Rein Haarsma KNMI (lead) Malcolm Roberts Met Office (co-lead) HighResMIP Rein Haarsma KNMI (lead) Malcolm Roberts Met Office (co-lead) Important weather and climate processes emerge at sub-50km resolution They contribute significantly to both large-scale circulation and local impacts, hence vital for understanding and constraining regional variability How robust are these effects? Is there any convergence with resolution across models? Need coordinated, simplified experimental design to find out http://www.wcrp-climate.org/index.php/modelling-wgcm-mip-catalogue/429-wgcm-hiresmip Global drivers Regional variability Feedbacks to large scale Note: the use of both AMIP-style and coupled integrations – it is not necessary to do both, if that is not possible. An AMIP comparison would lead to significant increased understanding in itself. Coupled models consist of pairs of control (using fixed 1950’s forcing) and experiment with historic and then projection forcings to 2050 Both the aerosol concentrations and the SST and sea-ice forcing datasets and tools will be supplied, as far as is possible – for AMIP-style the historic period will use HadISST, while the future will use the methodology of Mizuta et al from MRI. Input to aerosol concentrations are expected from RFMIP. Experimental protocol: Global models – AMIP-style and coupled Physical climate system only Integrations: 1950-2050 Ensemble size: >=1 (ideally 3) Resolutions: <25km HI and ~60-100km STD Aerosol concentrations specified Local processes Impacts, extremes e.g. Zhao et al, 2009; Haarsma et al, 2013; Demory et al, 2013

Malcolm Roberts, Met Office (coordinator) Pier Luigi Vidale, Univ Malcolm Roberts, Met Office (coordinator) Pier Luigi Vidale, Univ. of Reading (scientific coordinator) PRocess-based climate sIMulation: AdVances in high resolution modelling and European climate Risk Assessment Goal: to deliver novel, advanced and well-evaluated high-resolution global climate models (GCMs), capable of simulating and projecting regional climate with unprecedented fidelity, out to 2050. To deliver: innovative climate science and a new generation of European advanced GCMs. improve understanding of the drivers of variability and change in European climate, including extremes, which continue to be characterised by high uncertainty new climate information that is tailored, actionable and strengthens societal risk management decisions with sector-specific end-users new insights into climate processes using eddy-resolving ocean and explicit convection atmosphere models To run for 4 years from Nov 2015 including 19 partners across Europe, funded by the Horizon 2020 call SC5-1-2014 - Advanced Earth System Models proj.badc.rl.ac.uk/primavera Core integrations in PRIMAVERA will form much of the European contribution to CMIP6 HighResMIP http://www.wcrp-climate.org/index.php/modelling-wgcm-mip-catalogue/429-wgcm-hiresmip Note: the use of both AMIP-style and coupled integrations – it is not necessary to do both, if that is not possible. An AMIP comparison would lead to significant increased understanding in itself. Coupled models consist of pairs of control (using fixed 1950’s forcing) and experiment with historic and then projection forcings to 2050 Both the aerosol concentrations and the SST and sea-ice forcing datasets and tools will be supplied, as far as is possible – for AMIP-style the historic period will use HadISST, while the future will use the methodology of Mizuta et al from MRI. Input to aerosol concentrations are expected from RFMIP.

Modelling groups expressing interest in HighResMIP (at least for Tier 1 simulations) Country Group Model China BCC BCC-CSM2-HR Brazil INPE BESM Chinese Academy of Meteorological Sciences CAMS-CSM Institute of Atmospheric Physics, Chinese Academy of Sciences FGOALS USA NCAR CESM Center for Earth System Science/Tsinghua University CESS/THU Italy Centro Euro-Mediterraneo sui Cambiamenti Climatici CMCC France CNRM-CERFACS CNRM Europe EC-Earth consortium (11 groups) EC-Earth GFDL Russia Institute of Numerical Mathematics INM Japan AORI, University of Tokyo / JAMSTEC / National Institute for Environmental Studies MIROC6-CGCM NICAM Germany Max Planck Institute for Meteorology (MPI-M) MPI-ESM Meteorological Research Institute MRI-AGCM3.xS UK Met Office UKESM /HadGEM3

European HighResMIP resolutions (as part of PRIMAVERA) Example resolutions which will definitely contribute to HighResMIP Concentrate on horizontal resolution – keep vertical resolution the same ECMWF is an NWP partner – present day simulations, extra ensemble members, and including very high resolution atmosphere simulations – we welcome other NWP centres’ submissions

Anticipated outcomes from this meeting Agree to as much of the protocol as possible Suggested way forward for any other aspects Complete email contact list to participate in GMD HighResMIP protocol manuscript (open April – December 2015) PRIMAVERA starts 1 Nov – need protocol in place (and ideally tested) by then.

