In situ constraints on the vertical distribution of global aerosol

Duncan Watson-Parris*, Nick Schutgens, Carly Reddington, Kirsty J. Pringle, Dantong Liu, James D. Allan, Hugh Coe, Ken S. Carslaw, Philip Stier

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


Despite ongoing efforts, the vertical distribution of aerosols globally is poorly understood. This in turn leads to large uncertainties in the contributions of the direct and indirect aerosol forcing on climate. Using the Global Aerosol Synthesis and Science Project (GASSP) database - the largest synthesised collection of in situ aircraft measurements currently available, with more than 1000 flights from 37 campaigns from around the world - we investigate the vertical structure of submicron aerosols across a wide range of regions and environments. The application of this unique dataset to assess the vertical distributions of number size distribution and cloud condensation nuclei (CCN) in the global aerosol-climate model ECHAM-HAM reveals that the model underestimates accumulation-mode particles in the upper troposphere, especially in remote regions. The processes underlying this discrepancy are explored using different aerosol microphysical schemes and a process sensitivity analysis. These show that the biases are predominantly related to aerosol ageing and removal rather than emissions.

Original languageEnglish
Pages (from-to)11765-11790
Number of pages26
JournalAtmospheric Chemistry and Physics
Issue number18
Publication statusPublished - 23 Sept 2019


Duncan Watson-Parris and Philip Stier acknowledge funding from Natural Environment Research Council projects NE/J022624/1 (GASSP), NE/L01355X/1 (CLARIFY), NE/M017206/1 (IMPALA) and NE/P013406/1 (A-CURE) and from the Science and Technology Facilities Council project ST/P003206/1 (EVADE). Philip Stier also acknowledges funding from the European Research Council project RECAP under the European Union’s Horizon 2020 research and innovation programme with grant agreement 724602 and the European Union’s Seventh Framework Programme (FP7/2007-2013) project BACCHUS under grant agreement 603445. Ken S. Carslaw acknowledges funding from the Natural Environment Research Council projects NE/J022624/1 (GASSP), NE/L01355X/1 (CLARIFY) and NE/P013406/1 (A-CURE). The ECHAM-HAMMOZ model is developed by a consortium composed of ETH Zurich, Max Planck Institut für Meteorologie, Forschungszentrum Jülich, University of Oxford, the Finnish Meteorological Institute and the Leibniz Institute for Tropospheric Research, and managed by the Center for Climate Systems Modeling (C2SM) at ETH Zurich. The ECHAM-HAM simulations were performed using the ARCHER UK National Supercomputing Service. FAAM airborne data were obtained using the BAe-146 Atmospheric Research Aircraft, which was operated by Airtask and jointly funded by the UK Natural Environment Research Council (NERC) and the Met Office. We are grateful to the many PIs who contributed their data to GASSP: Thomas Choularton (ACCACIA, COPE); James Hudson (ACE1, INDOEX); Anthony D. Clarke (ACE1, ACEASIA/ACE-Asia, ARCTAS, INDOEX, INTEX-A, MIRAGE, PASE, PEM-Tropics A+B, VOCALS-REx); Hugh Coe (AMMA, AEGEAN-GAME, BORTAS, EUCAARI-LONGREX, OP3, RONOCO, VOCALS-REx); Jamie Trembath (APPRAISE, EM25, EUCAARI-LONGREX, RONOCO, TROMPEX, VOCALS-REx); Athanasios Nenes (ARCPAC, ARCTAS, CALNEX, DC3, DISCOVER-AQ, SEAC4RS, TEXAQS-GoMACCS 2006); Ann Middlebrook (ARCPAC, CALNEX, TEXAQS-GoMACCS 2006); Roya Bahreini (ARCPAC, CALNEX, TEXAQS-GoMACCS 2006); Jose-Luis Jimenez (ARCTAS, DC3, INTEX-B, MIRAGE, SEAC4RS); Bruce Anderson (DISCOVER-AQ, INTEX-A); Jen-nifer M. Comstock (GoAmazon); Fan Mei (GoAmazon); Rodney Weber (INTEX-A); Greg Roberts (INTEX-B, MIRAGE); Steven Howell (PASE, VOCALS-REx); Daniel J. Jacob (PEM-Tropics A); Geraldine M. Gardner (PEM-Tropics A); Martin G. Schultz (PEM-Tropics A); Robert Talbot (PEM-Tropics A, PEM West A); and Jefferson Snider (VOCALS-REx). Financial support. This research has been supported by the Nat- ural Environment Research Council (grant nos. NE/J022624/1 (GASSP), NE/L01355X/1 (CLARIFY), NE/M017206/1 (IMPALA), and NE/P013406/1 (A-CURE)), the Science and Technology Facilities Council (grant no. ST/P003206/1 (EVADE)), the European Research Council (grant no. RECAP (724602)) and the European Commission (grant no. BACCHUS (603445)).

FundersFunder number
Environment Research Council
Horizon 2020 Framework Programme724602, 603445
Natural Environment Research CouncilNE/P013406/1, NE/J022624/1, NE/M017206/1, NE/L01355X/1
Science and Technology Facilities CouncilST/P003206/1
European Commission
European Research Council
Met Office
Seventh Framework Programme


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