EGU2020-17522
https://doi.org/10.5194/egusphere-egu2020-17522
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Toward high precision XCO2 retrievals from TanSat observations

Hartmut Boesch1, Dongxu Yang2, Yi Liu2, and Peter Somkuti3
Hartmut Boesch et al.
  • 1University of Leicester, Physics and Astronomy, Leicester, United Kingdom of Great Britain and Northern Ireland (hb100@le.ac.uk)
  • 2Institute of Atmospheric Physics, Chinese Academy of Sciences, China
  • 3Colorado State University, Fort Collins, CO, USA

TanSat is the 1st Chinese carbon dioxide measurement satellite, launched in 2016. Preliminary TanSat XCO2 retrievals have been introduced in previous studies based on the 1.6 m weak CO2 band. In this study, the University of Leicester Full Physics (UoL-FP) algorithm is implemented for TanSat nadir mode XCO2 retrievals. We develop a spectrum correction method to reduce the retrieval errors by an online fitting of an 8th order Fourier series. The model and a priori is developed by analyzing the solar calibration measurement. This correction provides a significant improvement to the O2 A band retrieval. Accordingly, we extend the previous TanSat single CO2 weak band retrieval to a combined O2 A and CO2 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. The same quality control parameters have been used in the bias correction due to the stronger correlation with the XCO2 retrieval error. A footprint independent multiple linear regression is applied to determine the sounding XCO2 retrieval error and bias correction. Twenty sites of the Total Column Carbon Observing Network (TCCON) have been selected to validate our new approach of the TanSat XCO2 retrieval. We show that our new approach produces a significant improvement of the XCO2 retrieval accuracy and precision when compared with TCCON with an average bias and RMSE of -0.08 and 1.47 ppm respectively. The methods used in this study, such as continuum correction, can help to improve the XCO2 retrieval from TanSat and subsequently the Level-2 data production, and hence will be applied in the TanSat operational XCO2 processing.

How to cite: Boesch, H., Yang, D., Liu, Y., and Somkuti, P.: Toward high precision XCO2 retrievals from TanSat observations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17522, https://doi.org/10.5194/egusphere-egu2020-17522, 2020

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