Transcript ppt

The Working Group on Coupled Models (WGCM)
Report to JSC, 2010
Sandrine Bony & Jerry Meehl
WGCM co-chairs
Antalya, Feb 2010
WGCM Mission
Review and foster the development of coupled climate models (and now ESMs)
Coordinate model experiments and inter-comparisons to:
- better understand natural climate variability
- predict the climate response to natural & anthropogenic perturbations
Promote and facilitate model validation and diagnosis of shortcomings
A balance between :
Predicting – Evaluating - Understanding
Coordinated Model Experiments :
CMIP3 : a big boost to climate science
• More than 500
publications
• More than 765 TB
downloaded
• More than 3,000
users
Nov 2004
Jan 2007
(AR4 WGI)
Aug 2009
Courtesy of Bob Drach & Karl Taylor, PCMDI
From CMIP3 to CMIP5 :
What should be improved ?
Better inform decisions on climate change adaptation and mitigation
Integrate Earth System Modelling
Better assess robust and uncertain aspects of climate change
Facilitate model evaluation and assess confidence in model projections
+ improvements on the infrastructure side
… this led to CMIP5
CMIP5 : a framework for climate change modeling over the next 5+ years
Promotes a standard set of model simulations in order to :

evaluate how realistic the models are in simulating the recent past

provide projections of future climate change on two time scales

understand some of the factors responsible for model differences


Two timescales and two sets of science problems

Will be assessed by the IPCC AR5

Taylor et al. 2009, http://cmip-pcmdi.llnl.gov/cmip5/
Near-Term :
(next 3-4 decades)
Long-Term :
(past to 2100 & beyond)
→ decadal climate
predictability
→ evaluation of climate models
(recent past, A-Train, paleo)
→ ocean initialization
→ detection & attribution
→ impact volcanos
→ climate change scenarios
→ regional climate
changes (high resol)
& climate extremes
→ climate sensitivity, radiative
forcing and physical
feedbacks (e.g. clouds)
→ air quality changes
(aerosols, chemistry)
→ biogeochemical feedbacks
(e.g. carbon, chemistry)
CMIP5 : a framework for climate change modeling over the next 5+ years
Promotes a standard set of model simulations in order to :

evaluate how realistic the models are in simulating the recent past

provide projections of future climate change on two time scales

understand some of the factors responsible for model differences


Two timescales and two sets of science problems

Will be assessed by the IPCC AR5

Taylor et al. 2009, http://cmip-pcmdi.llnl.gov/cmip5/
For computationally demanding models : very high
resolution or very complex models, or new generation of
climate models (MMF, global CRMs) :
AMIP
CORE
“time-slice”
Prescribed SST time-slices (1979-2008 + 2026-2035)
+ idealized experiments (e.g. aqua-planet, +4K, 4xCO2)
→ regional effects of climate change
→ explore the impact of higher resolution on
climate simulations : mean & variability, extremes,
AND sensitivity to external perturbations.
An important focus put on model evaluation and understanding...
Example of CMIP5 Long-Term Experiments
Model
All simulations are forced by
Evaluation
prescribed concentrations
except those “E-driven” (i.e.,
emission-driven).
Climate
Projections
ensembles:
AMIP & 20 C
Control,
AMIP, &
20 C
E-driven control &
20 C
RCP4.5,
RCP8.5
E-driven
RCP8.5
1%/yr CO2 (140 yrs)
abrupt 4XCO2 (150 yrs)
fixed SST with 1x & 4xCO2
Coupled carbon-cycle
climate models only
Understanding
... In collaboration with many WCRP/IGBP partners
Example of CMIP5 Long-Term Experiments
Detection-Attribution
(IDAG)
Integrated Assessment
Consortium (IAM),
connection to WG-III
Paleo
(PMIP, IGBP-PAGES)
Cloud and
moist processes
(CFMIP-GCSS
WGNE)
+ Satellite simulators
& process diagnostics
(CFMIP-GCSS)
Chemistry, aerosols
Carbon-climate feedbacks (SPARC, AC&C)
(C4MIP, IGBP-AIMES)
Status and Timeline :
At least 21 global modeling groups will participate in CMIP5. Likely that about 5 groups will have
50 km class AOGCMs for decadal prediction, at least 10 groups will have ESMs, several groups will
have high-resolution AGCMs (<50 km).

