The representation of clouds, aerosols and cloud-aerosol-radiation impacts remain some of the largest uncertainties in climate change, limiting our ability to accurately reconstruct and predict future climate. The south-east Atlantic is a region where high atmospheric aerosol loadings and semi-permanent stratocumulus clouds are co-located, providing a natural laboratory for studying the full range of aerosol-radiation and aerosol-cloud interactions and their perturbations of the Earth’s radiation budget. While satellite measurements have provided some useful insights into aerosol-radiation and aerosol cloud interactions over the region, these observations do not have the spatial and temporal resolution, nor the required level of precision to allow for a process level assessment. Detailed measurements from high spatial and temporal resolution airborne atmospheric measurements in the region are very sparse, limiting their use in assessing the performance of aerosol modelling in numerical weather prediction and climate models. CLARIFY-2017 was a major consortium programme consisting of 5 principal UK universities with project partners from the UK Met Office and European and USA-based universities and research centres involved in the complementary ORACLES, LASIC and AEROCLO-sA projects. The aims of CLARIFY-2017 were four-fold; 1) to improve the representation and reduce uncertainty in model estimates of the direct, semi-direct and indirect radiative effect of absorbing biomass burning aerosols; 2) improve our knowledge and representation of the processes determining stratocumulus cloud microphysical and radiative properties; 3) challenge, validate and improve satellite retrievals of cloud and aerosol properties and their radiative impacts; 4) improve numerical models of cloud and aerosol and their impacts on radiation, weather and climate. This paper describes the modelling and measurement strategies central to the CLARIFY-2017 deployment of the FAAM BAe146 instrumented aircraft campaign, summarises the flight objectives and flight patterns, and highlights some key results from our initial analyses.
Acknowledgements. We would like to thank Sarah Taylor and Ed Gryspeerdt for putting together Fig. 1 at the proposal stage. Tony Radakin and the Joint Forces Command are thanked for their support for the CLARIFY project. Andy Pittock of the RAF was instrumental in making this project a success through the support given to us during the detachment; the can-do attitude of the RAF was very much appreciated throughout the duration of the deployment. Jonny Hobson and the staff of the Obsidian Hotel are thanked for their hospitality, and Jonny deserves particular thanks for providing us with interesting tours of the flora and fauna of the island. The staff of Air Task, Avalon Engineering, and FAAM are thanked for their thoroughly professional service, before, during, and after the deployment. The support from Met Office staff at Ascension Island, Amy Raynor (Senior Met Officer), Emma Sillitoe, John Hill, and Katie Tobin, was also appreciated. This work was mainly supported by the NERC Large Grant NE/L013584/1. Jim M. Haywood, Anthony C. Jones, Florent Malavelle, Michael I. Cotterell, and Fanny Peers were also supported by the Research Council of Norway via the projects AC/BC (240372) and NetBC (244141). Philip Stier would additionally like to acknowledge funding from the European Research Council (ERC) project (RECAP) under the European Union’s Horizon 2020 Research and Innovation programme (grant agreement 724602) and the Natural Environment Research Council project NE/P013406/1 (A-CURE).
Financial support. This research has been supported by the Nat-
© 2021 Georg Thieme Verlag. All rights reserved.