Vegetation-shadow indices based on differences in effect of atmospheric-path radiation between optical bands

International Journal of Applied Earth Observations and Geoinformation

Jia Tian¹  Nianxu Xu²  Jibo Yue³  Qingjiu Tian⁴ 

[1] International Institute for Earth System Science, Nanjing University, Nanjing 210023, China;Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, Nanjing University, Nanjing 210023, China;College of Information and Management Science, Henan Agricultural University, Zhengzhou 450002, China;International Institute for Earth System Science, Nanjing University, Nanjing 210023, China;

关键词: Shadows;    TOA reflectance;    Surface reflectance;    Optical remote sensing;    Vegetation-shadow indices;    Illumination conditions;   

DOI  :  

来源: DOAJ

【 摘 要 】

The fractional coverage of the illuminated vegetation (IV), illuminated soil (IS), shaded vegetation (SV), and shaded soil (SS) are four essential structural parameters (fIV, fIS, fSV, and fSS) describing the vegetation canopy. Their correct estimation can help improve the monitoring of vegetation growth. In this study, we propose and evaluate four coastal/aerosol-band-based vegetation-shadow indices (CVSIs) using the normalized difference of top-of-atmosphere (TOA) reflectance in the coastal/aerosol band and in the blue, green, red, and near-infrared (NIR) bands. We used the four CVSIs to evaluate the illumination conditions of the vegetation-soil canopy for two cases: shadows produced by vegetation and shadows produced by mountains. We also evaluated the combined use of linear spectral mixture analysis (LSMA), CVSIs, and the normalized difference vegetation index (NDVI) to estimate fIV, fIS, fSV, and fSS. The results led to several conclusions: (i) the effects of atmospheric path radiation mainly influence the optical bands, resulting in the coastal/aerosol-band TOA reflectance exceeding the TOA reflectance of the blue, green, red, and near-infrared bands; (ii) CVSIs can be used to evaluate the illumination conditions of the vegetation-soil canopy; (iii) the proposed strategy produces reasonably accurate estimates of fIV, fIS, fSV, and fSS (n = 191,268; R2 = 0.830–0.981; mean absolute error = 0.053–0.098; root mean square error = 0.063–0.126). Maps of fIV, fIS, fSV, and fSS are consistent with maps of the actual field illumination conditions.

【 授权许可】

Unknown