© Crown copyright 2007 Page 1 The Met Office climate model HadSM3 and climateprediction.net Michael Saunby 25 January 2007
Jan 11, 2016
© Crown copyright 2007 Page 1
The Met Office climate model HadSM3 and climateprediction.net
Michael Saunby 25 January 2007
© Crown copyright 2007 Page 2
The Hadley Centre for Climate Change
Branch of the Met Office - UK national meteorological service
Opened by Prime Minister Mrs Thatcher in 1990
Funded by DEFRA and MOD to research climate change
Moved from Bracknell to Exeter in 2004
120 staff
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climateprediction.net
University of Oxford, Rutherford Appleton Laboratory, The Open University
Funded by NERC, DTI, EU and BBC
Goals Improve public understanding of the nature of
uncertainty in climate prediction.Harness the power of idle home and business PCs
to help forecast the climate of the 21st century.
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The Unified Model - origins
By the end of the 1980s the Met Office had developed separate numerical prediction models to sustain climate research and operational forecast capabilities.
Each model had its own control, file and output structure, as well as separate scientific formulations, with separate teams responsible for development.
UM reduces the effort required to implement models
on new hardware.
CDC Cyber 205, Cray YMP-8, C90, T3E, NEC SX6, SX8
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Unified Model - today
Met Office using NEC SX6 and SX8
MPI introduced at 4.1 (T3E)
Ported Unified Model (PUM). Cray, IBM, Clusters, even single CPU
Current release UM 6.3. HadGEM1 UM4.7 HadCM3 etc. widely used, esp. ensembles
C for I/O. Tcl/Tk for UI
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Met Office supercomputing
3 clusters –•15 x SX-6•19 x SX-6•21 x SX-8
128GFlops64GFlopsPeak/node
64GByte32GByteMemory
88CPU/node
SX-8SX-6
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Development environment
Linux workstations (32 bit)
Linux front-end and fileservers. (64 bit Intel)
NEC SX6/SX8. Super UX. Vector processors
Code management with FCM (Open Source) – uses Subversion and lots of Perl
Automated change from fixed to free format
Last release ~750k lines Fortran~250k lines changed!
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The climate system
OCEAN
PrecipitationSea-ice
LAND
Ice- sheetssnow
Biomass
Clouds
Solarradiation
Terrestrialradiation
Greenhouse gases and aerosol
ATMOSPHERE
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Climate model development
N144HI-GEM
Reading CGAM
HadCEMatmosphere, ocean
HadCM3 atmosphere,
ocean, sulphur
Regional model
N96 earth systematm osphere, ocean,
sulphur, chem .,carbon cycle, blackcarb
N48 earth systematm osphere, ocean,
sulphur, chem ., black carbcarbon cyc le (TRIFF ID, OCC),
N48 L 38 b aselin eatm o sp h ere, o cean ,
su lp h u r, ch em istry (so m e ru n s)co n tro l - p resen t/p re-in d u strial
Regional model
ENSEMBLESQ UMP
HadCM3
N96 L19HadA M3H
HadCM3
HadGEM1
HadGEM2
Newdeep
convection
DecadalSeasonal (G losea)Climate variability
FAMO US G EMlow resolution
newcloud
schem e
FLU MEUM structureancillary files
STASH / diagnostics
O PAOcean
HadCM 3 & FAMO USvarious resolution
carbon cyclechemistry
N96 L50atmosphere, ocean,
sulphurRunning on NEC
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Model is about 1 million lines of Fortran (40MB src) Proprietary, licenced by UK MetOffice
distribute executable/binary form only Resolution used: 2.75x3.75 degrees (73 lat x 96 long) Typically run on a supercomputer (i.e. Cray T3E) or 8-
node Linux cluster (minimum) Ported to a single-processor, 32-bit Linux box Original: Windows only, now also Mac OS X, Linux Intel Fortran Win & Linux, IBM XLF for Mac, soon Intel
Mac Many validation runs made on single-proc/32-bit to
compare to supercomputer 64-bit Current coupled model takes ~6 months to run on a
P4/2GHz PC 24/7!
CPDN volunteer computing challenges...
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A specialized form of “distributed computing”
Uses BOINC - Berkeley Open Infrastructure for Network Computing
Was around before '99 but took off with SETI@home
SETI@home peak cap with 500K users about 1 PF = 1000 TF for comparison Earth Sim in Kyoto = 35TF max
climateprediction.net (CPDN) running at about 60 TF (60K concurrent users each 1GF machine average, i.e. PIV 2GHz conservatively rated)
Offers high CPU power at low cost
Volunteer Computing
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The experiments
Expt 2: Fully coupled model. (HadCM3) Distribute pre-packaged simulations of 1950-2050. Downweight or eliminate runs which compare badly with observations. Re-distribute the surviving versions to simulate 2000-2050. Estimate uncertainty from collated results and map the response manifold.
