Print Email Facebook Twitter Aerosol first indirect effect of African smoke at the cloud base of marine cumulus clouds over Ascension Island, southern Atlantic Ocean Title Aerosol first indirect effect of African smoke at the cloud base of marine cumulus clouds over Ascension Island, southern Atlantic Ocean Author De Graaf, Martin (Royal Netherlands Meteorological Institute (KNMI)) Sarna, K. (TU Delft Atmospheric Remote Sensing) Brown, Jessica (Wageningen University & Research) Tenner, Elma V. (Student TU Delft) Schenkels, Manon (Universiteit Utrecht) Donovan, D.P. (Royal Netherlands Meteorological Institute (KNMI)) Date 2023 Abstract The interactions between aerosols and clouds are among the least understood climatic processes and were studied over Ascension Island. A ground-based UV polarization lidar was deployed on Ascension Island, which is located in the stratocumulus-to-cumulus transition zone of the southeastern Atlantic Ocean, to infer cloud droplet sizes and droplet number density near the cloud base of marine boundary layer cumulus clouds. The aerosol–cloud interaction (ACI) due to the presence of smoke from the African continent was determined during the monsoonal dry season. In September 2016, a cloud droplet number density ACIN of 0.3 ± 0.21 and a cloud effective radius ACIr of 0.18 ± 0.06 were found, due to the presence of smoke in and under the clouds. Smaller droplets near the cloud base makes them more susceptible to evaporation, and smoke in the marine boundary layer over the southeastern Atlantic Ocean will likely accelerate the stratocumulus-to-cumulus transition. The lidar retrievals were tested against more traditional radar–radiometer measurements and shown to be robust and at least as accurate as the lidar–radiometer measurements. The lidar estimates of the cloud effective radius are consistent with previous studies of cloud base droplet sizes. The lidar has the large advantage of retrieving both cloud and aerosol properties using a single instrument. To reference this document use: http://resolver.tudelft.nl/uuid:6a6ee478-6ad7-4715-8628-77717a6244ed DOI https://doi.org/10.5194/acp-23-5373-2023 ISSN 1680-7324 Source Atmospheric Chemistry and Physics (online), 23 (9), 5373–5391 Part of collection Institutional Repository Document type journal article Rights © 2023 Martin De Graaf, K. Sarna, Jessica Brown, Elma V. Tenner, Manon Schenkels, D.P. Donovan Files PDF acp_23_5373_2023.pdf 5.83 MB Close viewer /islandora/object/uuid:6a6ee478-6ad7-4715-8628-77717a6244ed/datastream/OBJ/view