NCAS Unified Model Introduction Part I: Overview of the UM system University of Reading, 16-18 December 2015
The Unified Model The UM is a numerical modelling system, developed by the UK Met Office, and used for operational weather forecasting and climate prediction. It is licensed to the UK academic community for research. There is also the Joint Weather and Climate Research Programme (JWCRP), a strategic partnership between NERC and the Met Office for model development. It is used by forecast centres and climate agencies around the world. 2
Seamless modelling The same core model is used across spatial and temporal scales: Weather to climate timescales Global and regional models High to low resolution (horizontal and vertical) Various model heights It can be used in atmosphere only mode, or coupled to: UM ocean vn6.6.3 or earlier only (e.g. HadGEM2) NEMO ocean and CICE sea-ice via OASIS coupler UKCA chemistry and aerosols JULES land-surface It can also be used to perform idealised studies, e.g: Single Column Model (SCM) Aquaplanet 3
Crown copyright Met Office 4
Global & regional NWP system Parallel suite 36 Global 17km 70 levels (N768L70) EURO 4km 70 levels UKV 1.5km 70 levels [Retired NAE 12km 70 levels] Crown copyright Met Office 5
NWP at the Met Office The UM is just one part of a larger forecast system. An example workflow: Academic users can access this data Crown copyright Met Office 6
Global models Fixed resolutions: (at mid-latitudes) N96 N144 N216 N320 N512 N768 (192 x 145) (288 x 217) (432 x 325) (640 x 481) (1024 x 769) (1536 x 1152) ~135 km ~90 km ~60 km ~40 km ~25 km ~17 km 1.875 x 1.25 1.25 x 0.83 0.83 x 0.56 0.56 x 0.375 0.35 x 0.234 0.234 x 0.16 Common scientific configurations used across scales (weather, seasonal and climate): o o o o o GA = Global Atmosphere (UM) GL = Global Land (JULES) GO = Global Ocean (NEMO) GSI = Global Sea Ice (CICE) GC = Global Coupled (all of the above coupled together) These are ongoing developments with fixed releases. 7
Vertical resolutions Standard resolutions Defined by model levels and height Example: L85 with top at 85 km Crown copyright Met Office 8
NWP v Climate models Run length Global resolution NWP 5 day operational forecast, 15 day ensemble forecast Testing: N320 (40 km) with 15 min ts Operational: N768 (17 km) with 7.5 min ts Climate Months (seasonal) Years, decades, centuries+ Low resolution: N96 (135 km) with 20 min ts High resolution: N512 (25 km) with 15 min ts Calendar Gregorian Seasonal: Gregorian Other: 360 day Dynamics Non-bit reproducible Bit-reproducible Aerosols Climatological concentrations specified. Interactive schemes with emissions specified (not seasonal). Based on information from Dan Copsey 9
HadGEM2(-ES) HadGEM2-ES Full Earth system model Development completed in 2009 Used for IPCC AR5 (CMIP5) N96 1 ocean Physical climate Aerosols and chemistry (UKCA) Ocean biogeochemistry Interactive vegetation (TRIFFID) Other versions available: -A (atmosphere only) -AO (coupled atmosphere-ocean) -CC (carbon-cycle) Earth system minus UKCA Human emissions 10
HadGEM3(-AO) Under continuous development. There are versions with: different code releases different scientific configurations Multiple resolutions: N96 ORCA0.25 N216 ORCA0.25 N512 ORCA0.25 / ORCA12 (experimental) UM atmosphere (GA) OASIS3 coupler NEMO ocean model (GO) JULES land surface (GL) CICE sea ice (GSI) Can run atmosphere-only (Modified from a Met Office diagram.) 11
Other modelling systems MOGREPS: ensemble forecast Based on Parallel Suites GloSea: seasonal prediction Based on HadGEM3 DePreSys: decadal prediction Based on HadGEM3 (formerly HadCM3) 12
Terminology Model version: defines the code base used. Model configuration: defines the science options, eg GA6.0, GO5.0. Modelling system: application with specific configuration (eg HadGEM3-GC2, GloSea5). Parallel suite: version of operational forecast system Job: particular instance defined and run by user through (UMUI) Experiment: grouping of jobs in UMUI Suite: Rose job 13
Major UM developments Old dynamics New dynamics FCM NEMO & CICE ENDGame Rose Shared repositories UM 4.5 UM 5.2 UM 6.1 UM 6.6 UM 7.1 UM 8.5 UM 9.0 UM 10.0 1998 2001 2005 2007 2008 2013 2014 2015 Climate models HadCM3 HadGEM1 HadGEM2 HadGEM3 NWP models PS12 PS19 PS20 PS34 PS35 PS36 Dynamical core Infrastructure Ocean model 14
UM software (pre vn9.0) UMUI Database of user jobs Graphical job editor FCM Code manager Compilation and build PUMA HPC Reconfiguration Prepares initial model state Atmosphere model Dynamical core Physics Diagnostics (STASH) [JULES and/or UKCA] OASIS Coupler Ocean model Input file tools Prepare ancillary data Output file tools Data processing Analysis and visualisation Local / Jasmin 15
UM software (vn10.0 onwards) UMUI Rose Database of user jobs Graphical job editor Cylc / Rose Job submission Workflow manager PUMA FCM Code manager Compilation and build MOSRS HPC Reconfiguration Prepares initial model state Atmosphere model Dynamical core Physics Diagnostics (STASH) [JULES and/or UKCA] OASIS Coupler Ocean model Input file tools Prepare ancillary data Output file tools Data processing Analysis and visualisation Local / Jasmin 16
NCAS supported machines NOC PUMA Code repositories Web server (Trac) User /home space UMUI, Rose/Cylc and FCM MOSRS Repositories: Code (UM 10.x) Rose suites UM submission Lander Rose VM MONSooN Polaris HPC Wales File systems: /home and /work RDF File systems: /home, /projects MASS Jasmin 17
Upcoming UM developments Short-term: Release of GA7 (and GC3) Medium term: N1024 -> N2048 global forecasts UKESM(-Hi /-Lo) Earth system model To include land ice sheets, ocean biogeochemistry, plus carbon and nitrogen cycles Long term: LFRiC replacement for the UM GungHo highly scalable dynamical core 18