Transcript Integrated Climate Change Research: The role of the

Integrated Climate Change Research: The role of
the Community Climate System Model (CCSM)
Jim Hurrell
Director
Climate and Global Dynamics Division
NSF Briefing
February 27, 2007
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Themes of the CGD Scientific Program
Climate Analysis: Diagnostic, Theoretical and Modeling Studies
Development and Evaluation of Community Climate Models
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The Community Climate System Model:
A Framework for Collaborative Research
Scientific Objectives
•
Develop a comprehensive climate model to
study the Earth’s climate.
•
Investigate seasonal and interannual
variability in the climate.
•
Explore the history of Earth’s climate.
•
Estimate the future of the environment for
policy formulation.
Recent Accomplishments
•
Release of a new version (CCSM3) to the
climate community.
•
Studies linking SST fluctuations, droughts,
and extratropical variability.
•
Simulations of last 1000 years, Holocene,
Last Glacial Maximum, and Permian.
•
Creation of largest ensemble of simulations
for the IPCC AR4.
http://www.ccsm.ucar.edu
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Organization of the CCSM Project
CCSM
Advisory
Board
CCSM SSC
Atmosphere
Model
Working
Group
Ocean
Model
Working
Group
Paleoclimate
Working
Group
Climate
Variability
Working
Group
Management
Land Model
Working
Group
Polar
Climate
Working
Group
Chemistry
Climate
Working
Group
Biogeochemistry
Climate
Change
Working
Group
Working
Group
Software
Engineering
Working
Group
Components
Applications
CCSM Features
• CCSM is a collection of active and prescribed forcing (“data”)
components, providing the user with the unique capability to
run all active components or mixtures of active and data
components; e.g.,
– Active ocean can be run with prescribed ice, atmosphere
and land runoff forcing
• used for evaluation of new ocean science
• Runs on multiple platforms (vector and scalar architectures)
– IBM-SP, Linux Clusters, Cray X1, Cray XT3, NEC, Earth
Simulator, SGI Altix, IBM BlueGene/L
• Supports a wide variety of grid resolutions
– Coarser resolutions used for paleo simulations, higher
T85 x 1
resolutions for IPCC type of simulations.
CCSM: a Tool to Study Modal Variability
NAO Impacts on Ecosystems
Marine
Drinkwater et al. (2003)
What Climate Processes Govern NAO Variability?
• 200 years of CCM3 without variations
EOF1 SLP
(Dec-Mar)
in “external” forcings
• Basic structure & time scale arises
from internal nonlinear atmospheric
dynamics
Simulated (Dec-Mar)
Random and Unpredictable
Variations
What Climate Processes Govern NAO Variability?
• 200 years of CCM3 without variations
EOF1 SLP
(Dec-Mar)
in “external” forcings
• Basic structure & time scale arises
from internal nonlinear atmospheric
dynamics
Simulated NAO Index
Random and Unpredictable
Variations
r (1yr) = -0.07
Consistent with Observations
Observed
Observed
(Climate Noise Paradigm)
r (1yr) = -0.06
r (1yr) = 0.4
Except for the latter half
of the 20th Century
A role for external forcing?
The Role of Ocean Forcing
JFM 500 hPa Height Trend (1950-1999) m
Observed
Hurrell et al. (2004);
Hoerling et al. (2004)
Falls
Global SST
Rises
Tropical SST
The Role of the Cryosphere
Sea Ice Forcing
Land Snow Cover
ICE REMOVED
ICE ADDED
500 hPa Z Response
Cohen et al. 2007
Deser et al. 2003
Leveraging the NRCM initiative
The community has identified the requirement for alternative
approaches to:
• Improve the understanding of scale interactions and
approaches to represent multi-scale processes
• Address climate model biases (particularly tropical biases and
precipitation biases)
• Improve climate predictions at the regional scale (water cycle,
extreme events such as hurricanes, and their impacts)
• Improve predictions of the regional earth system for research
and applications (e.g., water, land, air, carbon management)
NRCM: Proposed Modeling Framework
WRF
CAM
CLM
ROMS
ROMS
POP
OCEAN NRCM
Motivation : CCSM3 SST BIAS
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Large-Scale Effects of DSST < 0 off
North/South America and South Africa
P in Control
DP