Global XCO₂ anomalies as seen by Orbiting Carbon Observatory-2

Abstract. NASA's carbon dioxide mission, Orbiting Carbon Observatory-2, has been operating for three full years (2015–2017). Here, we provide a global (60° S–60° N) view of the XCO₂ anomalies along with their annual variations and seasonal patterns. We show that the XCO₂ anomaly patterns are robust and consistent from year-to-year. We compare these anomalies to fluxes from anthropogenic, biospheric and biomass burning and to model-simulated local concentration enhancements. We find that, despite the simplicity of the method, the anomalies describe the spatio-temporal variability of XCO₂ (including anthropogenic emissions and seasonal variability related to vegetation and biomass burning) consistently with more complex model-based approaches. We see, for example, that positive anomalies correspond to fossil fuel combustion over the major industrial areas (e.g., China, eastern USA, central Europe, India, and the Highveld region in South Africa), shown as large positive XCO₂ enhancements in the model simulations. Also, we find corresponding positive anomalies and fluxes over biomass burning areas during different fire seasons. On the other hand, the largest negative anomalies correspond to the growing season in the northern middle latitudes, characterized by negative XCO₂ enhancements from simulations and high SIF values (indicating the occurrence of photosynthesis). Finally, we show how XCO₂ anomalies facilitate the detection of anthropogenic signatures for several local scale case studies, both in the Northern and Southern Hemisphere. The results demonstrate the potential of satellite-based XCO₂ observations for understanding the role of man-made and natural contributions to the atmospheric CO₂ levels.