Detection of Anthropogenic CO₂ Emission Signatures with TanSat CO₂ and with Copernicus Sentinel-5 Precursor (S5P) NO₂ Measurements: First Results

China’s first carbon dioxide (CO₂) measurement satellite mission, TanSat, was launched in December 2016. This paper introduces the first attempt to detect anthropogenic CO₂ emission signatures using CO₂ observations from TanSat and NO₂ measurements from the TROPOspheric Monitoring Instrument (TROPOMI) onboard the Copernicus Sentinel-5 Precursor (S5P) satellite. We focus our analysis on two selected cases in Tangshan, China and Tokyo, Japan.We found that the TanSat XCO₂ measurements have the capability to capture the anthropogenic variations in the plume and have spatial patterns similar to that of the TROPOMI NO₂ observations. The linear fit between TanSat XCO₂ and TROPOMI NO₂ indicates the CO₂-to-NO₂ ratio of 0.8 × 10^–16 ppm (molec cm^–2)^–1 in Tangshan and 2.3 × 10^–16 ppm (molec cm^–2)^–1 in Tokyo. Our results align with the CO₂-to-NO_x emission ratios obtained from the EDGAR v6 emission inventory.