雪-土混合像元微观/宏观尺度光谱混合机制差异分析

Observations of Spectral Data and Characteristics Analysis of Snow-Bare Soil Mixed Pixel Generated by Micro-Simulation

为探索微观和宏观尺度下混合像元光谱混合机制的差异，在人工设置试验环境下，以人工制作雪-土混合像元表征微观尺度混合像元，固定全波段光谱仪探头距离，完成不同面积比的雪-土混合像元和雪、土端元反射光谱的采集，并对采集得到的光谱数据进行全波段反射光谱、350～2500 nm归一化反射光谱和剔除噪声后350～1815 nm再归一化反射光谱数据定性定量分析。同时，分析同期M ODIS和环境与灾害监测卫星B星（HJ-1B CCD/IRS）影像中可见光、近红外和短波红外通道反射率相关性及MODIS影像中雪-土混合像元光谱与端元光谱的关系。结果表明；（1）微观尺度时，全波范围内混合像元反射光谱与端元光谱存在非线性关系，分波段范围内存在线性关系；（2）宏观尺度时，可见光范围内，CCD 1，2，3通道与M ODIS 3，4，1通道相关系数在0.76～0.89间；短波红外范围内，IRS通道2与M ODIS通道6相关系数为0.35。（3）MODIS影像中雪-土混合像元光谱与端元光谱关系为混合像元与雪端元光谱间正线性相关，与裸土端元光谱负线性相关。

To explore the differences of mixed-pixel in spectral mixing mechanism at micro-and macro-scale ,the micro-simulation of snow-bare soil mixed pixel was taken as the object of study in an artificial test environment .Reflectance spectra of mixed pixel and snow ,bare soil endmember with different area ratio were collected by full-band spectrometer with fixed probe distance . Qualitative and quantitative analysis of original reflectance spectra was done ,and reflectance spectra form 350 to 2 500 nm and normalized reflectance spectral data of 350 to 1 815 nm excluding noise were normalized .At the same time ,we collected EOS/MODIS and Environment and Disaster Monitoring Satellites data of the same period over the same area and analyzed the correla-tion of channels in visible ,near-infrared and shortwave infrared wavelength range at different resolution scales and the relation-ship between spectrum of mixed snow-soil and endmember pixel in MODIS image was analyzed .The results showed that ,（1） At the micro scale ,non-linear relationship existed between mixed pixel and endmember within the scope of the full-wave and linear relationship existed in sub-band wavelength range ;（2） At the macro scale ,linear relationship existed between mixed pixel and endmember .（3） In statistics of spectral values ,the correlation between snow-soil mixture and endmember is positive for snow-soil mixture and snow endmember ,and is negative for snow-soil mixture and soil endmember .