Expt 1: Unified Model with simple, thermodynamic ocean. (HadSM3) Aim: To identify parameter combinations which have little effect on the
mean climate but a large effect on climate sensitivity.
15 yr spin-up 15 yr, base case CO2
15 yr, 2 x CO2
Derived fluxes
Diagnostics from final 8 yrs.
Calibration
Control
Double CO2
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climateprediction.net users worldwide
>300,000 users total : ~60,000 active (currently running)>19 million model-years simulated (as of January 2007)
~200,000 completed simulations
The world's largest climate modelling supercomputer!(NB: a black dot is one or more computers running climateprediction.net)
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climateprediction.net Screensavers
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Example BBC experiment run
Climate sensitivities from climateprediction.net
Stainforth et al, Nature, 27 Jan ‘05
The frequency distribution of simulated climate sensitivity using all (2,578) model versions (black), all model versions except those with perturbations to the cloud-to-rain conversion threshold (red), and all model versions except those with perturbations to the entrainment coefficient (blue).
Sensitivity is the equilibrium response of the global mean temperature of doubling atmospheric levels of carbon dioxide.
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Frequency Distribution of Simulations
From Stainforth et al, Nature, 27 Jan ‘05
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D. A. Stainforth, T. Aina, C. Christensen, M. Collins, N. Faull, D. J. Frame, J. A. Kettleborough, S. Knight, A. Martin, J. M. Murphy, C. Piani, D. Sexton, L. A. Smith, R. A. Spicer, A. J. Thorpe & M. R. Allen, Uncertainty in predictions of the climate response to rising levels of greenhouse gases, Nature, 433, pp.403-406, 27/01/2005
D. J. Frame, B. B. B. Booth, J. A. Kettleborough, D. A. Stainforth, J. M. Gregory, M. Collins, and M. R. Allen, Constraining climate forecasts: The role of prior assumptions, Geophysical Review Letters, 32, L09702, May 2005.
C. Piani, D. J. Frame, D. A. Stainforth, and M. R. Allen, Constraints on climate change from a multi-thousand member ensemble of simulations, Geophysical Review Letters, 32, L23825, December 2005.
G.C. Hegerl, T.J. Crowley, W.T. Hyde and D. J. Frame, Climate sensitivity constrained by temperature reconstructions over the past seven centuries, Nature, 440, p1029-1032, April 2006.
Allen, M., N. Andronova, B. Booth, S. Dessai, D. Frame, C. Forest, J. Gregory, G. Hegerl, R. Knutti, C. Piani, D. Sexton, D. Stainforth, 2006, Observational constraints on climate sensitivity, in Avoiding Dangerous Climate Change, (Eds.) J.S. Schellnhuber, W. Cramer, N. Nakicenovic, T.M.L. Wigley, G. Yohe., Cambridge Univ. Press.PDF of complete book (17 MB), see chapter 29
Knutti, R., G.A. Meehl, M.R. Allen and D. A. Stainforth, Constraining climate sensitivity from the seasonal cycle in surface temperature, Journal of Climate, in press
Designing a Runtime System for Volunteer Computing, David P. Anderson, Carl Christensen and Bruce Allen, To appear in Supercomputing ’06 (the International Conference for High Performance Computing, Networking, Storage and Analysis), Tampa, Florida, USA, November 2006.
N. Massey, T. Aina, M. Allen, C. Christensen, D. Frame, D. Goodman, J. Kettleborough, A. Martin, S. Pascoe and D. Stainforth, Data access and analysis with distributed federated data servers in climateprediction.net , Advances in Geosciences, 8, p49-56, 2006.
Carl Christensen, Tolu Aina, David Stainforth, The Challenge of Volunteer Computing With Lengthy Climate Modelling Simulations, Proceedings of the 1st IEEE Conference on e-Science and Grid Computing, Melbourne, Australia, 5-8 Dec 2005
David Stainforth, Andrew Martin, Andrew Simpson, Carl Christensen, Jamie Kettleborough, Tolu Aina, and Myles Allen, Security Principles for Public-Resource Modeling Research, Proceedings of the 13th IEEE Conference on Enabling Grid Technologies (ENTGRID), Modena, Italy, June 2004
climateprediction.net recent publications
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More information
http://www.bbc.co.uk/sn/climateexperiment/
http://www.climateprediction.net/
http://www.metoffice.gov.uk/research/hadleycentre/
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Thanks to
Carl ChristensenMatt CollinsGareth JonesJamie KettleboroughPaul Selwood