Air pollution poses severe risks to our health due to a wide range of emissions of harmful substances and due to the induced climate change. The challenges we face are huge, multi-disciplinary and require major efforts for our societies and our economies. When developing mitigation strategies, all starts with a survey of our current emissions of air pollutants and a setup of a system monitoring trace gas emissions over the next decades. The European Union’s Copernicus programme includes four Sentinel missions dedicated to atmospheric monitoring, the Sentinel-5 Precursor (S5-P), Sentinel 4 and 5 (S4 and S5), and the recently selected CO2 monitoring mission CO2M. Our presentation gives an overview of the current status of the different missions, achievements using recent S5-P data and challenges for future data interpretation.

With the launch in the year 2017, S5-P gives us an impression of the unique observation possibilities of the atmospheric Sentinel missions. In a low earth orbit at about 800 km above ground, S5-P observes the vertically integrated amount of a suite of trace gases including NO2, O3, SO2, CH2O, CO and CH4 with daily global coverage. With a ground resolution of 3.5´5.5 km2 in the visible and 7´7 km2 in the shortwave infrared spectral range, the mission can not only observe regional enhancement of gases but also detects anomalies in the atmospheric concentration because of localized emission sources. S5-P data teaches us how to use spectral imaging data and gives us a novel view on anthropogenic and natural emissions. The successor S5 will continue this observation strategy, which will be complemented by S4 with hourly data on tropospheric constituents over Europe. Lastly, in summer 2020 the CO2 monitoring mission was selected by ESA for implementation. A novel instrument suite will allow to observe single CO2 emission events by power plants and so will be used to help track and implement targets set out in the Paris Agreement. Overall, the four missions S5-P, S4,S5 and CO2M are conceived as complementary elements of a constellation serving the specific needs of the Copernicus Atmospheric Monitoring Service (CAMS), which put Europe in the driving seat to play one of the key roles in atmospheric trace gas monitoring.