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UK plans for CMIP6

Colin Jones, NCAS and UKESM core group
Jeremy Walton, Met Office Hadley Centre and UKESM core group

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An important application of UKESM models will be the next round of the World Climate Research Program's Coupled Model Intercomparison Project (CMIP6). CMIP6 aims to improve our understanding of, and ability to simulate, key climate phenomena and future climate change using a coordinated multi-model approach. In CMIP6, UKESM1 and other climate models from around the world will be integrated using a common set of experiment protocols to address a range of key science questions. Comparison across models will help assess their performance and understand common model weaknesses. A multi-model ensemble will also help quantify and constrain the spread amongst future projections. Beginning in late 2016, CMIP6 is scheduled to run actively until the end of 2020.

The organisation of CMIP6 is more distributed than was the case in previous rounds. It contains twenty individual Model Intercomparison Projects (MIPs), each focused on a specific area of Earth system science. In addition, there is a set of fundamental (or DECK) experiments which will be run for each model in order to characterize its performance, and provide a reference point for the various MIP experiments.

Figure 1

Figure 1. Groups coordinating the UK contribution to CMIP6

The UK contribution to CMIP6 will come from the Met Office, NERC centres and UK universities and is being coordinated through a number of thematic groups (see figure) currently working on tasks such as:

  • ensuring model components meet the technical requirements for CMIP6

  • providing technical support for model runs, data conversion and delivery

  • sharing good practice (including experiment setup) across MIPs and coordinating MIP numerical experiments.

Four model versions will be available for UK-CMIP6: two resolutions of UKESM1, and two of the GC3 configuration of the HadGEM3 physical climate model (HadGEM3-GC3 is the coupled physical model core of UKESM1). DECK runs will be performed for each model version; for example, the low-resolution version of UKESM1 will be started by the UKESM core group on the Met Office HPC before the end of 2016. Each MIP has already selected a model version for use in its experiments; for example, the low-resolution version of UKESM1 will initially be used by AerChemMIP, C4MIP, GEOMIP, ISMIP, LUMIP, OMIP, ScenarioMIP and VolMIP. See the World Climate Research Programme website for more details on CMIP6 and the underlying MIPs that constitute CMIP6.

As noted above, an important part of the preparation for CMIP6 is looking at the post-processing of model output. This includes quality checking of all results, and data transformation prior to submission of the output to the Earth System Grid Federation (ESGF), the data repository for all CMIP6 output. Climate scientists will subsequently access the CMIP6 multi-model archive through the ESGF to use in their analyses. Post-processing will be performed for some of the MIPs by the Implementation Team (see above); in addition, this team will make the entire post-processing software available for other users on the JASMIN platform and Met Office internal machines.

A UK-CMIP6 workshop was held at the Met Office in June 2015 which was attended by ~80 scientists from the Met Office, NERC centres and universities. A second workshop is planned for May 18-19 2016 in the same location to firm up simulation and post-processing plans in advance of CMIP6 simulation starting towards the end of 2016. More detailed information about these workshops and UK preparations for CMIP6 is available on the Met Office website.