Mechanisms of Interannual Variability in the Ocean Carbon System

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Mechanisms of Interannual Variability in the
Ocean Carbon System
Scott Doney (WHOI) Ivan Lima David Glover
(WHOI) K. Lindsay, N. Mahowald C. Nevison
(NCAR) K. Moore (UCI) Matt Maltrud (LANL) N.
Gruber and N. Lovenduski (UCLA) J. Carton (U.
Maryland), R. Feely (NOAA)
Supported by NOPP (ONR/NSF), NOAA, and NASA
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-Global ocean hindcast simulations
(1958-2004) -ENSO and Southern Annular Mode
(SAM) -Partitioning of d/dt flux, pCO2, and
DIC -DIC, sea surface height altimetry
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Global Ocean Hindcast Simulations (1958-2004)
-WHOI/NCAR/Irvine multi-functional group,
multi-nutrient ecosystem model (Moore et al.,
2004) -Coupled to full-depth ocean BGC model
(CCSM-POP) -Surface physics forcing (1957-2004)
from NCEP reanalysis and satellite products
(Yeager and Large, 2004) -Time-varying
atmospheric dust/iron deposition (NCAR/MATCH
simulations) -Fixed pre-industrial atmospheric
CO2 (280 ppm) transient anthropogenic CO2
simulations
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Mean Air-Sea CO2 Flux
Data Takahashi et al. (2006)
CCSM Model Climatology
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Ocean Carbon Interannual Variability Eq. Pacific
Observations
WHOI Model
Feely et al.
(positive anomaly into ocean)
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Tropical Pacific CO2 Variability
physics
air-sea flux
export
LeQuere 0.4 (70 Eq. Pac.) Obata 0.23 (gt50
Eq. Pac. 30
SO) -Thermocline depth variation subsurface
iron supply -Corresponding changes in
productivity, biomass, community structure -DIC
supply (dominant) export out of phase -General
agreement among field data, ocean models
top-down atmospheric estimates for Eq. Pacific
Obata et al. (2003)
ocean model
data
Obata et al. (2003)
atmosphere
Bousquet et al. (2000)
Le Quere et al. (2000)
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Southern Annular Mode (SAM) Regression Patterns
GEOPOTENTIAL HEIGHT (m)
WINDSTRESS (dyne cm-2)
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SAM and CO2 Flux Variability
NCAR CCSM (FGM)
REGRESSION (mol m-2 yr-1)
CORRELATION
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Linear decomposition X ltXgt
X time-mean anomaly Monthly anomalies
from seasonal climatology
Two variable case XY ltXYgt (XY) (XY)
ltXgtY XltYgt XY
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nDIC
Temp
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nAlk
Freshwater
Eq. Pacific
Regression slope ?x 1 driving term 0 minor
term lt0 compensating term
Spatial maps of
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Annual inventory change ?I/?t Q air-sea
fluxes F dilution/evap A
mean advection E param. eddies
P net comm. prod. other
Q
F
0
E
A
?I
100
P
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Satellite and in-situ proxies for IDIC
-Heat content -Sea surface height -Oxygen
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Sea surface height (altimetry) and Argo (T,S)
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Physics Only
Dust Only
Dust Only
Physics Only
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Ocean Imprint on Atmosphere CO2
Nevison et al. submitted
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Summary

• -Regional partitioning of factors driving air-sea
  CO2 flux
• Wind speed variability (Eq. Pacific, Southern
  Ocean)
• Subtropics thermal effects on ?pCO2
• Tropics/high latitude circulation ( biology) on
  nDIC
• Tropical Indo-Pacific freshwater
• -Large Southern Ocean signal associated with SAM
  and changes in upwelling
• -Improved physical circulation is key to
  resolving ocean carbon variability (e.g.,
  Altimetry, Argo, ORION, data assimilation)

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