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The spectral sampling rate and range of CO2absorption bands are critical for the optimal design of hyperspectral instrument for CO2observation satellite.Undersampling of spectra in space-based spectrometer significantly contaminates signals measured in the CO21.61 lm-band.The CO2dry-air column(XCO2)error due to spectral undersampling can be up to*1 ppm,which is the target precision of the Chinese Carbon Satellite(TanSat)for a single sounding.Undersampling error depends on surface albedo,solar zenith angle,and scattering properties in the atmosphere.The spectral sampling rate is recommended to be greater than 2.0 pixels per full width at half maximum to avoid undersampling.Reduction of spectral resolution and the use of narrower spectral regions can improve spectral sampling with little changes in CO2retrieval sensitivity without losing much information.The full-band approach provides direct constraints on the wavelength-dependent surface albedo and particle scattering from the measurements.To keep a broader band,we recommend reduction of the spectral resolution by a factor of two.
The spectral sampling rate and range of CO2absorption bands are critical for the optimal design of hyperspectral instrument for CO2observation satellite. Uniting of spectra in space-based spectrometer significantly contaminates signals measured in the CO21.61 lm-band.The CO2dry-air column (XCO2 ) error due to spectral undersampling can be up to * 1 ppm, which is the target precision of the Chinese Carbon Satellite (TanSat) for a single sounding. Undersampling error depends on surface albedo, solar zenith angle, and scattering properties in the atmosphere. The spectral sampling rate is recommended to be greater than 2.0 pixels per full width at half maximum to avoid undersampling. Reduction of spectral resolution and the use of narrower spectral regions can improve spectral sampling with little changes in CO2 depletion sensitivity without losing much information. -band approach provides direct constraints on the wavelength-dependent surface albedo and particle scattering from the measurem ents.To keep a broader band, we recommend reduction of the spectral resolution by a factor of two.