Tucker C J
Appl Opt. 1977 May 1;16(5):1151-6. doi: 10.1364/AO.16.001151.
The asymptotic nature of grass canopy spectral reflectance has been evaluated from field experimental data collected over the wavelength region of 0.500-1.000 microm at 0.005-microm intervals. The spectral reflectance of green vegetation against a soil background decreases in regions of absorption and increases in regions of minimal or no absorption as the vegetational density increases until a stable or unchanging spectral reflectance, called the asymptotic spectral reflectance, is reached. Results indicated spectral reflectance asymptotes occurred at significantly lower levels of total wet biomass, total dry biomass, dry green biomass, chlorophyll content, and leaf water content in regions of strong pigment absorption (low detectability threshold) than in the photographic ir region where absorption was at a minimum (high detectability threshold). These findings suggested that photographic ir sensors were more suited to remote sensing of moderate to high biomass levels or vegetational density in a grass canopy than were sensors operating in regions of the spectrum where strong absorption occurred.
已根据在0.500 - 1.000微米波长范围内以0.005微米间隔收集的野外实验数据，评估了草冠层光谱反射率的渐近性质。随着植被密度增加，绿色植被相对于土壤背景的光谱反射率在吸收区域降低，在最小吸收或无吸收区域增加，直至达到稳定或不变的光谱反射率，即渐近光谱反射率。结果表明，与吸收最小的摄影红外区域（高检测阈值）相比，在色素强烈吸收区域（低检测阈值），总湿生物量、总干生物量、干绿色生物量、叶绿素含量和叶片含水量显著较低时，光谱反射率渐近线就会出现。这些发现表明，与在光谱强吸收区域工作的传感器相比，摄影红外传感器更适合于遥感草冠层中、高生物量水平或植被密度。
