less than 7% for the AOD.