Effects of spectral sampling rate and range of CO2 absorption bands on XCO2 retrieval from TanSat hyperspectral spectrometer

• DOI: 10.1007/s11434-014-0215-8
• Publication Date: 2014-03-10T07:18:23Z
• Authors: Yi Liu; Zhaonan Cai; Dongxu Yang; Yuquan Zheng; Minzheng Duan; Daren Lü
• Keywords: 13. Climate action; 7. Clean energy; 01 natural sciences; 0105 earth and related environmental sciences

The spectral sampling rate and range of CO2 absorption bands are critical for the optimal design of hyperspectral instrument for CO2 observation satellite. Undersampling of spectra in space-based spectrometer significantly contaminates signals measured in the CO2 1.61 μm-band. The CO2 dry-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 retrieval 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.