OPA

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OPA PlankTOM5.0 - DMS

• Meike Vogt Corinne Le Quéré Erik T.
  Buitenhuis
• Sergio Vallina Laurent Bopp

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PlankTOM Series
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PlankTOM 5.0

• Physics OPA-ORCA (NEMO2)
• Resolution 2 deg, 31 depths
• 29 Tracers
• 3 Phytoplankton PFT Nanophytoplankton,
  Diatoms, Coccolithophorids
• 2 Zooplankton PFT Microzooplankton,
  Mesozooplankton

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Food Web PlankTOM5.0
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Ecosystem

• High latitudes Diatom dominated
• Coccolithophorids Dont grow south of 40 deg yet
• Nanophytoplankton Describe Rest, include
  Phaeocystis
• Microzooplankton Important around Equator and
  high latitudes
• Mesozooplankton High latitudes
• Generally No extreme chlorophyll values

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Chlorophyll - Seasonality

• No extreme concentrations
• Seasonality rather weak
• Concentrations in uM
• Low chlorophyll in the Southern Ocean
• Influence on DMS?

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DMS Module
sea-air flux
photolysis
DMS
T
Fe
DMSPp
free lyase
bacteria
grazing/exudation
PO4
DMSPd
grazing/exudation
mortality
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DMS Model

• 3 additional tracers DMSPp, DMSPd DMS
• DMSPp derived from biomass and cell quota (S/C
  ratio)
• S/C content varies with UV and nutrient stress
  (Sunda, 2000)
• S/C shows slight T dependence (cryohypothesis)
  (Stefels, 2007)
• Literature S/C values (Archer 2002)
• Diatoms S/C 0.002
• Nanophytoplankton S/C 0.01
• Coccolithophorids S/C 0.012
• Literature values minimal DMSPp/cell content,
  can vary up to 3-fold for all PFTs

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DMS Dynamics
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DMS Model SMS

• DMSPd production grazing by micro-/mesozooplank
  ton
• (74 available)
• mortality
• exudation/leakage
• DMSPd consumption bacterial consumption of
  DMSPd
• cleavage of DMSPd by free DMSP-lyase

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DMS Module SMS II

• DMS production grazing by micro-/mesozooplankto
  n (74 DMSPd available)
• mortality
• exudation/leakage
• cleavage of DMSPd by free DMSP-lyase
• bacterial consumption of DMSP
  (microbial yield 10)
• DMS degradation bacterial consumption of DMS
• photolysis at the sea surface
• sea-air flux

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Preliminary Results

• Results very low compared to Kettle
• Equatorial regions ok.
• But what is happening in the high
• latitudes?????????
• Lack of Phaeocystis may explain in
• parts
• High latitudes diatom dominated
• Poor DMS producers and grazed by
• large zooplankton

DMS Kettle nM
DMS PlankTOM nM
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Seasonality

• Low seasonality!
• High latitudes a mess
• But I am working on it!

MAM
DJF
SON
JJA
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DMS Chlorophyll

• Get decoupling for cell quota
• f(stress)
• Very little decouping without

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