HighResMIP model configurations (1) Parallel standard and high resolution integrations STD likely to be default CMIP5/CMIP6-DECK resolution (~100km atmosphere resolution) Hence DECK is benchmark for STD, HI is sensitivity test HI being ~25km atmosphere resolution Strongly encourage absolutely minimal differences between STD and HI configurations Vital part of HighResMIP is to look for systematic differences with model resolution across multi-model ensemble If extra tuning is made between different resolutions, it will make it extremely hard to pick apart the causes of differences NOT a beauty contest to have the perfect HI model, we are most interested in the delta between resolutions Similarly vertical resolution should be the same in STD and HI

HighResMIP model configurations (2) Diagnostics list Initial submission to CMIP6 for HighResMIP diagnostic list (having attempted to consult widely on required diagnostics) Considerable number of extra high frequency (1h, 3h, 6h) diagnostics compared to CMIP5 list, to look at extreme processes in particular Balance between scientific interest and manageable data volumes Integration protocol (STD + HI) Physical climate system only, minimal Earth System components Tier 1: simple 1950-2050 forced-atmosphere integrations using SST and sea-ice datasets to be provided Tier 2: coupled simulations 1950-2050 Tier 3: extension of forced integration to 2100 Tier 4: aquaplanet Tier 5: switch-on 4xCO2 Further discussions on more detailed aspects of protocol are ongoing, and will be published in GMD Special Issue later in 2015 Will also be published on HighResMIP wiki, together with helpful scripts for producing forcing datasets Contacts: haarsma@knmi.nl, malcolm.roberts@metoffice.gov.uk Groups should get together for other Tier 3+ simulations (i.e. Those outside PRIMAVERA) to agree between themselves

HighResMIP protocol choices (1) 1950-2050 time period Positives: Longer period than typical 1979-2008 AMIP period (overlap with CMIP6 DECK period will give extra ensemble member at low resolution) Sample different periods of variability from the past, influence of phases of global modes of variability Enables examination of decadal variability of different signs in tropical cyclones, Sahel rainfall etc Idealised climate change signal several decades into future Negatives More expensive Fewer ensemble members possible Methodology for future period will be new, and not so interesting to some, e.g. NWP centres signal to noise may be small

HighResMIP protocol choices (2) All models use the same aerosol concentrations timeseries (provided by e.g. RFMIP) Positives: Multi-model comparison concentrates on physical resolution impact Cleaner comparison than e.g. CMIP5 Influences on e.g. decadal variability the same Negatives Complicated with different aerosol schemes in different models Providing aerosol datasets reliant on other projects, e.g. RFMIP Models may need retuning from their standard aerosol climatology (though this may have been tuned at low resolution anyway)

HighResMIP protocol choices (3) No retuning of model between low and high resolution Positives: Enables assessment of impact of horizontal resolution alone Hence essential for the basic outcome of HighResMIP High resolution expensive to tune anyway Negatives Higher resolution may not be ideal configuration May be issues with TOA radiation Document all changes made between resolutions If insist, then show sensitivity studies so can understand what is resolution and what is tuning

HighResMIP protocol choices (4) Diagnostics and data output at high frequency (more at 6hr, 3hr and 1hr) as well as column-integrated Positives: Significant new analysis becomes possible, including extreme processes and events (polar lows, Medicanes, intense precipitation, atmospheric rivers etc) Encourages central analysis platform and sharing common analysis tools (rather than downloading huge volumes of data to local space) Makes best use of HPC usage (run once, analyse many) Negatives Significant storage requirements (~400GB per model year at 25km resolution for priority 1 data) More difficult to share data – no longer possible to store all diagnostics on CMIP5 data node (use of shared JASMIN platform will help this for coordinated analysis

SST and sea-ice protocol for forced-atmosphere (current plan) 1950 - present day Based on HadISST HadISST machinery can produce daily, 1/4˚ fields Use fixed SST and sea-ice (rather than slab-ocean where model comparison will be harder) Present day – 2050 (2100) SST Find period in past with similar phase of major modes of variability Stitch this to the present day Use trend in HadISST into the future (or use CMIP5 models for future trend) Sea-ice use Mizuta et al methodology to scale present-day sea-ice shape into future based on global SST change KNMI methodology

Coupled model protocol (current plan) 1950 ocean initial condition EN4 from observed profiles and analyses in 1950 Present day ocean (more observations but longer spin-up) Coupled spin-up strategy Start from 1950 state, run with 1950’s atmosphere forcing until TOA at acceptable level (both high and low resolution ocean) - ~decades Start from present day, run with 1950’s atmosphere until TOA acceptable (both high and low resolution ocean) - ~decades Use lower resolution model for spin-up and interpolate final ocean state to higher resolution – either ~decades or use CMIP6 DECK (will lock-in biases from low resolution)

Q&A