On-Orbit Characterization of TanSat Instrument Line Shape Using Observed Solar Spectra

doi:10.3390/rs14143334

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	On-Orbit Characterization of TanSat Instrument Line Shape Using Observed Solar Spectra
	Z. N. Cai; K. Sun; D. X. Yang; Y. Liu; L. Yao; C. Lin and X. Liu
	2022
发表期刊	Remote Sensing
卷号	14 期号:14 页码:14
摘要	The Chinese carbon dioxide measurement satellite (TanSat) has collected a large number of measurements in the solar calibration mode. To improve the accuracy of XCO2 retrieval, the Instrument Line Shape (ILS, also known as the slit function) must be accurately determined. In this study, we characterized the on-orbit ILS of TanSat by fitting measured solar irradiance from 2017 to 2018 with a well-calibrated high-spectral-resolution solar reference spectrum. We used various advanced analytical functions and the stretch/sharpen of the tabulated preflight ILS to represent the ILS for each wavelength window, footprint, and band. Using super Gaussian+P7 and the stretch/sharpen functions substantially reduced the fitting residual in O-2 A-band and weak CO2 band compared with using the preflight ILS. We found that the difference between the derived ILS width and on-ground preflight ILS was up to -3.5% in the weak CO2 band, depending on footprint and wavelength. The large amplitude of the ILS wings, depending on the wavelength, footprint, and bands, indicated possible uncorrected stray light. Broadening ILS wings will cause additive offset (filling-in) on the deep absorption lines of the spectra, which we confirmed using offline bias correction of the solar-induced fluorescence retrieval. We estimated errors due to the imperfect ILS using simulated TanSat spectra. The results of the simulations showed that XCO2 retrieval is sensitive to errors in the ILS, and 4% uncertainty in the full width of half maximum (FWHM) or 20% uncertainty in the ILS wings can induce an error of up to 1 ppm in the XCO2 retrieval.
DOI	10.3390/rs14143334
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收录类别	sci ; ei
语种	英语
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文献类型	期刊论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/66937
专题	中国科学院长春光学精密机械与物理研究所
推荐引用方式 GB/T 7714	Z. N. Cai,K. Sun,D. X. Yang,et al. On-Orbit Characterization of TanSat Instrument Line Shape Using Observed Solar Spectra[J]. Remote Sensing,2022,14(14):14.
APA	Z. N. Cai,K. Sun,D. X. Yang,Y. Liu,L. Yao,&C. Lin and X. Liu.(2022).On-Orbit Characterization of TanSat Instrument Line Shape Using Observed Solar Spectra.Remote Sensing,14(14),14.
MLA	Z. N. Cai,et al."On-Orbit Characterization of TanSat Instrument Line Shape Using Observed Solar Spectra".Remote Sensing 14.14(2022):14.

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