光谱响应差异对高精度交叉定标的影响——以FY-3A/MERSI与EOS/MODIS为研究实例

分析了MERSI与MODIS间光谱响应差异对测量表观反射比的影响。正演模拟结果显示,在极区冰雪情况下,MERSI与MODIS测量得到的表观反射比之间的相对差异是关于MODIS所测表观发射比的二次函数。MERSI的前4个通道与对应的MODIS通道之间的相对差异在0~0.8%,0~2%,0.5%~2.5%,-1.8%~-0.8%之间。将正演模拟得到的对光谱响应差异的修正关系应用到具体的SNO测量后,MERSI前3个通道的表观反射比与修正后MODIS的表观反射比之间的相对差异减小到了3%以内。MERSI的1、2通道在红外波段也有响应,这部分响应在极区冰雪条件下对表观反射率的影响在0.5%左右,基本可以忽略。

Impacts of Spectral Response Differences on SNO Calibration-study Examples of FY-3A/MERSI and EOS/MODIS

This paper analyzes the impacts of MERSI and MODIS spectral response differences on the measured apparent reflectance.Simulated result shows that the relative difference between MERSI and MODIS measurements in apparent reflectance is a quadratic function of MODIS apparent.The ranges of the relative difference in the first four bands of MERSI and the corresponding MODIS bands are about 0 - 0.8%,0 - 2%,0.5% - 2.5%,-1.8% - 0.8%.Modify functions which are regressed from the forward modeling results are then applied to the SNO measurements,the relative difference between MERSI first 3 bands and relevant MODIS bands reduced to within 3%.For MERSI Band 1 and Band 2,there is a bit of response in Near-infrared,the effects of these responses are about 0.5%,which can ignore their impacts in polar condition.