Transcript Estimating ocean-atmosphere carbon fluxes from atmospheric oxygen measurements Mark Battle (Bowdoin College) Michael Bender & Nicolas Cassar (Princeton) Roberta Hamme (U BC), Ralph Keeling (SIO) Cindy.

Estimating ocean-atmosphere
carbon fluxes from atmospheric
oxygen measurements
Mark Battle (Bowdoin College)
Michael Bender & Nicolas Cassar (Princeton)
Roberta Hamme (U BC), Ralph Keeling (SIO)
Cindy Nevison (NCAR)
UNESCO
Surface Ocean CO2 Variability and
Vulnerabilities Workshop
April 12, 2007
Funding from:
NSF, NOAA GCRP, BP-Amoco, NASA, UNESCO
On the agenda:
• Oxygen, O2/N2, APO and Carbon Fluxes
• What can (did) one do with APO?
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The ancient past (Keeling, Stephens)
The recent past (Gruber, Tohjima, Battle, Naegler)
The present: Models (Nevison)
The present: Data (Tohjima, Hamme)
The present: Data & Models (Rödenbeck)
What determines the amount
of O2 in the atmosphere?
1st order description of long-term fluxes
More detail on the oceans
Seasonality…
1.4
1.1
More detail on the oceans
Seasonality and secular trends
Atmospheric Potential Oxygen
APO  O2 + 1.1 CO2
APO reflects air/ocean O2 & CO2 fluxes
Land biota doesn’t change APO
Fossil fuels change APO a little
O2/N2 & APO changes are small
O2/N2 per meg  (O2/N2sa – O2/N2st)/(O2/N2st) x106
1 per meg = 0.0001% = 0.001 per mil
1 PgC FF  3.2 per meg O2/N2 0.66per meg APO
1 PgC into oceans  2.5per meg APO*
*assuming no corresponding O2 flux
What controls APO?
• Ocean biology (light, nutrients, etc.)
• Ocean chemistry (O2 & CO2 equilibration)
• Ocean temperature (solubility &
stratification)
• Ocean circulation (shallow & deep)
• Atmospheric transport
• Fossil fuel (a little)
A brief history of time APO
In the beginning…
Stephens et al.,
1998
Models don’t get
interpolar gradient
right (physics?)
Equatorial data
would be nice.
The next chapter…
pCO2, dissolved O2, PO4 &
heat fluxes
fluxes of CO2 and O2
atmospheric transport
atmospheric composition
at observing stations
Gruber et al., 2001
Eliminate OBGC
Model.
Results seem
Independent of
Ocean physics
Interpolar gradient
getting better
Equatorial data
Would be nice.
New data!
Tohjima, et al. 2005
Tohjima, et al. 2005
Still more new data!
Princeton & Scripps data
Battle et al.
2006
Equatorial
bulge is
confirmed…
Battle et al.
2006
Equatorial
bulge is
confirmed…
and the
interpolar
gradient
looks good too.
…but it’s evolving
Battle et al., 2006
…and more modeling work
Naegler et al. 2006
Naegler et al. 2006
Work in progress:
Fresh ideas and fresh data…
C. Nevison (NCAR)
work in progress, with S. Doney & N. Mahawold
•Model study with OBGCM & ATM
•Seasonal cycle comparison
•Annual mean gradient comparison
•Emphasis on quantifying transport errors
Ocean Ecosystem Model+OGCM (Doney)
CASA land bio (also w/ fire)
fossil fuel
fluxes of CO2 and O2
MATCH (NCEP winds 1979-2004)
atmospheric composition
at observing stations
C. Nevison (NCAR)
work in progress, with S. Doney & N. Mahawold
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Ocean O2 and CO2 fluxes from WHOI ecosystem
model.
Set of Carbon/O2 fluxes with IAV in ocean, land and
transport, all NCEP driven
MATCH has stronger rectifier than ATMs previously
used (TM3, TM2, GCTM)
Seasonal results from WHOI/MATCH
Nevison (in progress)
Fidelity of seasonal cycles
Nevison (in progress)
Fidelity of seasonal cycles
relative phasing
mod/obs
Nevison (in progress)
Fidelity of seasonal cycles
Nevison (in progress)
Fidelity of seasonal cycles
Palmer
Model skill depends on hemisphere
Nevison (in progress)
latitudinal gradients in WHOI/MATCH
WHOI/MATCH
WHOI/MATCH
Battle data
Gruber ’01/MATCH
Gruber/MATCH
Gruber/TM3
ATM uncertainties trump OBGCM fluxes again
Nevison (in progress)
Tohjima et al.
(Tellus B, submitted)
• Repeat carbon sink partitioning
• Look at APO variability
Atmosphere-ocean partition
Tohjima et al. (submitted)
Interannual variability in APO
~20 month smoothing
Tohjima et al. (submitted)
Variability reflects O2 fluxes; not carbon.
12 Pg C/yr? Of course not.
~20 month smoothing
Tohjima et al. (submitted)
Atmosphere-ocean partition
APO variability
Tohjima et al. (submitted)
Further evolution of the interpolar gradient
~2-year smoothing
•Spatial structure
of APO is
genuinely timedependent
~2-year smoothing
•Spatial structure
of APO is
genuinely timedependent
•Neighboring
stations move
independently
~2-year smoothing
•Spatial structure
of APO is
genuinely timedependent
•Neighboring
stations move
independently
•Watch out for
end-effects
~2-year smoothing
Hamme, Keeling & Paplawsky
(AGU, 2006)
•Interhemispheric temporal variability
•Mechanisms
Work of Hamme et al. will be available
upon publication (expected in late 2007)
Broad
conclusions:
•APO reflects (too) many oceanic
properties
•Dataset is good but not great
•Interpreting ocean models
complicated by atmospheric
transport
More detailed conclusions
•A model combo can get seasonality
right, but still miss annual averages
•Some indications that winter
ventilation plays a big role
•Apparent global signal of NAM
•May be an El Niño signal too
O2 and CO2 fluxes are related,
but not intimately.
The degree of linkage depends
on temporal and spatial scale.