Production of global climate change scenarios in RT1 and RT2A

Jean-Francois Royer (RT2A)

James Murphy (RT1)

Aims of RT1 and RT2A

• Produce ensembles of global climate simulations with earth system models, and provide model results needed in other RT

• Use two different approaches to sample climate uncertainty:– Multi-model (RT2A)– Perturbed parameter approach (RT1)

Links with other RTs

RT2ART4RT5RT6

RT2BRT3

RT1

RT7

New models and methods

Updated scenarios Boundary

conditions

Simulated

datasets

Organization of the work

Stream 1– Year 1-2

• Use existing coupled models

• Standard methods for simulations

• Use scenarios from IPCC

Stream 2– Year 3-4

• Improved earth system models (RT1)

• Methods of ensemble generation (RT1)

• Updated scenarios (RT7)

Combination of atmosphere-ocean models used to produce the multidecal coupled simulations in RT2A first stream

Partners Atmosphere Resolution Lev Ocean Resol. lev

METO-HC HC-AGCM 1.25x1.875° 38 HC-OGCM 0.33-1° 40

IPSL

UCL-ASTR

LMDZ-4 2.5x3.75° 19 ORCA 0.5-2° 31

MPI ECHAM5 T63 31 MPI-OM 1.5° 40

FUB EGMAM T31 39 EGMAM 0.5-2.8° 20

CNRM ARPEGE T63 45 OPA8 0.5-2° 31

NERSC ARPEGE T63 31 MICOM 1.2° 36

DMI DKC T159 31 - - -

Scénarios GIEC

200

400

600

800

1000

1200

1800 1850 1900 1950 2000 2050 2100 2150 2200

année

CO

2 (p

pmv)

Ctrl

20C3M

A1B

B1

CMIP

A2

IPCC scenarios (TAR)

2xCO2

4xCO2

A2

A1B

B1

historical

Control

Advancement of coupled simulations in RT2A first stream (9-th February 2005)

Partners Control historical B1 A1B A2

METO-HC ? ? ? ? ?

IPSL 200 y 1860-2000 (x2) Done Done Done (2)

MPI 506 y 1860-2000 (x3) Done (3)

Done (3) Done (3)

FUB Testing

CNRM 430 y 1860-2000 Done Done Done

NERSC 150 y 1850-2000 Started Started No

DMI 1860-1919

2m air temperature (Control)

285

286

287

288

289

290

0 50 100 150 200 250 300 350 400 450 500

year

T2

m (

K)

CNRM

IPSL

MPI

BCM

RT2A control simulations global annual mean air temperature at 2m height

RT2A historical simulations global annual mean air temperature at 2m height

2M air temperature

285

286

287

288

289

290

1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000year

T2

m (

K)

CNRM

IPSL

IPSL (naer)

MPI-1

MPI-2

MPI-3

DMI

Jones et al

ERA40

BCM

RT2A A2 scenario global annual mean air temperature (2m)

2M air temperature (scenario A2)

287

288

289

290

291

292

293

2001 2011 2021 2031 2041 2051 2061 2071 2081 2091

year

T2m

(K

)

CNRM

IPSL

IPSL.naer

MPI.1

MPI.2

MPI.3

DMI

A2 scenario t2m anomalies(difference from 1971-2000 climatology for each model)

A2 (anomaly 1971-2000)

-0.50

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100

year

t2m

CNRM

MPI.1

MPI.2

MPI.3

IPSL

IPSL.naer

B1 scenario t2m anomalies

B1 (anomaly 1971-2000)

-0.50

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100

year

t2m

CNRM

MPI.1

MPI.2

MPI.3

IPSL

A1B scenario t2m anomalies

A1B (anomaly 1971-2000)

-0.50

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100

year

t2m

CNRM

MPI.1

MPI.2

MPI.3

IPSL

RT1: Version 1 of Ensemble Prediction System

• Recommended design by month18, specified system by month 24.

• Will be used by RT2A to generate a second stream of “production” global climate simulations in years 3 and 4

• Will comprise separate systems for seasonal to decadal and multi-decadal prediction

• Following slides show runs planned and in progress to test ideas for Version 1 of the multi-decadal system.

