the philosophy of climate modeling jeffrey t. kiehl climate change research section ncar jeffrey t....
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The Philosophy of Climate ModelingThe Philosophy of Climate Modeling
Jeffrey T. KiehlClimate Change Research
SectionNCAR
Jeffrey T. KiehlClimate Change Research
SectionNCAR
OutlineOutline
Philosophy & Climate Modeling Climate Science Finding a Research Problem Why Model the Climate System? The Way of Climate Modeling Summary
Philosophy & Climate Modeling Climate Science Finding a Research Problem Why Model the Climate System? The Way of Climate Modeling Summary
Philosophy & Climate Modeling
Philosophy & Climate Modeling
Epistemology - What can we know? Models as representations
Metaphysics - What is? How real are the representations?
Ethics - What is Good/Evil? What do we choose to present?
Aesthetics - What is Beauty? How do we present our results?
Politics - Ethics of Groups What are the social implications of our results?
Epistemology - What can we know? Models as representations
Metaphysics - What is? How real are the representations?
Ethics - What is Good/Evil? What do we choose to present?
Aesthetics - What is Beauty? How do we present our results?
Politics - Ethics of Groups What are the social implications of our results?
Climate ScienceClimate Science
Forcing Feedbacks Response
Variability
We all fit in here somewhere!
Finding a Research Problem
Finding a Research Problem
Something that Really Grabs You (Follow Your Bliss)
Tractable (be aware of timescales involved, complexity of system)
Affordable (can you pay for it?)
Valuable (to whom?)
Something that Really Grabs You (Follow Your Bliss)
Tractable (be aware of timescales involved, complexity of system)
Affordable (can you pay for it?)
Valuable (to whom?)
Why Model the Climate System?
Why Model the Climate System?
Develop a fundamental understanding of Earth’s climate system (What Ifs)
To look at mechanisms in the system To look at interactions within the system To replicate reality (past, present, future)
To provide information for policy decisions
Can you think of others?
Develop a fundamental understanding of Earth’s climate system (What Ifs)
To look at mechanisms in the system To look at interactions within the system To replicate reality (past, present, future)
To provide information for policy decisions
Can you think of others?
Climate What IfsClimate What Ifs
What if the solar output decreased? What if there were no mountains? What if Earth rotated twice as fast? What if aerosol loading doubled? What if cloud drop size decreased? What if tropical forests disappeared?
What if the solar output decreased? What if there were no mountains? What if Earth rotated twice as fast? What if aerosol loading doubled? What if cloud drop size decreased? What if tropical forests disappeared?
The Way of Climate Modeling
The Way of Climate Modeling
Forming a Question Setting up a simulation Simulation Strategy What do you look for? What can you explain, or not? Looking at the process level Forming a new question
Forming a Question Setting up a simulation Simulation Strategy What do you look for? What can you explain, or not? Looking at the process level Forming a new question
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Forming a QuestionForming a Question
Decides the Model Configuration Individual or Group Needed?
Decides the Model Configuration Individual or Group Needed?
Don’t get involved in partial problems, but always take flightto where there is a free view over the whole single greatproblem, even is the view is still not a clear one.
Ludwig Wittgenstein
Setting up a Simulation
Setting up a Simulation
Boundary Conditions Initial Conditions Model Spin up Defining the control simulation
To tune or not to tune
Boundary Conditions Initial Conditions Model Spin up Defining the control simulation
To tune or not to tune
Energy Balance
Surface Temperature
Sea Ice Area
Spin-up~100 yr
CCSM3T31X3 Control
To Tune or Not?To Tune or Not?
ocean
atmosphere
The great Way is easy,yet people prefer the side paths.Be aware when things are out of balance.
Tao Te Ching 53
ocean
atmosphere
ρCp∂T
∂t≈ 0 ρCp
∂T
∂t> 0
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Net Energy Flux into Earth System
Net Energy Flux into Ocean
Simulation StrategySimulation Strategy
Length of simulation Transient Steady State
Time scales of problem When do you stop the simulation?
Length of simulation Transient Steady State
Time scales of problem When do you stop the simulation?
What do you look for?What do you look for?
Are there optimal metrics? Model versus data Model versus control
Don’t be narrowly focused on a few metrics Global Regional Mean state Variability
How to display your metrics?
Are there optimal metrics? Model versus data Model versus control
Don’t be narrowly focused on a few metrics Global Regional Mean state Variability
How to display your metrics?
What can(‘t) you explain?
What can(‘t) you explain?
Where to look? Budgets and Causality (the chicken and the egg)
What tools are available? Process studies Sensitivity studies Temporal evolution
Where to look? Budgets and Causality (the chicken and the egg)
What tools are available? Process studies Sensitivity studies Temporal evolution
Kiehl and Shields (2005)
Inefficient mixingin Permian ocean indicativeof anoxia
10XCO2
1XCO2
∂ρd∂z
∂ρd∂z
Process StudiesProcess Studies
Temporal Evolution and Correlation
Regional Analysis Sensitivity of Parameterizations
Single Column Model Data Assimilation CAPT: A CAM Forecast Model
Temporal Evolution and Correlation
Regional Analysis Sensitivity of Parameterizations
Single Column Model Data Assimilation CAPT: A CAM Forecast Model
CCPP ARM Parameterization Testbed (CAPT)
Hannay, Williamson, Kiehl
SummarySummary
Big challenges in model biases: Tropical mean state Tropical variability (e.g. ENSO) Cold polar tropopause Continental precipitation High latitude continental temperatures
Big challenges in model biases: Tropical mean state Tropical variability (e.g. ENSO) Cold polar tropopause Continental precipitation High latitude continental temperatures
SummarySummary
Big Challenges Model Processes Fully interactive biogeochemical, atmospheric chemical system model
Regional Simulation of the 20th century climate
Aerosol indirect effect
Big Challenges Model Processes Fully interactive biogeochemical, atmospheric chemical system model
Regional Simulation of the 20th century climate
Aerosol indirect effect
In the beginner’s mind there are many possibilities,but in the expert’s mind there are few.
Shunryu Suzuki