DACCIWA was a large multi-national (Germany: KIT, DLR; France: CNRS, Université Blaise Pascal Clemont-Ferrand II, Université Paris Didertot, Université Paul Sabatier Toulouse III, Université Pierre et Marie Curie; UK: Met Office, University of Manchester, University of Leeds, University of York, University of Reading; Switzerland: ETH Zürich; European: ECMWF; Ghana: KNUST; Nigeria: Obafemi Awolowo University) project funded by the European Union 7th Framework Programme to investigate atmospheric processes over West Africa, ranging from the impact of air pollution on atmospheric health to the future climate of the region. Arranged around seven interlinking work packages (WP1: boundary layer dynamics; WP2: air pollution and health; WP3: atmospheric chemistry; WP4: cloud-aerosol interactions; WP5: radiative processes; WP6: radiative processes; WP7: precipitative processes; WP7: monsoon processes), the project aims to improve our scientific understanding of this region and its resilience through increased scientific understanding of key atmospheric processes.

The summer of 2016 was the focal point for the experimental activities. Highly instrumented supersites at Savé in Benin and Kumai in Ghana provided multi-week analysis of a range of meteorological parameters and targeted cloud formation, low-level jet activation, and precipitation formation. Meteorological sondes were released at regular intervals and as special observing periods from a range of cities in the region. Air quality measurements in the cities of Cotonou, Abidjan, and Akouedou provided information on pollution loads in regional cities and emission factors for emission estimates. Three research aircraft (DLR Falcon, BAS Twin Otter, SAPHIRE ATR43) were based in Lomé, Togo, for a month to make a range of observations over the coastal cities of Ivory Coast, Ghana, Togo, and Benin and inland over the rainforest, agricultural, and residential areas. The aircraft were equipped to measure a range of gas, aerosol, and meteorological parameters. A more complete list of payloads, observations collected, flight paths flown, etc. is attached as a PDF, which forms part of a paper currently being reviewed by BAMS that describes the summer campaign.

The intention of the scale issue is to bring together all of this activity into a single area to allow synergies between the papers to be more evident and to help advertise the data and science generated by the DACCIWA project in this data-poor area to the wider community.