Bermuda Bio-Optics Project

1
Bermuda Bio-Optics Project

• Decade-Plus Perspective on Ocean Color

Norm Nelson, Dave Siegel Institute for
Computational Earth System Science, UCSB
2
Bermuda Bio-Optics Project

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

3
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

4
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

5
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)

6
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

7
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)

8
Bermuda Bio-Optics ProjectRadiometry 14 year
time series
441 nm (MER)
441 nm (MER)
443 nm (SPMR)
9
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?

10
BATS CDOM Profile
STMW
Surface Bleached Layer
STMW (18 Water)
Main Thermocline
11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17

• CDOM exhibits seasonal and interannual
  variability
• Possible teleconnection to climate oscillators
  (NAO shown)

18
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)

19
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

20
Particle Absorption
21
(No Transcript)
22
(No Transcript)
23
(No Transcript)
24
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

25
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

26
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)