# AB2CD: AirBorne Campaign for Carbon Dioxide ## Scientific objectives ESA 2014 Science Strategy for Earth Observation has stated the need to identify how lidar techniques can fill in the main knowledge and observational gaps in our current understanding of anthropogenic greenhouse gas budget (especially carbon dioxide and methane). The two main technical questions that will be addressed by AB2CD are: - What a unique combination of airborne active instruments measuring CO2 columns and wind profile brings to the knowledge of CO2 emissions at the surface? - Can the combination of airborne active and in-situ measurements efficiently contribute to the validation of satellite sensors and support their measurement capability? ## The location The AB2CD campaign targets 4 sites: Madrid, Barcelona, Bilbao and Fos-sur-mer. They have been chosen to maximize fair weather in October, as well as ensuring a scale of CO2 emissions over which to evaluate the capability of AB2CD instrumentation to infer these emissions. Madrid, Barcelona and Bilbao are among the largest cities of Spain and, as such, display emissions of CO2, CH4 and other atmospheric pollutants. In recognition of this, specific urban networks for greenhouse gas (GHG) monitoring are being implemented in Madrid and Barcelona, with several sites equipped with Picarro CRDS analysers and EM27/SUN Fourier Transform Spectrometers. AB2CD relies on these ground-based networks to gather external reference data. Fos-sur-mer is located in the South-West of France. The Gulf of Fos-sur-mer is home to one of Europe's largest industrial zones, with around thirty sites classified as Seveso 2 (hazardous activities). Among the multinationals present are Total, Esso, Gaz de France, Air Liquide, Kem One and ArcelorMittal. It makes it thus a designated target for AB2CD. ## The team ::::{card-carousel} 2 :::{card} Safire team  ::: :::{card} Gerfaut team  ::: :::: *Safire team on the left image and Gerfaut team on the right image* All together, the campaign involves 8 teams from 5 countries: - [LMD/Polytechnique Solutions (France)](https://www.lmd.ipsl.fr) - [DLR (Germany)](https://www.dlr.de/en/pa/about-us/departments/lidar) - [ONERA (France)](https://www.onera.fr/fr/dota-optique-et-techniques-associees) - [SAFIRE (France)](https://www.safire.fr/en) - [Gerfaut (France)](https://www.gerfautsystems.com/gerfaut) - [AEROLAB (France)](https://www.aerolab-innovation.com/) - [GHGSat (Canada)](https://www.ghgsat.com/) - [AEMET (Spain)](https://www.aemet.es/fr/eltiempo/prediccion) ## The instruments Three research aircrafts are deployed during the AB2CD campaign. SAFIRE (CNRS/CNES/Météo-France) ATR42 carries two innovative lidar instruments that are at the core of AB2CD objectives: DLR CHARM-F, a DIAL lidar for CO2 and CH4, and ONERA LiVe wind profiling instrument. The combination of these two active instruments should provide a direct estimate of surface emissions of the gases. In addition, a Picarro G2401 CRDS analyzer performs measurements of CO2, CH4, CO and H2O at the altitude of the aircraft. The Gerfaut Dynamic WT9 aircraft, named F-JHGS, is deployed at Madrid and Bilbao. It carries a Picarro G2401 CRDS analyzer to perform measurements of CO2, CH4, CO and H2O in the boundary layer. The Vulcanair P68, based in Madrid, carries GHGSat-AV CH4 spectro-imager. Measurement strategy includes raster patterns above the cities and specific source locations (industries, landfills, waste water management), up-wind and down-wind measurements, as well as long range satellite along-track flights.