NCAS Unified Model Introduction Part 1a: Overview of the UM system University of Reading, 18-20...
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Transcript of NCAS Unified Model Introduction Part 1a: Overview of the UM system University of Reading, 18-20...
NCAS Unified Model Introduction
Part 1a: Overview of the UM system
University of Reading, 18-20 March 2015
2
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.
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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 and CICE (ocean and 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
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Global & regional NWP system
Global 17km 70 levels(N768L70)
EURO 4km 70 levels
UKV 1.5km 70 levels
[Retired NAE 12km 70 levels]
© Crown copyright Met Office
Parallel suite 35
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NWP at the Met Office
© Crown copyright Met Office
The UM is just one part of a larger forecast system. An example workflow:
Academic users can access this data
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Global models
• Fixed resolutions:
• Common scientific configurations used across scales (weather, seasonal and climate): o GA = Global Atmosphere (UM)o GL = Global Land (JULES)o GO = Global Ocean (NEMO)o GSI = Global Sea Ice (CICE)o GC = Global Coupled (all of the above coupled together)
• These are ongoing developments with fixed releases.
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°
(at mid-latitudes)
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Vertical resolutions
© Crown copyright Met Office
Standard resolutionsDefined by model levels and height
Example: L85 with top at 85 km
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NWP v Climate models
NWP Climate
Run length 5 day operational forecast,15 day ensemble forecast
Months (seasonal)Years, decades, centuries+
Global resolution Testing: N320 (40 km) with 15 min tsOperational: N768 (17 km) with 7.5 min ts
Low resolution: N96 (135 km) with 20 min tsHigh resolution: N512 (25 km) with 15 min ts
Calendar Gregorian Seasonal: GregorianOther: 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
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HadGEM2(-ES)
HadGEM2-ES• Full Earth system model• Development completed in 2009 • Used for IPCC AR5 (CMIP5) • N96 – 1° ocean Aerosols and chemistry (UKCA)
Ocean biogeochemistry
Interactive vegetation (TRIFFID)
Human emissions
Physical climate
Other versions available:• -A (atmosphere only) • -AO (coupled atmosphere-ocean)• -CC (carbon-cycle) Earth system
minus UKCA
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HadGEM3(-AO)
(Modified from a Met Office diagram.)
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)
Can run atmosphere-only
UM atmosphere (GA)
CICE sea ice (GSI)NEMO ocean model (GO)
OASIS3coupler
JULES land surface (GL)
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Other modelling systems
• MOGREPS: ensemble forecast– Based on Parallel Suites
• GloSea: seasonal prediction – Based on HadGEM3 coupled model with NEMO-CICE
• DePreSys: decadal prediction– Based on HadCM3 (due to be upgraded to HadGEM3)
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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
Experiment: grouping of jobs in UMUI
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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 modelsPS12 PS19 PS20 PS34 PS35
Dynamical core Infrastructure Ocean model
…
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Atmosphere modelDynamical corePhysics parameterisationsDiagnostics (STASH)[JULES and/or UKCA]
UM software
UMUIDatabase of user jobsGraphical job editor
FCMCode managerCompilation and build system
ReconfigurationPrepares initial model state
Input file toolsPrepare ancillary data
Output file toolsData processingAnalysis and visualisation
PUMA
HPC
Local / Jasmin
OASIS
Ocean model