Local air pollution from oil rig emissions observed during theairborne DACCIWA campaign

Abstract. In the framework of the European DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) project, the airborne study APSOWA (Atmospheric Pollution from Shipping and Oil platforms of West Africa) was conducted in July 2016 to study oil rig emissions off the Gulf of Guinea. Two flights in the marine boundary layer were focused on the floating production storage and offloading (FPSO) vessel operating off the coast of Ghana. Those flights present simultaneous sudden increases of NO 2 and aerosols concentrations. Unlike what can be found in flaring emission inventories, no increase in SO 2 was detected and an increase in CO is observed only during one of the two flights. Using FLEXPART simulations in forward trajectory mode, our study reproduced the timing of the aircraft NO 2 enhancements. We used a regional NO 2 satellite flaring inventory in the simulations, which showed an overall good estimate of flaring emission. Several sensitivity tests on the flux and the injection height were also performed to better reproduce the measurements.