• The full sets of forcings and boundary conditions, and the list of model outputs, have been finalized.
• Simulations have now started in many modeling groups.
• Model outputs will be archived on the “Earth System Grid” (distributed grid technology) which is
being deployed and tested now.
• An extensive documentation of the models and of model experiments will be available for CMIP5
through EU Metafor (standardized vocabulary and documentation), and US Earth System Curator
projects (web-based tools for ingesting metadata).
• PCMDI will require agreement to the “terms of use” as part of the registration procedure. CMIP
data will be divided into two classes: unrestricted and restricted-use (no restriction: 7 out of 12).

Analyses of model data will begin late 2010, and will be assessed by the IPCC AR5.

CMIP5 model simulations and analyses will continue well beyond AR5 deadlines.
In parallel to CMIP5,
many other climate model coordinated experiments
are being organized by the modelling community
– WGCM (PMIP, CFMIP..): paleo, clouds
– WGNE/WGCM (Transpose-AMIP): evaluation of climate models in NWP mod
- CLIVAR WGSIP, WGOMD : seasonal to interannual prediction, ocean
– TFRCD (CORDEX) : regional
– GEWEX GCSS (GPCI) : processes
– SPARC & IGBP/IGAC (CCMVal, AeroCom..): chemistry & aerosols
– IGBP/AIMES (C4MIP) : carbon feedbacks
– … and much more!
+ WGNE/WGCM Metrics panel
Proposal for coordinated geo-engineering experiments
with stratospheric aerosols
by Ben Kravitz, Alan Robock et al.
Aim: explore the efficacy and risks of stratospheric geo-engineering with sulfate aerosols.
Demonstration project to be conducted by a few modeling groups. Coordination with SPARC?
Not part of CMIP5. Received some feedback from WGCM last September.
Issues of particular interest :
- robustness of the model responses to geo-engineering
- response of the hydrological cycle, temperature patterns and stratospheric ozone
- response to the stoppage of geoengineering after a few decades
Several experiments proposed for coupled ocean-atmosphere models including interactive
aerosols and chemistry :
- in combination of 1% increase CO2 per year, progressively balance the CO2 radiative forcing
by a reduction of the solar constant
- in combination of RCP 4.5 scenario: progressively balance the CO2 radiative forcing by
injecting stratospheric aerosols (or SO2) at the equator.
- abrupt stoppage of geo-engineering after 50 years
+ simpler idealized experiments to better understand inter-model differences
Interested modeling groups will perform these experiments this year. More groups might
join after this demonstration project. How should this be coordinated across WCRP?
BIG CHALLENGE :
How to improve our confidence in climate models ?
How to assess the credibility of model projections ?
How to gain confidence in GCMs projections ?
(1) Bottom-Up approach : evaluate and improve the physical basis of climate models
through large-scale and process-scale evaluations
High resolution global models
(global CRM, MMF)
Model projections
LES models
Cloud Resolving Models
Single Column
Models
Field campaigns &
instrumented sites
3D-Climate Models
NWP Models
Global observational
datasets
Analysis &
Understanding
climate change
How to gain confidence in GCMs projections ?
(1) Bottom-Up approach : evaluate and improve the physical basis of climate models
through large-scale and process-scale evaluations
(2) Top-Down approach : understand the models' results & identify critical processes
to provide guidance for specific observational tests/process studies
and model improvements
High resolution global models
(global CRM, MMF)
Model projections
LES models
Cloud Resolving Models
Single Column
Models
Field campaigns &
instrumented sites
3D-Climate Models
NWP Models
