影响黄土高原地物光谱反射率的非均匀因子及反照率参数化研究  

The relations of spectrum reflectance with inhomogeneous factors and albedo parameterization

作　　者：张杰[1] 张强[2] 

机构地区：[1]气象灾害省部共建教育部重点实验室,南京信息工程大学,南京210044 [2]中国气象局兰州干旱气象研究所,兰州730020

出　　处：《生态学报》2011年第24期7418-7427,共10页Acta Ecologica Sinica

基　　金：国家自然科学基金(4083095740805009)

摘　　要：通过应用高光谱反射仪进行各种植被覆盖度地物的同期观测,分析不同地物光谱反射率和宽波段反照率的差异,得出:除太阳高度角的影响外,植被的不同生育期及生长状况决定的叶绿素、细胞构造和含水量等要素都会影响植物光谱反射率;基于归一化植被指数(NDVI)、归一化植被水分指数(NDWI)、土壤体积含水量以及参考对象的光谱曲线建立了植物光谱反射率的估算模型,能较好地反映地物光谱反射率特征;基于地物波谱反射率估算得到的全波段反照率误差在0.02范围内,可以作为反照率遥感反演和转换的依据;该方法也为高光谱遥感在反照率等陆面过程参数尺度耦合和转换过程中应用奠定了基础。Remote sensing of albedo over inhomogeneous surfaces is an important topic that involves core problems such as assuring incidence angle,reflection angle and spectrum continuity.Hyper-spectral remote sensing is a good way to investigate the spectral continuity effect on albedo retrieval.In this research,synchronized observations of a wide range of soil and vegetative land cover were performed using the hyper-spectral instrument ASD FieldSpec Pro FRTM.Differences between spectral reflectance and broad albedo were analyzed.Spectral curves show that there are large differences at visible and near-infrared wavelengths;reflectance is low from 400 to 450 nm and from 650 to 700 nm due to strong chlorophyll absorption;reflectance is high,from 750 to 1300 nm due to cell structure reflectance;and reflectance is low from 1360 to1470 nm,1830 to 2080 nm,and 2350 to 2500 nm,due to water vapor absorption.In addition to the sun zenith angle,chlorophyll,the cell structure of vegetation and water content are shown to be the main factors affecting the spectral reflectance of underlying surfaces,which are determined by the different growth stages and conditions of the vegetation.Therefore,chlorophyll,the cell structure of vegetation and water content are considered to be the important distinguishing indices for describing the spectral reflectance of sparse vegetation and inhomogeneous surfaces.They can be described by the normal difference vegetation index（NDVI）,the normal difference vegetation water index（NDWI）,and the soil water content capacity（SWCC）,respectively. There is a good negative logarithmic relationship between albedo and SWCC when SWCC is larger than 0.2,and a negative logarithmic relationship and linearity between albedo and both NDVI and NDWI.Based on the relationships,an albedo retrieval model is estimated that relies on the reference spectral reflectance of the vegetation and soil.Spectral wavelengths between 0.3 and 2.35 μm are divided into 12 sections;the broad albedo is estimated by combining the 12

关 键 词：地表反照率 光谱反射率 尺度转换 归一化植被指数 归一化植被水分指数 非均匀地表 

分 类 号：TP79[自动化与计算机技术—检测技术与自动化装置]