Biomes in satellite ocean color data

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Biomes in satellite ocean color data

• Mike Hiscock, Stephanie Henson
• Patrick Schultz, Eric Galbraith, John Dunne,
  Jorge Sarmiento

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Why try to divide the ocean into biomes?
Setting spatial bounds to ecosystems is an
essential step towards their quantitative study,
because The distribution of characteristic
marine ecosystems is predictable from a few
ecological principles, a simple understanding of
regional oceanography and an elementary knowledge
of the oceans geographical features, so we want
to know The area within which each
characteristic ecosystem may be expected to
occur, i.e. the biomes Alan Longhurst,
Ecological Geography of the Sea
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Longhursts provinces
Devised on the basis of physical characteristics
and PP
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Jorge et al.s biomes
Based on max MLD, sign of vertical velocity, ice
cover Sarmiento et al. (2004), GBC
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Oliver et al.s classification
Based on SST and 2 SeaWiFS bands Oliver et al.
(2008), Ocean Sciences
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Regional regions
Sub-tropical South Atlantic, based on SST and
chl Gonzalez-Silvera et al. (2004), Cont Shelf Res
Choice of biomes depends on questions you want to
answer (and on what scales)
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Biomes based on clustering of SeaWiFS chl and
carbon
Mean SeaWiFS chl-a (log 98-04)
Standard deviationSeaWiFS carbon biomass (log
98-04)
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Biomes based on clustering of SeaWiFS chl and
carbon
K-means clustering on st.dev. of carbon and mean
chl
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What are the biomes characteristics?
Blue carbon Green chl
Climatological monthly means (98-04)
Dynamic regions strong seasonality, high chl,
high NPP Stable regions no/weak seasonality, low
chl, low NPP
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What physical processes set these characteristics?
Dynamic regions chl increases when MLD
shallows Stable regions chl increases when MLD
deepens
Correlation between SeaWiFS chl and TOPAZ MLD
Blue MLD Green chl-a
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What physical processes set these characteristics?
Dynamic regions Light seasonally limiting Stable
regions Light never limiting
Mean light limitation factor (Behrenfeld et al.,
2005)
Light not limiting
Light limitation factor dependent on incoming
radiation, attenuation coefficient and mixed
layer depth
Light limiting
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What physical processes set these characteristics?
Distance from nutrient source separates gyre from
equatorial/gyre edge regions
Ideal nutrient measure of the length of time
upwelled water has been in sun-lit waters -
indicates nutrient advection from source
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Summary part 1

• Biomes separate ocean into dynamic and stable
  regimes
• Dynamic regimes (high latitudes) are light
  limited and require stratification for increased
  chl
• Stable regions (gyres) are nutrient limited and
  require mixing for increased chl
• In low latitudes, distance from source of
  nutrients (either equatorial upwelling or gyre
  edge) determines chl

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In variable (high lat) regions, high productivity
a result of shut-down of system in winter, due to
light limitation In stable (low lat) regions, no
reset of the system (because no light lim),
results in nutrient limitation
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