一种基于光谱库的雪粒径及形状参数反演新方法

雪粒径的形状因素对积雪的反射光谱曲线影响较大,如何有效地刻画雪粒径的形状参数成为研究的热点。渐进辐射传输模型被广泛地应用于雪粒径反演,其对雪粒径形状的描述只采用了2个值(3.62对应于片状雪粒径,4.53为球形雪粒径),较难描述积雪的形状参数,同时为了反演积雪的雪粒径,这两个形状参数必须被提前固定,这大大降低了雪粒径的反演精度,为此提出了一种基于光谱库的雪粒径及形状参数反演算法(LUTMA)。首先利用渐进辐射传输模型建立不同粒径,不同形状参数的光谱库,然后采用光谱角指标进行匹配,最终获取积雪的粒径与形状参数。实验表明,基于光谱库的雪粒径及形状参数反演新方法与实测数据较为吻合。

A Kind of Snow Grains and Shape Parameters Retrieval New Algorithm Based on Spectral Library

Snow grain sizes retrieval accuracy was affected by many factors wile snow shape was an important factor.Asymptotic radiative transfer (ART) model used a digital simulation and asymptotic technology to simplify radiative transfer models,which was widely used to reverse snow grain.ART model considered two snow shape parameters,which depended on the snow grain shape and asymmetry (considering 3.62 for fractal particles;and 4.53 for spheres particles).In reversing snow grain processing of ART,the shape parameters were determined beforehand,but in nature snow particles might take on different shapes,and ART couldn't accurately reverse snow grain sizes with single shape parameter.In order to accurately reverse snow grain sizes,snow grain sizes and shapeparameters must be obtained simultaneously.Based on ART model,a Look-Up-Table Minimal Angle model was proposed to solve the problem.The new model could obtain the shape parameter values and snow grainsizes simultaneously,solving the problem of determining shape parameter value beforehand,which determined the shape parameter values automatically.Experimental results showed that new model could accurately retrieve snow particle sizes,which were more consistent with field validation datas.