Download - Paleoclimate Models (Chapter 12)
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Paleoclimate ModelsPaleoclimate Models
(Chapter 12)(Chapter 12)
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The Climate SystemThe Climate System
(IPCC TAR, Ch. 1)
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The Climate SystemThe Climate System
(IPCC TAR, Ch. 1)
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Feedbacks
Internal couplings through linking processesAmplify or diminish initial induced climate change
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Adjustment Time ScalesAdjustment Time Scales
300-3000 yr
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Climatic Variation and ChangeClimatic Variation and ChangeAdditional FactorsAdditional Factors
1.1. Abrupt changeAbrupt change- external conditions (e.g., solar output)external conditions (e.g., solar output)- internal feedbacksinternal feedbacks- passing a threshold (e.g. ice caps passing a threshold (e.g. ice caps
melting)melting)
2. Multiple climate states from the same 2. Multiple climate states from the same external conditionsexternal conditions
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How can a numerical model How can a numerical model represent all of this?represent all of this?
Options:Options:
• “ “Full” complexity - short time scalesFull” complexity - short time scales
• Simplified - long time scalesSimplified - long time scales
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Simplified ModelsSimplified Models• Climate simulation in general - 1960sClimate simulation in general - 1960s
• Paleoclimate applications: Paleoclimate applications:
Barry Saltzman (1931-2001)Barry Saltzman (1931-2001)
e.g., Saltzman & Maasch (1991)e.g., Saltzman & Maasch (1991)
€
dIdt
= α 1 − α 2cμ − α 3I − α 2κθθ − α 2κθ R(t)
dμdt
= β1 − (β2 − β3θ + β4θ 2)μ − (β5 − β6θ)θ
dθdt
= γ1 − γ2I − γ3θ
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Simplified ModelsSimplified Models• Three-variable model for slow climate variability:Three-variable model for slow climate variability:
I = ice mass, I = ice mass, = atmospheric CO = atmospheric CO22, , = mean ocean = mean ocean temperaturetemperature
R(t) = solar variation at 65 ˚NR(t) = solar variation at 65 ˚N
ii, , ii, , II - constants that can distill into 7 tunable parameters - constants that can distill into 7 tunable parameters€
dIdt
= α 1 − α 2cμ − α 3I − α 2κθθ − α 2κθ R(t)
dμdt
= β1 − (β2 − β3θ + β4θ 2)μ − (β5 − β6θ)θ
dθdt
= γ1 − γ2I − γ3θ
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Simplified ModelsSimplified Models• Three-variable model for slow climate variability:Three-variable model for slow climate variability:
(Saltzman, 1986)(Saltzman, 1986)
COCO22 parameter ( parameter (): ):
from from 1313C core data (dashed) and simulation (solid)C core data (dashed) and simulation (solid)
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Simplified ModelsSimplified Models• Three-variable model for slow climate variability:Three-variable model for slow climate variability:
(Saltzman, 1986)(Saltzman, 1986)
1818O: O:
from SPECMAP from SPECMAP 1818O (dashed) and simulation (solid)O (dashed) and simulation (solid)
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Intermediate ModelsIntermediate Models Global, 2-5 dimensional model:Global, 2-5 dimensional model:• 5˚ latitudinal bands5˚ latitudinal bands• In each bandIn each band
- 2 continental sectors (Eurasia-Africa, Americas)2 continental sectors (Eurasia-Africa, Americas)- 3 ocean sectors (Atlantic, Indian, Pacific)3 ocean sectors (Atlantic, Indian, Pacific)
• Circulation dynamics: 2-level, Q-G Circulation dynamics: 2-level, Q-G - winds at 250 hPa, 750 hPawinds at 250 hPa, 750 hPa- temperature at 500 hPatemperature at 500 hPa- plus - Hadley Cell transport in tropicsplus - Hadley Cell transport in tropics
• 2-D ocean model for each basin2-D ocean model for each basin• Land-atmosphere coupling processes Land-atmosphere coupling processes (Crucifix et al., 2002)(Crucifix et al., 2002)
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Intermediate Intermediate ModelsModels
Simulation Simulation versus versus observationsobservations
(Crucifix et al., 2002)(Crucifix et al., 2002)
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Intermediate ModelsIntermediate Models
(Crucifix et al., 2002)(Crucifix et al., 2002)
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Intermediate Intermediate ModelsModels
Prescribed ChangesPrescribed Changes
(Crucifix et al., 2002)(Crucifix et al., 2002)
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Intermediate Intermediate ModelsModels
Prescribed ChangesPrescribed ChangesandandResponsesResponses
(Crucifix et al., 2002)(Crucifix et al., 2002)
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Intermediate Intermediate ModelsModels
ResponseResponse
(Crucifix et al., 2002)(Crucifix et al., 2002)
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Intermediate Intermediate ModelsModels Prescribed Changes - Prescribed Changes -
SensitivitySensitivity
(Crucifix et al., 2002)(Crucifix et al., 2002)
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Intermediate Intermediate ModelsModels
SensitivitySensitivity
(Crucifix et al., 2002)(Crucifix et al., 2002)
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Global Climate ModelsGlobal Climate Models
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Global Climate ModelsGlobal Climate Models
Differing scales: distributed surface properties
PBL
ATMOS
SVAT
Export throughStreamflow
SW/GW
External Forcing
CLASP
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Global Climate ModelsGlobal Climate Models
