School of Earth and Environment INSTITUTE FOR CLIMATE AND ATMOSPHERIC SCIENCE The UK Chemistry and Aerosol Project (UKCA) Ken Carslaw

UKCA NCAS–Met Office programme to develop a community coupled aerosol-chemistry-climate model based on the Unified Model Streamlines the aerosol and chemistry code in the UM to create a single “UKCA sub-model” Project partners are the Hadley Centre and the Universities of Cambridge, Leeds (with Oxford and Reading) Running since 2004

UKCA aerosol UKCA aerosol sub-model is a significant advance on previous UM scheme Much wider range of applications (consistent model across climate, air quality, Earth system research) New features: Dynamic aerosol size distribution Full microphysics Internal mixing of particles Better radiative properties, CCN activity, etc. New chemical components (NH 4 +, NO 3 -, SOA, etc) and coupled aerosol-chemistry

UKCA collaboration Leeds: aerosol dynamics, composition, evaluation Inorganic mixed aerosol composition collaboration with Manchester Secondary organic aerosol development as part of the QUEST-QUAAC project Met Office: Tropospheric chemistry, cloud chemistry, radiation coupling, UM sub-model coding Cambridge: Trop and strat chemistry, nudging

UKCA wider collaboration UKCA is a community model that will improve rapidly as it is applied and evaluated in many other projects. Current examples include: The European Integrated Project (EUCAARI) using UKCA/UM as part of the Earth System modeling work package and campaign analysis NERC APPRAISE Aerosol Programme (ADIENT direct effect and ACES organic aerosol consortia Stratospheric aerosol and geoengineering in a NERC Cambridge/Leeds collaboration Met Office CASE projects: Heterogeneous chemistry; Dust and DMS in the Earth System; Arctic aerosol/climate; Ozone indirect effects; Cloud drop number and indirect effect UKCA is the basis for NERC’s new Earth System Model Will be implemented in the ECMWF-IFS in the EU MACC project

One model, many applications The same aerosol/chemistry model is implemented in a CTM, a GCM, an Earth System Model and (from 2010) the ECMWF operational model ECMWF-Integrated Forecasting System (EU MACC project) Air quality prediction

UKCA in the Met Office UKCA Troposphere & Stratosphere & Aerosols Short-term numerical weather prediction & Visibility forecasts JULES Land surface Seamless prediction Seasonal forecasting Decadal prediction Climate projections AR5 - HadGEM2-ES Climate projections Post-AR5 HadGEM2/3-ES AQ forecasts Biogenic emissions AQUM project MACC project Aerosol forcing UKCA-trop UKCA-strat UKCA-whole atm UKCA-MODE UM Slide from O. Boucher, Met Office

Some model applications

Radiative forcing potential of regional SO 2 emissions CCN production from unit SO 2 emission varies by a factor 3 between Asia, US and Europe Asia Europe US SO4CNCCN Manktelow 2008 (NCAS student)

New particle formation New particle formation substantially alters the magnitude of indirect forcing (+-50% regional changes) A neglected process in existing climate models

Asian dust-sulphate interaction Impact of the ACE-Asia “perfect dust storm” on SO 4 aerosol much smaller than previously estimated (few % in most polluted regions) Dust gets saturated with SO 4 Dust loading (  g m -3 ) % sulphate on dust

Opportunities for collaboration Impact of aerosol on Monsoon dynamics Ideal application of UKCA-UM Dust uplift and dynamics Rapidly growing research community in the UK Climate and Earth system applications (nutrients, long term change, etc), uplift micrometeorology, direct forcing, model development Air quality-climate interaction Single model Policy driven research Combined observation and modelling campaign focussed on aerosol and composition