Coastal CO2 fluxes from satellite ocean color, SST and winds

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Coastal CO2 fluxes from satellite ocean color,
SST and winds

• Pete StruttonCIOSS / College of Oceanic and
  Atmospheric Sciences
• Oregon State University
• 1. The coastal ocean as a CO2 sink (?)
• 2. Magnitude and variability of fluxes
• 3. Quantifying fluxes via satellite
• ? GOES-R Risk Reduction

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Coastal CO2 Fluxes

• pCO2 in the coastal environment (and the
  equatorial regions for that matter) is associated
  with characteristic chlorophyll and SST
  signatures.
• Using techniques such as multiple linear
  regression, it should be possible to determine
  sea surface pCO2 from space.
• Combining this with winds from either
  scatterometer(s) or coastal/buoy meteorological
  stations will facilitate flux calculations.
• Important In many areas we dont even know the
  sign of the flux.
• Coastal ocean important for quantifying
  terrestrial fluxes.

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NO3
NO3 gradient
Turbulent eddy-diffusion
NO3 flux
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Characteristics of the Oregon upwelling system

• What are the important properties that make this
  region a CO2 sink?
• Strong (but episodic) upwelling throughout
  summer.
• Extremely rapid depletion of NO3 and CO2.
• NO3 depleted from 34 ?M to essentially zero over
  10km
• Corresponding drawdown of CO2 from 600 to 200ppm
• Low concentrations offshore persist, despite
  variability nearshore
• Mean along-transect CO2 concentration typically
  300ppm
• Implies ?CO2 70ppm (as much as 150ppm on some
  transects)
• Minimal warming of the upwelled waters (cf
  California?)

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What is the magnitude of the sink?

• Assume the conditions off Oregon are
  characteristic of upwelling regions along the
  entire west coast.
• Assume an upwelling season from May to August.
• Carbon sink is 0.02 Pg C, approx. 5 of the
  annual mean North Pacific sink.
• or ½ of the North Pacific sink for the same time
  period (ie May to August).

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Coastal CO2 Relationship to temperature and
chlorophyll
N limitation offshore
Productivity CO2 uptake
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Coastal CO2 Fluxes Satellite requirements

• Chlorophyll and SST will enable significant
  progress via multiple linear regression
  techniques.
• Temporal resolution 3 hours will enable
  (primitive) budgets to be calculated tracking of
  processes such as productivity and subduction.
  Higher temporal resolution of course better.
• This is a dynamic environment any ability to
  clear or alias clouds will enhance badly-needed
  coverage.
• Critical spatial scales 1 to 10km.
• Current and proposed observational programs will
  provide the necessary in situ data for validation.

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Characteristics of the California upwelling system

• In contrast to Oregon, not a strong source or
  sink.
• Possible reasons (ie differences from Oregon)
• Limitation of CO2 drawdown by something other
  than NO3
• Greater warming (works against biological uptake)
• Evidence for a significant change, towards a
  source, circa 1998
• Illustrates the level of (lack of) understanding
  of the spatial and temporal variability.

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Coastal CO2 Relationship to physics and biology
N limitation offshore
Productivity CO2 uptake
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Coastal CO2 Relationship to temperature and
particulate carbon