Global observational
datasets
Analysis &
Understanding
climate change
CMIP5 and associated modeling activities :
an opportunity to develop both approaches,
especially the second one
- Better interpret inter-model differences
in current climate & climate projections
- Evaluate climate models over a wide range of scales and phenomena
i.e. from weather to paleo time scales, from regional to global,
from processes to climate, across all physical and biogeochemical components
- Explore how model formulation and present-day model performance
translate to reliability of climate projections
→ a big challenge and a key focus of WGCM activities over the
next few years, in collaboration with WCRP/IGBP partners
A WGCM project supported by WCRP/CLIVAR and IGBP/PAGES
Coordinated by: P. Braconnot & S. Harrison
with S. Joussaume, B. Otto-Bliesner, A. Abe-Ouchi, A. Haywood, P. Valdes, G.Ramstein,
K. Taylor, P. Bartlein, M. Kucera, J. Jungclaus
Main objectives:
Coordinate paleoclimate modelling activities to :
- Understand the mechanisms of past climate change
- Test whether climate models can represent a climate state
different from the present-day
PMIP – Phase 3
Coordinated model experiments :
Data syntheses :
• PMIP3 / CMIP5 simulations :
- Mid-Holocene (6 ka)
- Last Glacial Maximum (LGM, 21 ka)
- Last Millenium
• Key periods
• Assess uncertainties in past reconstructions
→ using the same model version than for
CMIP5 simulations of present-day and
climate projections !
e.g. Reconstructed SST anomalies at LGM
MARGO: Nature Geoscience 2009
(Taylor et al. 2009)
→ PMIP working groups also focus on other
key periods (e.g. last inter-glacial 130 ka,
Mid-Pliocene 3 Myr ago, etc)
PMIP database and website :
http://pmip2.lsce.ipsl.fr
Constraints on climate sensitivity
Temperature response over different ocean basins at LGM :
+ data
 models
Otto-Bliesner et al. 2009
Polar amplification :
Continental vs ocean response :
Greenland ice core
estimates
Antarctic
ice core
estimates
Masson-Delmotte et al, 2005
LGM
Elevation correction
4xCO2
2xCO2
Laîné et al. 2009
Constraints on the response of
the hydrological cycle
Change in precipitation inferred for Mid-Holocene (6 ka)
over western Africa :
Joussaume et al. 1999
Braconnot et al. 2007
Cloud Feedback Model Inter-comparison Project Phase-2
CFMIP-2 (www.cfmip.net)
A WGCM project coordinated by : Mark Webb, Sandrine Bony,
Christopher Bretherton, Steve Klein, George Tselioudis
Aims :
Encourage coordinated research in the area of cloud-climate feedbacks.
Facilitate the evaluation of clouds simulated by climate models
Strong interactions between climate/process/observation/NWP communities
Building bridges through the cloud communities
Cloud Feedback Model Inter-comparison Project Phase-2
CFMIP-2 (www.cfmip.net)
Understanding
Evaluation
Assessment of cloud-climate feedbacks
Cloud Feedback Model Inter-comparison Project Phase-2
CFMIP-2 (www.cfmip.net)
GCM analysis through
a hierarchy of models
Understanding
Evaluation
Assessment of cloud-climate feedbacks
Cloud Feedback Model Inter-comparison Project Phase-2
CFMIP-2 (www.cfmip.net)
GCM analysis through
a hierarchy of models
Process studies
(in-situ obs, LES/CRMs)
Understanding
Evaluation
Assessment of cloud-climate feedbacks
CFMIP/GCSS/CMIP5 model outputs at selected locations
(118 locations, high-frequency, detailed cloud diagnostics)
SHEBA
Barro
w
Chibolton
SIRTA
Oklahoma
Tibet
GPCI
AMMA
RICO
TOGA-COARE
Darwi
n
ASTEX
GATE
VOCALS
ARM, CEOP, CloudNet instrumented sites
● GPCI / Tropical West & South East Pacific / AMMA transects
● Field experiments / GCSS case studies
● Locations of large inter-model spread of cloud feedbacks (CMIP3)
●
CFMIP-GCSS Study of Cloud Feedback Mechanisms
by using SCM/CRM/LES Models (CGILS, coordinated by Minghua Zhang)
