Technical Note on Quality Assessment for TANSAT

This document presents the assessment results of Chinese TANSAT Mission data. The Carbon Dioxide Monitoring Scientific Experimental Satellite (TanSat) was China’s firstdedicated greenhouse gas monitoring mission. Launched on 22nd December 2016, TanSat wastasked with measuring the CO2 concentration in the Earth’s atmosphere across the globe.Equipped with the Atmospheric Carbon dioxide Grating Spectrometer (ACGS), TanSat performednadir and glint observations of the Earth’s surface, recording the spectral signature of reflectedsunlight in three different wavebands: the O2A band (0.76 μm), the weak CO2 band (1.61 μm), andthe strong CO2 band (2.06 μm). Combined with a priori information, this data is used by retrievalalgorithms to infer the total CO2 column along the line of sight. This is then converted into a dry-aircolumn averaged mole fraction (XCO2). This study focuses on detailing the methodology behind the UoL-FP/IAPCAS retrievals and providing comparisons between TanSat UoL-FP/IAPCAS retrievals to TCCON. This work, in addition to presenting a comparison with TCCONdata, is also focused on Objectives 2, 3, and 4 comparing global, land-based XCO2 retrievals fromUol-FP to that of IAPCAS, between retrievals from IAPCAS to model XCO2 values from CAMS, andbetween retrievals from UoL-FP to model XCO2 values from CAMS. The work in this study is alsocoincident with another project by the European Space Agency (ESA) called the Climate ChangeInitiative + (CCI+). While the data spans a total of 416 days from March 2017 to May 2018, wepresent results for nine months of this spanning March 2017 to November 2017.