Bermuda BioOptics Project

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Bermuda Bio-Optics Project

• Decade-Plus Perspective on Ocean Color

Norm Nelson, Dave Siegel Institute for Co
mputational Earth System Science, UCSB
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Bermuda Bio-Optics Project

• OverviewScience GoalsData StreamsAccomplishmen
  ts
  
• A Look at the Time Series

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Bermuda Bio-Optics ProjectOverview - Main
Science Goals

• Understand processes controlling underwater light
  environment in the Sargasso Sea
  
• Algorithm development(With Stéphane
  Maritorena)
  
• Calibration and validation of ocean color sensors

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Bermuda Bio-Optics ProjectOverview - Main
Science Achievements

• Light, primary productivity, and photosynthetic
  quantum yield
  
• Distribution and dynamics of CDOM(Sargasso Sea
  and global)
  
• Photochemistry and DMS cycling

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Bermuda Bio-Optics ProjectOverview - Data Streams

• Time-series co-located with BATS(32N 64W),
  starting in 1991Also - frequent regional
  studies
  
• Core MeasurementsEd, Es, Lu (7-14 l, BSI
  Satlantic radiometers)chl a (fluorometric)Sin
  ce 1994ap,ad (QFT)acdom (conventional UV-Vis
  spectroscopy)

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Bermuda Bio-Optics ProjectOverview - Data Streams

• Concurrent data from the BATS ProjectHydrography
  Carbon (inorganic, organic)NutrientsPrimary
  ProductionC and N flux (sediment
  traps)Phytoplankton pigments (HPLC)
• Other BBOP data (not full time-series)AC-9
  absorption coefficient profilesLw(0), ASD
  FieldSpec radiometerLsun, Microtops sunphotometer

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Bermuda Bio-Optics ProjectOverview - Data Streams

• Radiometer calibration in house, using
  NIST-traceable standards, participated in SeaWiFS
  and SIMBIOS intercomparisons Same engineer for
  entire project (Dave Menzies)

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Bermuda Bio-Optics ProjectRadiometry 14 year
time series
441 nm (MER)
441 nm (MER)
443 nm (SPMR)
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Bermuda Bio-Optics ProjectAbsorption Coefficient
10 Year Time Series

• Absorption Coefficient ComponentsCDOMPhytoplankt
  onDetritusPhytoplankton absorption ratios
  (440/674nm)
  
• Are there interannual or longer term trends in
  addition to already-documented seasonal patterns?

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BATS CDOM Profile
STMW
Surface Bleached Layer
STMW (18 Water)
Main Thermocline
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• CDOM exhibits seasonal and interannual
  variability
  
• Possible teleconnection to climate oscillators
  (NAO shown)
  

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Control of CDOM at BATS

• Annual Balance between local production and
  solar bleaching
  
• Interannual Multi-year accumulation at depth and
  resetting by deeper winter mixing (similar to
  DOC patterns)

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Absorption by Phytoplankton

• Phytoplankton pigments dominate absorption
  (detrital contribution small, correlated with
  phytoplankton)
  
• Strong seasonal cycle related to spring bloom
• Seasonal change in absorption properties related
  to photoadaptation and seasonal succession of
  phytoplankton species
  
• Primary production variability has been linked to
  climate oscillators such as ENSO

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Particle Absorption
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Trends in Absorbing Components at BATS

• CDOM abundance governed in part by physical
  processes possibly teleconnected to climate
  oscillators
  
• Phytoplankton abundance and species succession
  has not varied along the same time scales

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Conclusions (so far)

• The BBOP time series is enabling us to observe
  and diagnose ocean color variations occurring on
  climate-oscillator time scales.
  
• CDOM abundance apparently responds on these time
  scales
  
• So far we are not seeing this in a dramatic way
  with the phytoplankton community

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Acknowledgments

• Ocean Biology and Biogeochemistry Program, NASA
• Collaborators Ive not mentioned (there are many,
  thank you)
  
• BBOP and BATS Project technicians, engineers, and
  students over the years (I could fill several
  slides)