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Amazon rainforest fires have significant environmental and societal impacts, but the mechanism and impact of the fires on the regional and global carbon cycles have not been fully understood. Over the rainforest, less precipitation, higher surface temperature, and enhanced mid‐tropospheric sinking air over the eastern part of the Amazon characterized the fire/dry season. These meteorological conditions will facilitate more fires in the Amazon rainforest. Using the Orbiting Carbon Observatory‐2 column CO2, we notice that there are ∼2 ppm more CO2 over the Amazon compared with the surrounding area during the fire season. The higher concentrations of atmospheric CO2 are related to the surface biomass burning, enhanced sinking air over the eastern part of the Amazon, and surface winds. Results from this study can help us better understand the carbon sources and sinks over the Amazon during the fire/dry season. Plain Language Summary: In this study, we explore the influence of fires on atmospheric CO2 over the whole Amazon region using satellite CO2 data. Our analysis not only reveals an increase in the CO2 concentration (∼2 ppm) over the Amazon during the fire season but also provides a possible mechanism to explain the increase. Our study further suggests that the Amazon forest changes from a CO2 sink to a CO2 source during the fire season. The increase in the CO2 can lead to a warmer climate and produce more fires. It is still a challenge for current models to simulate the impact of fires on atmospheric CO2 correctly, especially the interannual variability. Results in this study can help us better constrain models in the future. Key Points: CO2 concentrations are higher over the Amazon than the surrounding region during the fire/dry seasonHigh concentrations of CO2 are related to the biomass burning, enhanced sinking air, and surface windsAmazon forest changes from a CO2 sink to a CO2 source during the fire season [ABSTRACT FROM AUTHOR]

Amazon rainforest fires have significant environmental and societal impacts, but the mechanism and impact of the fires on the regional and global carbon cycles have not been fully understood. Over the rainforest, less precipitation, higher surface temperature, and enhanced mid‐tropospheric sinking air over the eastern part of the Amazon characterized the fire/dry season. These meteorological conditions will facilitate more fires in the Amazon rainforest. Using the Orbiting Carbon Observatory‐2 column CO2, we notice that there are ∼2 ppm more CO2 over the Amazon compared with the surrounding area during the fire season. The higher concentrations of atmospheric CO2 are related to the surface biomass burning, enhanced sinking air over the eastern part of the Amazon, and surface winds. Results from this study can help us better understand the carbon sources and sinks over the Amazon during the fire/dry season. Plain Language Summary: In this study, we explore the influence of fires on atmospheric CO2 over the whole Amazon region using satellite CO2 data. Our analysis not only reveals an increase in the CO2 concentration (∼2 ppm) over the Amazon during the fire season but also provides a possible mechanism to explain the increase. Our study further suggests that the Amazon forest changes from a CO2 sink to a CO2 source during the fire season. The increase in the CO2 can lead to a warmer climate and produce more fires. It is still a challenge for current models to simulate the impact of fires on atmospheric CO2 correctly, especially the interannual variability. Results in this study can help us better constrain models in the future. Key Points: CO2 concentrations are higher over the Amazon than the surrounding region during the fire/dry seasonHigh concentrations of CO2 are related to the biomass burning, enhanced sinking air, and surface windsAmazon forest changes from a CO2 sink to a CO2 source during the fire season [ABSTRACT FROM AUTHOR]