ROV Fiber Optic Coupled Spectrograph Preliminary Results

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ROV Fiber Optic Coupled Spectrograph Preliminary
Results

Dennis Clark withMark Yarbrough Mike
Feinholz Stephanie Flora Steve Brown Carol
Johnson
OCRT Science Team Meeting April 2005
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Insitu AOP Measurements Considerations for the
high absorption cases.

• Approximately 95 of the remotely sensed signal
  originates from the first optical depth.
• This 1/K depth ranges spectrally from 10s to
  tenths of meters.
• Coastal applications are impacted in both the
  short and long wavelength regions.
• Measurement Implications
• Requires the Lu measurements accurately
  characterize the near-surface optical
  environment.
• Spatial and Temporal Variability
• Difficulty increases as absorption increases
• Instrument self-shadowing
• Depth accuracy
• Spectral bandwidth

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Instrument Self-Shadowing-Turbid Case
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Measurement Depth Accuracy
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Lu Spectral Response
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Ac9Bay AC Time Series
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Fiber Optic ROV/MOS Components
Seabotix- ROV
Es
Lu lt 5mm
1meter
1mm Quartz Fiber
MOBY Spectrograph
0.2mm Quartz Fiber
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Fiber Optic Right Angle Collector
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Spectrograph Fiber Coupling
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MOBY Spectrograph Specifications
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ROV Specifications
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ROV Insitu
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Northern Chesapeake Bay- Aqua 06 October 2004 -
Hurricane Impact

• Sept. hurricanes
• Francis, Ivan Jeanne
• Highest recorded (1937) freshwater discharge
• Ivan - 10M tons of sediment into Bay 3x annual
  average.
• Average daily freshwater flow 430 above normal
  for the month of Sept.

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Hyperion - Chesapeake Bay Oct. 4 6 2004
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NURADS Upwelling Radiance Distribution, 410 nm
Towards Sun
Nadir
Away From Sun
Turbid Water, Chesapeake
Clear Water (Hawaii)

• Radiance distribution more symmetric around Nadir
  in Turbid Water. Note minimum is towards sun
  direction in clear water.
• Radiance distribution varies more from nadir
  towards horizon in turbid water
• (factor gt4 vs 1.3 in above example).

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Surface Incident IrradianceMajor Fraunhofer and
Absorption Lines
H2O
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Chesapeake Bay - Lu - stn. 06
Chlorophyll a - 10 mg m-3
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Chesapeake Bay - Lw - stn. 06
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Chesapeake Bay - Lu - stn. 26
Chlorophyll a - 93 mg m-3
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Chesapeake Bay - Lw - stn. 26
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Hawaii - Lu Es
Chlorophyll a - 0.11 mg m-3
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Hawaii - RSG Lu
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Hawaii - Lw Depth Difference
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Hawaii Chesapeake Kls
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Hawaii Chesapeake Bay Lw Ratios
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Hawaii - Trichodesmium Bloom
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Kaneohe Bay Coral Reefs - Spectral
DiversityNight Ops. - Blue Light
ExcitationGreen Fluorescent Proteins Algae
680 nm Fluorescent
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Kaneohe Bay - Corals
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Some Recommendations

• Focus on a few well design experiments with
  appropriate instrumentation.
• Move to high spectral resolution (1-2 nm)
  radiometry.
• Fiber optic collection systems.
• Longer wavelengths promising for coastal
  bio-optical product derivation. NIR critical for
  coastal atmospheric correction.
• Understand and state the implications of
  systematic measurement biases e.g. spectral
  responses, path lengths, spatial and temporal
  variability.
• Climate Quality Data - Remote Insitu
• Characterize, Characterize, Characterize, ..
• Calibrate, Calibrate, .
• Keep Ocean Color - Snake Oil Free! Focus on the
  Basics!