摘要
引入了一个辐射加权平均的宽带气溶胶一次散射反照率(SSA)的定义,提出了一个从宽带的漫射信息反演该SSA的方法。数值模拟结果表明,在Junge气溶胶谱分布情形下,对气溶胶光学厚度、ngstr m指数与气溶胶虚部的通常变化范围,应用该SSA所计算的2160组宽带太阳辐射反射率、漫射透过率、总透过率和吸收率的相对标准误差都在1.107%以内;绝对标准差在0.00287以内。对非Junge的大陆性和都市工业污染气溶胶模式(由水溶性、沙尘和碳粒子组成),在72组反射率、漫射透过率、总透过率和吸收率计算中,相对标准差都在2.047%以内,绝对标准差在0.0075以内。在Junge气溶胶假设下,作者提出了一个综合应用宽带太阳直射和漫射信息同时反演气溶胶光学厚度与辐射加权平均SSA的方法,并通过模拟反演分析了SSA反演的3个主要误差因子。从反演结果可以看出:(1)如果ngstr m指数误差在±0.2以内,对0.55μm气溶胶光学厚度大于0.312大陆性气溶胶,SSA误差在±0.0418以内;(2)波长无关的宽带地表反照率适用于SSA反演;(3)气溶胶光学厚度越大,辐射资料误差所引起的SSA解误差越小。当辐射误差在±2%以内以及0.55μm气溶胶光学厚度大于0.312时,SSA解的误差在±0.0149以内;辐射误差在±4%以内时,SSA解的误差在±0.0317以内。
In this paper, radiation-weighted mean single scattering albedo （SSA） and A^°ngstroem index are introduced, and a method to retrieve the SSA from broadband solar diffuse radiation is presented. As shown in 2160 sets of numerical simulations, in the case of the Junge aerosol size distribution and for the usual aerosol optical thickness, A^°ngstroem index and imaginary part of aerosol refractive index, relative standard errors in broadband solar reflectance, diffuse transmittance, total transmittance and absorption calculations using the SSA are all within 1. 107%, and their absolute standard errors within 0. 00287. For non-Junge continent and urban-industrial aerosols （composed of water-soluble, dust-like and soot particles）, relative and absolute standard errors among 72 sets of reflectance, transmittance and absorption calculations using the SSA are within 2. 047 % and 0. 0075, respectively. Under an assumption of the Junge aerosol, a method to simultaneously retrieve aerosol optical thickness （AOT） and the radiation-weighted mean SSA is proposed using both broadband solar direct and diffuse radiations. Furthermore, the three main error factors of the SSA retrievals are analyzed through retrieval simulations. According to the retrieval results, three conclusions are obtained. At first, if the error of AngstrOm index is within ±0.2 and 0. 55 μm-wavelength AOT is larger than 0. 312, errors of the SSA retrievals are within ±0. 0418 for the continent aerosol. Secondly, the wavelength-independent broadband surface albedo is suitable for the SSA retrievals. Thirdly, the larger aerosol optical thickness is, the smaller the error of the SSA solution caused by the error of radiation data. Under the condition of 0. 55 μm-wavelength aerosol optical thickness being larger than 0. 312, the errors of SSA solutions are within ±0. 0149 and ±0. 0317 if radiation data errors are within ±2% and ±4%, respectively.
出处
《大气科学》
CSCD
北大核心
2006年第5期767-777,共11页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金资助项目40333029
关键词
宽带漫射辐射法
辐射加权平均一次散射反照率
反演误差
broadband diffuse radiation method, radiation-weighted mean single scattering albedo, retrieval error
