2019/11/07 HYGEOS contributes to upgraded aerosol scheme of the ECMWF IFS

This paper is a welcome update of the previous 2009 reference paper. It documents exhaustively the aerosol source and sink processes as implemented in the operational cycle 45R1 of the IFS, and provides a short evaluation as compared to an earlier version of the IFS that was used for the CAMS interim Reanalysis. The improvement in the skill of the forecasts of Aerosol Optical Depth (AOD) and PM is important. The major upgrades of cycle 45R1 as compared to cycle 43R3 consists in a new sea-salt aerosol emission scheme and an online aerosol dry deposition scheme that estimates deposition velocity as a function of particle size, friction velocity and land category.