Toward High Precision XCO��� Retrievals From TanSat Observations: Retrieval Improvement and Validation Against TCCON Measurements
In: Journal of geophysical research / D, 125 (22), Art.: e2020JD032794; (2020)
Online
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Zugriff:
TanSat is the 1st Chinese carbon dioxide (CO$_{2}$) measurement satellite, launched in 2016. In this study, the University of Leicester Full Physics (UoL-FP) algorithm is implemented for TanSat nadir mode XCO$_{2}$ retrievals. We develop a spectrum correction method to reduce the retrieval errors by the online fitting of an 8th order Fourier series. The spectrum-correction model and its a priori parameters are developed by analyzing the solar calibration measurement. This correction provides a significant improvement to the O$_{2}$ A band retrieval. Accordingly, we extend the previous TanSat single CO$_{2}$ weak band retrieval to a combined O$_{2}$ A and CO$_{2}$ weak band retrieval. A Genetic Algorithm (GA) has been applied to determine the threshold values of post-screening filters. In total, 18.3% of the retrieved data is identified as high quality compared to the original measurements. The same quality control parameters have been used in a footprint independent multiple linear regression bias correction due to the strong correlation with the XCO$_{2}$ retrieval error. Twenty sites of the Total Column Carbon Observing Network (TCCON) have been selected to validate our new approach for the TanSat XCO$_{2}$ retrieval. We show that our new approach produces a significant improvement on the XCO$_{2}$ retrieval accuracy and precision when compared to TCCON with an average bias and RMSE of ���0.08 ppm and 1.47 ppm, respectively. The methods used in this study can help to improve the XCO$_{2}$ retrieval from TanSat and subsequently the Level-2 data production, and hence will be applied in the TanSat operational XCO$_{2}$ processing.
Titel: |
Toward High Precision XCO��� Retrievals From TanSat Observations: Retrieval Improvement and Validation Against TCCON Measurements
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Autor/in / Beteiligte Person: | Yang, D. ; Boesch, H. ; Liu, Y. ; Somkuti, P. ; Cai, Z. ; Chen, X. ; Di Noia, A. ; Lin, C. ; Lu, N. ; Lyu, D. ; Parker, R. J. ; Tian, L. ; Wang, M. ; Webb, A. ; Yao, L. ; Yin, Z. ; Zheng, Y. ; Deutscher, N. M. ; Griffith, D. W. T. ; Hase, F. ; Kivi, R. ; Morino, I. ; Notholt, J. ; Ohyama, H. ; Pollard, D. F. ; Shiomi, K. ; Sussmann, R. ; Té, Y. ; Velazco, V. A. ; Warneke, T. ; Wunch, D. |
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Quelle: | Journal of geophysical research / D, 125 (22), Art.: e2020JD032794; (2020) |
Veröffentlichung: | John Wiley and Sons, 2020 |
Medientyp: | unknown |
ISSN: | 2169-897X (print) ; 2169-8996 (print) |
DOI: | 10.5445/ir/1000126516 |
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