Case studies of PBL cloud feedback mechanisms
Cloud Feedback Model Inter-comparison Project Phase-2
CFMIP-2 (www.cfmip.net)
GCM analysis through
a hierarchy of models
Process studies
(in-situ obs, LES/CRMs)
Understanding
Satellite observations
& simulators (COSP)
Evaluation
Assessment of cloud-climate feedbacks
Cloud Vertical Distribution
CALIPSO-GOCCP
OBS
ECHAM5
+ SIM
CCCMA
+ SIM
LMDZ4
+ SIM
CAM3.5
+ SIM
0.3
Overestimate:
of high clouds
Underestimate of:
- Tropical low clouds
- Congestus clouds
- extratropical mid-level
clouds
0
Chepfer et al. (Calipso-Cloudsat workshop, Jul 2009)
Vertical distributions of radar reflectivities
(CFADs)
CloudSat
(Bodas-Salcedo et al., in preparation)
Observations useful for the evaluation of model clouds through COSP
Link available from www.cfmip.net
Observations for CMIP5 Simulations
• The climate modeling community would greatly benefit from an easier and more
coordinated access to observations for model evaluation and analysis.
• Many individual initiatives worldwide (different MIPs, ARM, etc)
CMIP5 might be an excellent opportunity to foster a coordinated
access to observations that are most useful for model evaluation.
• Recently, JPL (Joao Texeira, Duane Waliser, Jerry Potter, S Boland) launched such
an initiative
- To provide the community of researchers that will analyze CMIP5 simulations
access to analogous sets of observational data.
- Analogous sets in terms of periods, variables, temporal/spatial frequency
- This activity will be carried out in close coordination with CMIP5 & modelling activities
- It will directly engage the observational (e.g. mission and instrument) science teams to
facilitate production of the corresponding data sets.
Discussions already engaged with NASA.
What about other providers of satellite and in-situ observations?
To be discussed with WOAP and GCOS.
Conclusion
Trying to keep the balance between predicting, evaluating and understanding...
CMIP5 :
- many new features : decadal, ESMs, high-resolution, satellite and process outputs..
- strong partnership with WCRP partners and IGBP (joint WGCM-AIMES meeting)
- huge effort for modeling groups and many other communities
Analysis of CMIP5 simulations : an opportunity to
- build connections among modeling communities and between modeling,
processes and observation
- address key science challenges
e.g. assessing the reliability of model projections based on model evaluation
at different time scales. cf IPCC expert meeting on multi-model simulations
- help interpret model deficiencies and guide the model development process
(motivation for the Survey on model evaluation and improvement at last CLIVAR SSG).
Issues for JSC :
- coordination of observations for model evaluation (modeling – WOAP – GCOS panels)
- coordination & syntheses of different MIPs, evaluations and analyses across WCRP & IGBP
- CMIP5 analysis : recommendations? e.g. encourage coordinated analyses and
syntheses about key topics cross-acronyms (strengthen connections + help AR5 authors)
WCRP-WWRP-THORPEX Consultation on
Model Evaluation and Improvement
Sandrine Bony, Jerry Meehl, Anna Pirani (WGCM)
Christian Jakob, Martin Miller (WGNE)
Ben Kirtman (WGSIP), Stephen Griffies (WGOMD), Tony Busalacchi (WCRP)
Background and Goal :
- Model errors and biases are key limitations of the skill of model predictions
over a wide range of time and space scales ;
- Not a new story. The increase of resolution and the addition of complexity in ESMs
have not solved the problem.
- How to tackle the problem ? What should we do? What can we do ?
-> Bottom-up consultation of NWP/climate modeling groups, CLIVAR WGs/panels,
WCRP/WWRP/IGBP projects
- Restructuration of WCRP : an opportunity to put recommendations into action.
More in a few minutes....