UKESM1 developments and plans for CMIP6

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1 UKESM1 developments and plans for CMIP6 Alistair Sellar UKESM science manager

2 Outline Current status of UKESM core group UKESM1 development status and timeline UKESM1 plans for CMIP6

3 UKESM core group: status & funding UKESM core group presently 18 scientists: 8 MOHC and 10 NERC (NCAS(6), NOC(1), CEH(1), BAS(1), PML(1)) UKESM NERC-LTSM proposal submitted Nov 2 nd requesting ~20 FTE/year for 5 years (~May 2016 start). Involves: NCAS, NCEO, CEH, BAS, NOC, CEH, CPOM, BGS If funded the NERC contribution to the core group will increase to 13, with 3 extra members from NCEO(+2) and CEH(+1). The remaining 7 FTE/yr will fund centre-specific activities on UKESM1 evaluation and (UKESM2) component model development

4 HadGEM3 development and UKESM1 UKESM1 is built on the HadGEM3-GC3 physical model A key development in GC3 is the UKCA-GLOMAP aerosol scheme using full aerosol complexity and a highly simplified version of UKCA trace gas chemistry Science performance of the scheme is acceptable. Cost remains an issue. A prototype GC3 is now available, on which we are building the next UKESM prototype version (0.4) This process has been delayed due to GC3 delays.

5 UKESM1: ESM components Chemistry: UKCA stratospheric-tropospheric chemistry including trop. isoprene chemistry (Morgenstern 2009, O Connor 2014) Aerosols: UKCA-GLOMAP-mode, 2-moment, 7-mode, strat-trop aerosol scheme (Mann 2014) Talks by : Colin Johnson and Jane Mulcahy Ocean BGC: MEDUSA2 intermediate complexity plankton ecosystem model (including prognostic DIC, alkalinity, dissolved O 2, detritus carbon with variable C:N) (Yool 2013) Talk by : Julien Palmieri Terrestrial carbon cycle: TRIFFID vegetation dynamics (9 PFTs), prognostic soil carbon, simple N-limitation scheme (Wiltshire, in prep), diagnostic wildfire, improved diagnostic permafrost extent and wetland CH 4 emission Talk by: Anna Harper Ice sheets: BISICLES land ice model over Antarctica and Greenland (Cornforth 2013) Talk by Jonathan Gregory/Robin Smith

6 UKESM1: key ES couplings Atmos-ocean coupling: CO 2, DMS, Iron Atmos-land coupling: CO 2 N (deposition only, emissions prescribed) Interactive isoprene and monoterpene emissions from plants coupled to secondary organic aerosols Chemistry-aerosol couplings: sulfur chemistry aerosol, AOD photolysis, surface area trop. + strat. heterogeneous chemistry Ice sheets/shelves: snow accumulation ice sheet model, ice shelf basal melt (mass loss) ocean freshwater and geometry

7 GLOMAP-mode evaluation Aerosol Optical Depth (550 nm) Evaluation vs Aeronet (440nm) GA6 - Annual proto-ga7- Annual MODIS MISR Jane Mulcahy

8 Planned development versions UKESM0.4: HadGEM3-GC3 + major ESM capabilities UKCA: StratTrop chem, GLOMAP-mode with modal dust JULES-C: + nitrogen cycle, BVOC emissions, 9 PFTs, dynamic vegetation (TRIFFID), diagnostics fires MEDUSA ocean biogeochemistry: CO 2 & DMS coupling to UKCA Aiming for completion Jan 2016, building now. UKESM0.5: Last window for planned science changes Nitrate aerosol (likely now to come post-ukesm1 release), remaining couplings, other (minor) sci/tech developments Aiming for completion March 2016, to allow 6-8 months for tuning / reactive development. UKESM1.0: Ready for CMIP6 production Autumn 2016 UKESM1.0-IS: BISICLES ice sheet model included early 2017

