谱线漂移对星载成像光谱仪辐射测量精度的影响

分析了谱线漂移在地面辐射定标、星上辐射定标和在轨对地观测等环节对成像光谱仪辐射测量的影响，建立了从实验室辐射定标到星上辐射定标再到在轨对地观测全过程的辐射传递模型，并通过仿真分析求解了成像光谱仪入瞳处辐射测量不确定与谱线漂移之间的关系。结果表明，谱线漂移导致的辐射测量误差与谱线漂移量和入瞳辐亮度的分布梯度成正比；光谱带宽偏差对测量精度的影响程度较中心波长误差高一个数量级。对于可见近红外(VNIR)波段平均光谱带宽10 nm、短波红外(SWIR)波段平均光谱带宽20 nm的典型成像光谱仪，要保证谱线漂移引起的辐射测量不确定度小于6%，实现成像光谱仪在轨观测时入瞳处的辐射测量绝对精度优于10%，可见近红外波段中心波长偏差应不大于2 nm，光谱带宽偏差应不大于0.1 nm，短波红外波段中心波长偏差应不大于3 nm，光谱带宽偏差应不大于0.1 nm。

Effect of Spectral-Line Shift on Radiometric Measurement Accuracy of Spaceborne Imaging Spectrometer

The effect of spectral-line shift on radiometric measurement accuracy of spaceborne imaging spectrometer during laboratory radiometric calibration, onboard radiometric calibration and onboard radiometric measurement is analyzed. Radiometric transmission model from laboratory radiometric calibration to onboard radiometric measurement has been established, and relationship between the uncertainty of radiometric measurement on entrance pupil and spectral-line shift is simulated. Results show that radiometric measurement error is linear to spectral-line shift and radiance distribution gradient on entrance pupil of imaging spectrometer. The radiometric measurement error caused by spectral width deviation is one order of magnitude larger than that caused by central wavelength deviation. For a typical imaging spectrometer 10 nm spectral width in visible near infrared spectroscopy (VNIR) band and 20 nm in shortwave infrared (SWIR) band], central wavelength deviation is less than 2 nm and spectral width deviation is less than 0.1 nm in VNIR band, or central wavelength deviation is less than 3 nm and spectral width deviation is less than 0.1 nm in SWIR band, which is necessary to ensure the uncertainty of radiometric measurement caused by spectral line-shift less than 6% and absolute accuracy of radiometric measurement on entrance pupil is superior to 10%.