Transcript Document

Overview of the CCSM
CCSM Software Engineering Group
[email protected]
June 29 2002
www.ccsm.ucar.edu
What is CCSM?
CCSM is a coupled climate model for
simulating the earths climate system.
www.ccsm.ucar.edu
CCSM Components
CAM2 AGCM
atm
datm (cycling climate data)
CLM
lnd dlnd
Coupler
docn (cycling SST data)
ocn
POP OGCM
www.ccsm.ucar.edu
dice
CSIM
ice
CCSM Component Models
Atmosphere:
NCAR CAM2
– T42 26 levels
– 1-D decomposition (64pe limit)
– Improved Dynamics, Radiation and
Parameterizations
Ocean: Parallel Ocean Program (POP1.4.3)
– ~1 degree horizontal grid
– 40 levels
– 2-D data decomposition
www.ccsm.ucar.edu
CCSM Component Models
Sea-Ice:
CSIM4
– Elastic-viscous-plastic (EVP) dynamics, ice
thickness distribution & energy conserving
thermodynamics
– High/Low resolutions on POP grids
Land:
Community Land Model (CLM2)
– Global Land surface model
– 10 vertical soil layers, 128x64 horizontal points
– 16 different vegetated types
– Surface hydrology and river runoff
www.ccsm.ucar.edu
Previous CSM1 and PCM Simulations
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greenhouse gas and sulfate aerosol forcing
1870 control simulation
Historical 1870 to present
IPCC “Business as Usual” assumption
IPCC stabilization assumption
Multi-member ensembles
Solar variability simulation-ensemble of 4
www.ccsm.ucar.edu
Current CCSM2 Runs
• Control (600 years)
• 1%/year CO2 increase
• Constant 2x CO2
• Control with T85 atm
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High Resolution Atmosphere Simulation
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Climate Models
Expense and work involved with climate
predictions and the pretty pictures
that result adds an aura of truth to
climate model output
Don't be fooled….
Climate models are only sophisticated tools,
not crystal balls.
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Climate Model
Given the size of the problem and the finite amount of
computer power that can be brought to bear,
compromises have to be made.
Some important physical processes cannot be
represented explicitly. They must be represented
approximately by numerical “parameterizations.”
Parameterizations are approximations and are not
exact. Different parameterizations produce some of
the differences in the simulations of different climate
models.
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Model Equilibrium
Model Climate = Real Climate!!!
Real
Climate
Model
Climate
X
Adjustment
Steady State Solution
Time
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Climate Change Processes
Rate of change & variance should be equal
Real Climate
X
Model Climate
A
E
Climate Change Process
Time
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CCSM is considered
to be a solid model
by the scientific
community
Distributed Involvement
CCSM is a large community project:
NSF / National Center for Atmospheric Research
Significant collaborations with:
– US university community
– US Department of Energy (DOE)
• LANL, LLNL, LANL, ORNL, ANL, LBL, NERSC
– National Air and Space Administration (NASA)
www.ccsm.ucar.edu
CCSM Working Groups
Scientific development via working groups
Atmosphere Model
Ocean Model
Land Surface
Polar Model
Climate Variability
Paleoclimate
Biogeochemistry
Climate Change and Assessment
Software Engineering
Annual CCSM Workshop in Breckenridge Colorado
www.ccsm.ucar.edu
How can you get involved?
• Take part in the CCSM working groups
• Feel free to change the code for your own uses, but
be sure to validate your science
• Don't be afraid to debug problems yourself
• Take advantage of your local sysadmins and NCAR
consultants to fix problems
• If the problem is clearly with the model, check the
known bugs area & CCSM Forum, then contact
[email protected]
www.ccsm.ucar.edu