9 Low-resolution UKESM1-lr Talk by Till Kuhlbrodt The resolution for UKESM1-lr has been selected as: Atmosphere: N96 (~130km) Ocean: 1 N48 atmosphere was investigated but science performance was not acceptable UKESM1-lr (full complexity: UKCA chemistry, GLOMAP aerosol, MEDUSA ocean BGC) runs at ~2-2 1 / 2 simulatios years/day. With simplified UKCA trace gas chemistry this increases to ~5+ years/day. Possible development of a UKESM1-lr-fast once UKESM1-lr is released. Fast will come from; e.g. longer dynamical and radiation time steps, reduced call frequency of UKCA and MEDUSA, simplified processes (e.g. grouped tracer advection), improved numerics and code optimization. A number of these have already been worked on now. UKESM1-LR-Fast science performance will be judged against UKESM1-lr Aim to achieve years/day. Will not start until UKESM1-lr is complete.

10 Effective radiative forcing (ERF) To have an acceptable historical simulation UKESM1 external forcings (e.g. GHGs, aerosols, land use change etc) need a reasonable balance. HadGEM2-ES had no historical warming until very late C20 th, due to strong negative aerosol and land use forcing balancing GHG warming. UKESM1 (and HadGEM3-GC3) has the potential for large changes in forcing due to increased complexity in land use change, aerosols and aerosol-cloud interactions (see next slide). As part of UKESM1 development we will estimate key ERFs using AMIP simulations with individual forcing agents set to pre-industrial values: Total (historical)anthropogenic ERF Aerosol ERF Land use ERF We will not look at climate sensitivity or future climate change responses

11 Potential for greatly increased 2nd indirect effect Ian Boutle

12 UKESM1-hybrid Talk by Marc Stringer Full complexity UKESM1 too expensive for CMIP6 at N216/ORCA0.25. Hybrid resolution UKESM is in development: GC3 physical model at N216/ORCA0.25, UKCA-GLOMAP and MEDUSA tracer advection interactively coupled to GC3 (UM/NEMO) but run at a reduced resolution Reduced resolution UM/UKCA-GLOMAP approach Two versions of UM atmosphere Senior N216: high-resolution UM only, coupled to ocean, sea-ice Junior N96: low-resolution UM and UKCA-GLOMAP Senior and Junior UMs coupled by exchanging 3D fields Senior sends aggregated physical atmospheric state to Junior every time step, Junior runs UKCA using this Senior-locked climate and sends trace gas and aerosols back to Senior every hour for use in radiation and clouds Separation of versions allows for better scaling (separate UM executables) In principle applicable to any (supported) resolution combination Potential increase in throughput of ~300% for UKESM1-hybrid versus UKESM1 at N216 Degraded resolution advection of marine BGC tracers under development for NEMO (in Paris) for early 2016 & use in CMIP6 (MEDUSA in UKESM1)

13 UKESM1-hybrid approach HPC cost and throughput Potential increased throughput of UM/UKCA-GLOMAP From ~4.5 x longer than UM to ~1.6 x UM at N216 Degraded resolution advection of marine BGC tracers also under development for NEMO (in IPSL/Paris) for early 2016 & use in CMIP6 (MEDUSA in UKESM1) Marc Stringer & Richard Hill

14 Planned UK CMIP6 timeline (does not include non UKESM core group/mohc led MIPs, e.g. PMIP) Simulations shared between MOHC HPC and ARCHER ~Oct 2016 to early 2020 C4MIP, OMIP, AerchemMIP, LUMIP: UKESM1-LR CFMIP, FAFMIP, RFMIP, DAMIP, LS3MIP: HadGEM3-GC3 N96 HighResMIP, DCPP: HadGEM3-GC3 N216 CMIP6 Historical UKESM1-LR HadGEM3-GC3 N216/N96 Repeat key C4MIP, AerchemMIP, LUMIP, ISMIP6 with UKESM1-hybrid ISMIP6 UKESM1-IS CMIP-DECK UKESM1-LR HadGEM3-GC3 N216/N96 Oct Repeat key ScenarioMIP UKESM1-hybrid ScenarioMIP UKESM1-LR CMIP-DECK UKESM1-hybrid CMIP6 Historical UKESM1-hybrid Part of CMIP-DECK and historical runs using UKESM1-HR Likely not full period runs hence not submitted to ESGF 2020