page 1© crown copyright 2007 the met office climate model hadsm3 and climateprediction.net michael...

© Crown copyright 2007

The Met Office climate model HadSM3 and climateprediction.net

Michael Saunby 25 January 2007


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


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.


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


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


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


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!


The climate system

OCEAN

PrecipitationSea-ice

LAND

Ice- sheetssnow

Biomass

Clouds

Solarradiation

Terrestrialradiation

Greenhouse gases and aerosol

ATMOSPHERE


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


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...


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


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


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)


climateprediction.net Screensavers


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.


Frequency Distribution of Simulations

From Stainforth et al, Nature, 27 Jan ‘05


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


More information

http://www.bbc.co.uk/sn/climateexperiment/

http://www.climateprediction.net/

http://www.metoffice.gov.uk/research/hadleycentre/


Thanks to

Carl ChristensenMatt CollinsGareth JonesJamie KettleboroughPaul Selwood

page 1© crown copyright 2007 the met office climate model hadsm3 and climateprediction.net michael...

Documents

climate response

journal of climate

climate sensitivities

david stainforth

constraining climate

dangerous climate change

myles allen

bruce allen