Transcript Remote Sensing of Southern Ocean Air-Sea CO2

REMOTE SENSING OF
SOUTHERN OCEAN AIR-SEA
CO2 FLUXES
A.J. Vander Woude
Pete Strutton and Burke Hales
Global CO2 flux
Takahashi et al., DSR I, 2009: 4.5 million data points
Takahashi et al., DSR I, 2009: 3 million data points
Global CO2 data coverage
Southern Ocean & atmospheric CO2
Observations versus models
Gruber et al. 2009
Why this may be better than
observational methods?
In some places there are no observations:
pCO2 from co-varying parameters is a way forward
We can investigate smaller spatial scales:
Limited by the resolution of the satellite data (kilometers),
not
sparse observations (~102 to 103 km)
We can investigate seasonal and interannual variability:
Links to long term changes in forcing: Southern Ocean
winds
Steps to Create Predictive Satellite
Algorithms: West Coast Example
Remote Sensing Climatology
Monthly Data
Sea Surface Height (cm)
Chlorophyll a (mg/m3)
Wind speed (m/s)
OI Reynolds Sea Surface Temperature (°C)
Sea Surface Height:
AVISO Multimission 19992008
Chlorophyll:
SeaWiFS 1999-2002,
MODIS/Aqua + SeaWiFS
Merged 2003-2007,
MODIS/Aqua 2007-2008
Wind speed:
QuickSCAT 1999-2008
OI Reynolds SST:
AVHRR 1999-2002,
AVHRR+AMSR 2002-2008
Steps to Create
Predictive Satellite Algorithms
Probablistic Self-Organizing Maps
January
February
March
region number
There is some correspondence between SOM regions and the fronts
Spatial and temporal coherence of the fronts from month to month
Longhurst 1998
Overview of Predictive Satellite
Algorithms
Powell’s Optimization
A
Alkalinity and DIC from the McNeil climatologies
Optimizing: Alk, DIC, Ti,
Heating/Mixing term, Tcr
Chlorophyll term
Each has a constant,
longitude, latitude &
seasonal signal
pCO2 Results & Accuracy of
Regional Model
Summer
Predicted
Spring
Obo
Observed
Region 4
May and June
pCO2 (ppm)
Autumn
pCO2 (ppm)
Red is a source to the atmosphere
Winter
White is at atmospheric
Blue is a sink, into the ocean
pCO2 (ppm)
pCO2 (ppm)
Conclusions
and future work
Satellite algorithms offer a way to fill gaps and better
quantify spatial and temporal variability of CO2
Next:
-- Finishing the monthly algorithms, by region as well as
Seasonal and interannual variability and produce maps of
CO2 fluxes for the Southern Ocean
-- More rigorous comparison with climatologies and
models.
Thank you!
• NASA for funding for this project
• Maria Kavanaugh for her help with the PRSOM analysis
and Ricardo Letelier’s lab use of their PRSOM/HAC code
CDIAC in situ pCO2 Coverage
1.4 million data points in the Southern Ocean, south of 40° S
SO GasEx observations and satellite
predictions
SO GasEx observations and
McNeil predictions
SO GasEx observations and
Takahashi predictions
Southern Ocean & atmospheric CO2
Contemporary sink of:
.1 to .5 PgC/yr
(circulation models & atm and
oceanic inversion models)
.5 to .7 PgC/yr
(pCO2 measurements,
Takahashi et al. 2002)
.15 to .65 PgC/yr
(empirical estimated pCO2,
McNeil et al., 2007)
Gruber et al. 2009