NCAS
Unified Model Introduction
Part 1a: Overview of the UM system
University of Reading, 3-5 December 2014
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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Atmospheric
grid length
4km
UKCM
UKV
1.5km
Under Development
Production system
Retired
Euro4
Global
UK4
NAE
12km
Global
24km
HadGEM3-RA
regional
GloSea5
MOGREPS-R
ensemble
UKESM1-Hi
HadGEM3-GC2 HadGEM2 – ES
TIGGE
40km
DePreSys
4
HadGEM1
GloSea4
Earth System
PRECIS
80km
DePreSys
HadCM3
Coupled atmos/ocean
150km
Global atmosphere-only
300km
Regional atmosphere-only
36hrs
48hrs
5 days
15 days
6 months
10 years
30 years
>100 years
Timescale
Modified from a Met Office diagram.
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Global & regional NWP system
Parallel suite 34
Global 17km 70 levels
(N768L70)
EURO 4km 70 levels
UKV 1.5km 70 levels
[Retired NAE 12km 70 levels]
© Crown copyright Met Office
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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
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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.
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Vertical resolutions
Standard resolutions
Defined by model levels and height
Example:
L85 with
top at 85 km
© Crown copyright Met Office
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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 ts
Low resolution:
N96 (135 km) with 20 min ts
Operational:
N768 (17 km) with 7.5 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
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HadGEM2(-ES)
HadGEM2-ES
Physical climate
• 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)
Other versions available:
• -A (atmosphere only)
• -AO (coupled atmosphere-ocean)
• -CC (carbon-cycle) Earth system
minus UKCA
Human emissions
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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)
JULES land surface (GL)
OASIS3
coupler
NEMO ocean model (GO)
CICE sea ice (GSI)
Can run atmosphere-only
(Modified from a Met Office diagram.)
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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
New
dynamics 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
PS34
(PS35)
Climate models
HadCM3
HadGEM1
HadGEM2
HadGEM3
NWP models
PS12
Dynamical core
PS19
Infrastructure
PS20 …
Ocean model
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UM software
UMUI
Database of user jobs
Graphical job editor
Reconfiguration
Prepares initial
model state
PUMA
FCM
Code manager
Compilation and build system
Atmosphere model
Dynamical core
Physics
parameterisations
Diagnostics (STASH)
[JULES and/or UKCA]
Input file tools
Prepare ancillary data
HPC
OASIS
Ocean model
Output file tools
Data processing
Analysis and visualisation
Local / Jasmin
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NCAS supported machines
Code repositories
Web server (Trac)
User /home space
PUMA
UM submission
HPC
Lander
Polaris
MONSooN
File systems:
/home and /work
HPC Wales
File systems:
/home, /projects
and /nerc
MASS
RDF
Local
user ssh to all
Jasmin
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