• Basic idea: Compare the transient responses in a multi-model ensemble generated by RT2A during months 1-18 against those in a “perturbed parameter” ensemble based on HadCM3

• The perturbed physics ensemble will consist of:

• 1860-2100 simulations with 16 HadCM3 versions with multiple perturbations to uncertain surface and atmospheric parameters

• Augmented by additional pseudo-transient simulations obtained by scaling the equilibrium responses of 128 2xCO2 simulations of the “slab” version of HadCM3 with perturbed parameters

• The 128 member slab ensemble has already been run. The 16 member HadCM3 ensemble is being generated.

Defining Version 1 of the Centennial System

Parameter Perturbations

Large Scale Cloud

Ice fall speed

Critical relative humidity for formation

Cloud droplet to rain: conversion rate and threshold

Cloud fraction calculation

Convection

Entrainment rate

Intensity of mass flux

Shape of cloud (anvils) (*)

Cloud water seen by radiation (*)

Radiation

Ice particle size/shape

Cloud overlap assumptions

Water vapour continuum absorption (*)

Boundary layer

Turbulent mixing coefficients: stability-dependence, neutral mixing length

Roughness length over sea: Charnock constant, free convective value

Dynamics

Diffusion: order and e-folding time

Gravity wave drag: surface and trapped lee wave constants

Gravity wave drag start level

Land surface processes

Root depths

Forest roughness lengths

Surface-canopy coupling

CO2 dependence of stomatal conductance (*)

Sea ice

Albedo dependence on temperature

Ocean-ice heat transfer

Climate sensitivity in a large perturbed parameter ensemble

Red histogram shows results from a ensemble of 128 HadSM3 (slab) model versions designed to produce good present day climate simulations while maximising coverage of parameter space and climate sensitivityBlack histogram shows results from an earlier 53member ensemble (Murphy et al 2004) with perturbations to one parameter at a time.

Multiple parameter perturbations (128 runs)

Single parameter perturbations (53 runs)

HadCM3 perturbed parameter experiments

Ensemble of 16 HadCM3 members:

Members sub-selected from the 128 member HadSM3 ensemble.

Ensemble designed to consist of members which produce good simulations of present climate while

maximising the coverage of parameter space and the range of possible climate sensitivities.

HadCM3 perturbed parameter experiments:Experimental design for a single ensemble member

• Haney forced spin-up

• Flux corrected control

• Historical forcings run (natural and anthro forcings)

• 2000-2100 driven by SRES A1B, plus maybe one additional SRES scenario

We need large ensembles of 21st century simulations.

Too expensive to run 128 HadCM3 versions, so…

Calibrate scaling relationships between the equilibrium response and the 21st century response using 16 HadCM3 versions.

Can then generate a large ensemble of pseudo-HadCM3 simulations from the 128 member ensemble of equilibrium simulations

Towards probabilities for regional climate change during the 21st century

NW Europe surface temperature for 1860-2100 inferred by scaling from equilibrium responses of 128 ensemble members

Early illustration of possible results

Evaluating Centennial Ensemble Prediction Systems

• Predictions cannot be verified• So how will we assess possible designs for the

ensemble prediction system ?

We should sample the widest possible range of modelling uncertainties

We should sample the space consistent with observational uncertainties

Sampling modelling uncertainties (1):In RT1 we will…

Compare HadSM3 perturbed parameter ensembles of a limited size against multi-thousand member ensembles which sample parameter space more thoroughly (climateprediction.net)

Develop facility to run perturbed parameter ensembles with a different GCM (EGMAM)

e.g., comprehensive sampling of multiple parameter perturbations can generate a wide range of climate sensitivities, Stainforth et al, 2005

1% per year CO2 increase

Sampling modelling uncertainties (2)

CMIP2 multi-model ensemble

HadCM3 ensemble with perturbed parameters

HadCM3 perturbed param ensemble already run with 1% per year CO2 forcingCan compare the results against an existing multi-model ensemble