高光谱遥感器通道中心波长漂移对红边光谱的影响

Influence of Channel Center Wavelength Shift of the Hyperspectral Remote Sensor on Red Edge Spectra

通过模拟高光谱遥感器通道中心波长漂移前后的典型植被红边区间反射率,定量分析通道中心波长漂移对红边光谱的影响。结果表明,通道中心波长漂移导致植被红边区间反射率曲线出现多处尖峰、抖动,使植被反射率曲线在本不具有特征吸收的区域变得不光滑,并与红边位置误差呈显著线性关系,决定系数R^(2)达到0.99。10 nm分辨率的高光谱遥感器,存在1,3,5 nm的通道中心波长漂移量时,给植被红边区间反射率造成的最大误差分别为1.46%、4.49%和9.57%,所获取的植被红边将分别"蓝移"0.75,2.60,5.52 nm。通道中心波长漂移会导致红边伪漂移,或对植被受胁迫引发的红边漂移造成"掩盖"或"强化"效应,进而影响基于高光谱遥感数据的植被受胁迫状态等指标的监测精度。高光谱遥感器通道中心波长漂移是红边漂移不可忽视的来源,精确的光谱定标是植被红边光谱相关定量化应用的重要基础。

We simulated the reflectance of typical vegetation in the red-edge region before and after the channel center wavelength shift of hyperspectral remote sensors to quantitatively examine the effect of the channel center wavelength shift on the red edge spectra. The results show that the channel center wavelength shift leads to many "spike" and "shake" phenomena in the reflectance curves of the red-edge region, and the reflectance curves in the region without characteristic absorption become unsmooth. Moreover, there is a significant linear relationship between the channel center wavelength shift and the red edge position(REP) error(coefficient of determination R^(2)=0.99). For a 10 nm hyperspectral remote sensor, when the channel center wavelength shifts are 1 nm, 3 nm, and 5 nm, the maximum errors in red-edge reflectance are 1.46%, 4.49%, and 9.57%, respectively, and the red edge spectra have the obvious "blue shift" phenomenon, with the REP shifting by 0.75 nm, 2.60 nm, and 5.52 nm, respectively. The channel center wavelength shift will lead to the pseudo-shift of the red edge or cause the "covering" or "strengthening" effect on the red edge shift induced by vegetation stress, which will directly affect the monitoring accuracy of vegetation stress based on hyperspectral remote sensing data. Channel center wavelength shift is an important source of the red edge shift. Accurate spectral calibration is the important basis of quantitative application related to the red edge spectra of vegetation.