paleoclimate models (chapter 12)
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Paleoclimate ModelsPaleoclimate Models
(Chapter 12)(Chapter 12)
The Climate SystemThe Climate System
(IPCC TAR, Ch. 1)
The Climate SystemThe Climate System
(IPCC TAR, Ch. 1)
Feedbacks
Internal couplings through linking processesAmplify or diminish initial induced climate change
Adjustment Time ScalesAdjustment Time Scales
300-3000 yr
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
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
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
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
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)
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)
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)
Intermediate Intermediate ModelsModels
Simulation Simulation versus versus observationsobservations
(Crucifix et al., 2002)(Crucifix et al., 2002)
Intermediate ModelsIntermediate Models
(Crucifix et al., 2002)(Crucifix et al., 2002)
Intermediate Intermediate ModelsModels
Prescribed ChangesPrescribed Changes
(Crucifix et al., 2002)(Crucifix et al., 2002)
Intermediate Intermediate ModelsModels
Prescribed ChangesPrescribed ChangesandandResponsesResponses
(Crucifix et al., 2002)(Crucifix et al., 2002)
Intermediate Intermediate ModelsModels
ResponseResponse
(Crucifix et al., 2002)(Crucifix et al., 2002)
Intermediate Intermediate ModelsModels Prescribed Changes - Prescribed Changes -
SensitivitySensitivity
(Crucifix et al., 2002)(Crucifix et al., 2002)
Intermediate Intermediate ModelsModels
SensitivitySensitivity
(Crucifix et al., 2002)(Crucifix et al., 2002)
Global Climate ModelsGlobal Climate Models
Global Climate ModelsGlobal Climate Models
Differing scales: distributed surface properties
PBL
ATMOS
SVAT
Export throughStreamflow
SW/GW
External Forcing
CLASP
Global Climate ModelsGlobal Climate Models
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)
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
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
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
(Kutzbach et al., 1998)(Kutzbach et al., 1998)
GCM GCM SimulationSimulation
GCM GCM SimulationSimulation
(Kutzbach et al., 1998)(Kutzbach et al., 1998)
• 25-yr simulation25-yr simulation
• Last 5 yr analyzed Last 5 yr analyzed
GCM GCM SimulationSimulation
(Kutzbach et al., 1998)(Kutzbach et al., 1998)
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)
SpruceSpruceGCM GCM SimulationSimulation
(Bartlein et al., 1998)(Bartlein et al., 1998)
Douglas Douglas FirFir
SagebrushSagebrush
Present-Day Present-Day ResultsResults
GCM GCM SimulationSimulation
(Bartlein et al., 1998)(Bartlein et al., 1998)
Changes Changes with with ClimateClimate
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
PMIP: LGM vs. Present DayPMIP: LGM vs. Present Day
(Pinot et al., 1999)
GCM GCM SimulationSimulation
(Pinot et al., 1999)
GCM GCM SimulationSimulation
PMIP: PMIP: Present DayPresent Day
Sea-surface temperature
Land-surface temperature
(Pinot et al., 1999)
GCM GCM SimulationSimulation
PMIP: PMIP: Present DayPresent Day
(Pinot et al., 1999)
GCM GCM SimulationSimulation
PMIP: PMIP: Present DayPresent Day
Ocean precipitation
Land precipitation
PMIP: LGM vs. PD PMIP: LGM vs. PD (30 S - 30 N)(30 S - 30 N)
(Pinot et al., 1999)
GCM GCM SimulationSimulation
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
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)
(Pinot et al., 1999)
GCM GCM SimulationSimulation
PMIP: LGM-PDPMIP: LGM-PDComparison with proxiesComparison with proxies
Paleoclimate Model Paleoclimate Model Intercomparison Intercomparison Project:Project:Tropical Changes @ Tropical Changes @ LGMLGM
GCM GCM SimulationSimulation
Model changes vs. pollen record
Coldest month temperature
Paleoclimate Model Paleoclimate Model Intercomparison Project:Intercomparison Project:Tropical Changes @ LGMTropical Changes @ LGM
GCM GCM SimulationSimulation
Model changes vs. pollen record
Annual surface temperature
Precipitation changes vs. lake records prescribed SST models
Precipitation changes vs. lake records computed SST models
Paleoclimate ModelsPaleoclimate Models
(Chapter 12)(Chapter 12)
ENDEND
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