Monitoring of atmospheric methane and nitrous oxide concentrations from Metop/IASI

Future of the Earth-atmosphere system will depend, to a large extent, on our capability of understanding all the processes driving climate change and, in this context, of outstanding importance are the monitoring and the investigation of greenhouse gases (GHGs), as main drivers of the Earth’s climate change. With this idea the project INMENSE (IASI for Surveying Methane and Nitrous Oxide in the Troposphere) was born, which aims to improve our current understanding of the atmospheric budgets of two of the most important well-mixed greenhouse gases, methane (CH 4 ) and nitrous oxide (N 2 O). To this end, INMENSE has generated a new global observational data set of middle/upper tropospheric concentrations of CH 4 and N 2 O from the space-based remote sensor IASI (Infrared Atmospheric Sounding Interferometer), on board the meteorological satellites EUMETSAT/Metop. In this work the INMENSE IASI CH 4 and N 2 O products are presented, characterized and comprehensively validated by using a multiplatform reference database (aircraft vertical profiles, ground-based in-situ and remote-sensing observations). This extensive validation exercise suggests that the IASI CH 4 and N 2 O products shows a precision between 1-3% and a bias of 2% as well as they are consistent temporally and spatially. Finally, the CH 4 and N 2 O IASI observations over the Iberian Peninsula have been compared to MOCAGE chemical transport simulations, assessing the degree of agreement between both datasets.