Preflight Spectral Calibration of the Orbiting Carbon Observatory

• Published in: IEEE transactions on geoscience and remote sensing 2011-07, Vol.49 (7), p.2793-2801
• Main Authors: Day, Jason O., O'Dell, C. W., Pollock, R., Bruegge, C. J., Rider, D., Crisp, D., Miller, C. E.
• Format: Article
• Language: English
• Subjects: Applied geophysics; Calibration; Carbon dioxide (\hbox{CO}_{2}); Detectors; Dispersion; Earth sciences; Earth, ocean, space; Exact sciences and technology; instrument line shape (ILS); Instruments; Internal geophysics; Lasers; Orbiting Carbon Observatory (OCO); Pixel; Polynomials; spectral calibration
• ISSN: 0196-2892; 1558-0644
• DOI: 10.1109/TGRS.2011.2107745

We report on the preflight spectral calibration of the first Orbiting Carbon Observatory (OCO) instrument. In particular, the instrument line shape (ILS) function as well as spectral position was determined experimentally for all OCO channels. Initial determination of these characteristics was conducted through laser-based spectroscopic measurements. The resulting spectral calibration was validated by comparing solar spectra recorded simultaneously by the OCO flight instrument and a collocated high-resolution Fourier transform spectrometer (FTS). The spectral calibration was refined by optimizing parameters of the ILS as well as the dispersion relationship, which determines spectral position, to yield the best agreement between these two measurements. The resulting ILS profiles showed agreement between the spectra recorded by the spectrometers and FTS to approximately 0.2% rms, satisfying the preflight spectral calibration accuracy requirement of better than 0.25% rms.