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GCM SimulationGCM Simulation
Paleo-Simulation Projects:Paleo-Simulation Projects: Cooperative Holocene Mapping Project Cooperative Holocene Mapping Project
(COHMAP)(COHMAP)
COHMAP extensionCOHMAP extension
Paleoclimate Model Intercomparison Project Paleoclimate Model Intercomparison Project (PMIP)(PMIP)
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GCM SimulationGCM SimulationCooperative Holocene Mapping Project (COHMAP)Cooperative Holocene Mapping Project (COHMAP)NCAR CCM0NCAR CCM0Prescribed changes inPrescribed changes in
- InsolationInsolation- SSTSST- Ice sheetsIce sheets- COCO22
Time slices every 3,000 yr (18k BP, 15k BP, …)Time slices every 3,000 yr (18k BP, 15k BP, …) Perpetual January or JulyPerpetual January or July
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GCM SimulationGCM Simulation
Cooperative Holocene Mapping Project (COHMAP)Cooperative Holocene Mapping Project (COHMAP)
Ice sheets & cold ocean Ice sheets & cold ocean
colder, drier climatecolder, drier climate
intensified jet streamintensified jet stream
Amplified annual cycleAmplified annual cycle
Intensified summer monsoonsIntensified summer monsoons
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GCM SimulationGCM SimulationCOHMAP ExtensionCOHMAP ExtensionNCAR CCM1NCAR CCM1 ComputedComputed
- SST (slab ocean, prescribed heat transport)SST (slab ocean, prescribed heat transport)- Sea iceSea ice- Soil moistureSoil moisture- Seasonal snowSeasonal snow
Time slices every ~ 3,000 yrTime slices every ~ 3,000 yr Full annual cycle simulatedFull annual cycle simulated
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(Kutzbach et al., 1998)(Kutzbach et al., 1998)
GCM GCM SimulationSimulation
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GCM GCM SimulationSimulation
(Kutzbach et al., 1998)(Kutzbach et al., 1998)
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• 25-yr simulation25-yr simulation
• Last 5 yr analyzed Last 5 yr analyzed
GCM GCM SimulationSimulation
(Kutzbach et al., 1998)(Kutzbach et al., 1998)
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Longitudinal Longitudinal average average overturning overturning circulation circulation
(mean (mean meridional meridional circulation)circulation)
GCM SimulationGCM Simulation
(Kutzbach et al., 1998)(Kutzbach et al., 1998)
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SpruceSpruceGCM GCM SimulationSimulation
(Bartlein et al., 1998)(Bartlein et al., 1998)
Douglas Douglas FirFir
SagebrushSagebrush
Present-Day Present-Day ResultsResults
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GCM GCM SimulationSimulation
(Bartlein et al., 1998)(Bartlein et al., 1998)
Changes Changes with with ClimateClimate
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Paleoclimate Model Paleoclimate Model Intercomparison Project:Intercomparison Project:Tropical Changes @ LGMTropical Changes @ LGM
• 17 GCMs17 GCMs- 9 slab ocean9 slab ocean
- 8 prescribed SST8 prescribed SST
• Prescribed changes inPrescribed changes in
- insolation- insolation
- CO- CO22
- ice sheets- ice sheets
GCM GCM SimulationSimulation
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PMIP: LGM vs. Present DayPMIP: LGM vs. Present Day
(Pinot et al., 1999)
GCM GCM SimulationSimulation
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(Pinot et al., 1999)
GCM GCM SimulationSimulation
PMIP: PMIP: Present DayPresent Day
Sea-surface temperature
Land-surface temperature
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(Pinot et al., 1999)
GCM GCM SimulationSimulation
PMIP: PMIP: Present DayPresent Day
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(Pinot et al., 1999)
GCM GCM SimulationSimulation
PMIP: PMIP: Present DayPresent Day
Ocean precipitation
Land precipitation
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PMIP: LGM vs. PD PMIP: LGM vs. PD (30 S - 30 N)(30 S - 30 N)
(Pinot et al., 1999)
GCM GCM SimulationSimulation
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Paleoclimate Model Paleoclimate Model Intercomparison Project:Intercomparison Project:Tropical Changes @ LGMTropical Changes @ LGM
GCM GCM SimulationSimulation
Top: Sfc T change - prescribed SST
Bottom: Sfc T change - computed SSTRMS spead among models
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Paleoclimate Model Paleoclimate Model Intercomparison Project:Intercomparison Project:Tropical Changes @ LGMTropical Changes @ LGM
GCM GCM SimulationSimulation
Difference in simulated SST changes from reconstructed changes (LGM-PD)
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(Pinot et al., 1999)
GCM GCM SimulationSimulation
PMIP: LGM-PDPMIP: LGM-PDComparison with proxiesComparison with proxies
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Paleoclimate Model Paleoclimate Model Intercomparison Intercomparison Project:Project:Tropical Changes @ Tropical Changes @ LGMLGM
GCM GCM SimulationSimulation
Model changes vs. pollen record
Coldest month temperature
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Paleoclimate Model Paleoclimate Model Intercomparison Project:Intercomparison Project:Tropical Changes @ LGMTropical Changes @ LGM
GCM GCM SimulationSimulation
Model changes vs. pollen record
Annual surface temperature
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Precipitation changes vs. lake records prescribed SST models
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Precipitation changes vs. lake records computed SST models
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Paleoclimate ModelsPaleoclimate Models
(Chapter 12)(Chapter 12)
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