Globally standardized MODIS spectral mixture models
Globally standardized MODIS spectral mixture models
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全球标准化 MODIS 光谱混合模型
DOI：
10.1080/2150704x.2019.1634299
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发表时间：
2019
影响因子：
2.3
通讯作者：
C. Small
中科院分区：
文献类型：
--
作者：
D. Sousa;C. Small
本文介绍了用于MODIS第6版每日最低点观测BRDF调整反射率（每日NBAR）的光谱混合分析（SMA）的标准化基质、植被和暗（S、V和D）光谱端元（EM）。EM来自于跨越6大洲和所有非极地生物群落的超过43，000，000个MODIS光谱的多样化集合。EM光谱与来自十米研究的那些相似。使用351对27种EM组合进行的敏感性分析显示，SVD分数估计值的平均差异分别为4± 3%、3± 2%和3± 2%。一个额外的雪EM被确定，但被认为是暂时的，有待进一步的冰冻圈分析。与Landsat的替代验证显示，V部分的偏差低于0.5%，S和D部分的偏差为-7%和+11%，所有部分的分散度相当（标准差为6%至7%）。模型失配较低（99.9%像素的均方根误差低于5%）。当V与归一化差异、增强和土壤调整植被指数（NDVI、EVI、SAVI）相比时，NDVI显示出EVI和SAVI的两倍多的离散度（标准差29% vs 13-14%）和4倍多的偏差（+18% vs 4%）。结合前人的研究，这些结果将全球SVD线性混合模型的标度线性和低错配从2 m扩展到500 m。
ABSTRACT Standardized substrate, vegetation, and dark (S, V, & D) spectral endmembers (EMs) are presented for spectral mixture analysis (SMA) of MODIS version 6 daily nadir looking BRDF-adjusted reflectance (daily NBAR). EMs are derived from a diverse collection of over 43,000,000MODIS spectra spanning 6 continents and all non-polar biomes. EM spectra are similar to those from decametre studies. Sensitivity analysis using 351 pairs of 27 EM combinations shows mean differences in SVD fraction estimates of 4±3%, 3±2%, and 3±2%, respectively. An additional snow EM is identified, but deemed tentative pending further cryospheric analysis. Vicarious validation with Landsat shows under 0.5% bias in V fraction, −7% and +11% biases in S and D fractions, and comparable dispersion (standard deviation 6% to 7%) in all fractions. Model misfit is low (root-mean-square error under 5% for 99.9% pixels). When V is compared to Normalized Difference, Enhanced, and Soil Adjusted Vegetation Indices (NDVI, EVI, SAVI), NDVI shows over twice the dispersion (standard deviation 29% vs 13–14%) and over 4 times the bias (+18% vs 4%) of EVI and SAVI. Combined with previous studies, these results extend the scaling linearity and low misfit of the global SVD linear mixture model from 2m up to 500m.