OASIS 2006 meeting, February 2 nd , WHOI

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OASIS 2006 meeting, February 2 nd , WHOI. MISC lab report Emmanuel Boss & Wayne Slade. Processed data (available on our FTP site) includes O(12days) of 1min averages of: C-side ac-9. LISST-FLOC. LISST-B. BBRT ( b (117)) Nortek ADV (3D velocity. Acoustic backscattering).
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OASIS 2006 meeting, February 2nd, WHOIMISC lab reportEmmanuel Boss & Wayne Slade
  • Processed data (available on our FTP site) includes O(12days) of 1min averages of:
  • C-side ac-9.
  • LISST-FLOC.
  • LISST-B.
  • BBRT (b(117))
  • Nortek ADV (3D velocity. Acoustic backscattering).
  • Signs of biofouling are evident in LISST’s data towards the end of the deployment.Ac-9 data:Cp:Trend towards smaller gSuggests filtration system worked well for 12 days.Large and rapid changes in beam attenuation.Ac-9 data:Cp:Change of relationship in time (disaggregation ?).Ac-9 data:Colored dissolved organic material:
  • Suggests filtration system worked well for 12 days.
  • 676nm absorption increases as function of time (Organic coating of windows/ instrumental drift). Removal of red signal removes much of the increase.
  • Influence of particulate resuspension events is not observed.
  • Combine LISST-B and Floc data:LISST-F3 random 1min averages samplesBlack-flocRed-BPetzold,LISST-BAc-9Matching LISST-FLOC and LISST-B to obtain the phase function (and ultimately the VSF) in the near forward.How do the beam attenuation’s compare?LISST-B&FLOC data:Order of beam-c is consistent with acceptance angles (0.02, 0.1, 0.7).High frequency changes in beam attenuation (changes 2-7 fold in < 6 hrs).Drift in LISST relative to ac-9 (t>12) and relative to each other (t>15).Ac-9, LISST-B&FLOC data:Trend towards higher R
  • Ratio to cLISST-B varies from 0.35 to 1.0 (Rmedian=0.63, to LISST-F Rmedian=0.57).
  • Petzold: between 1535% of scattering is between 0.10.8.
  • Diver visibility ~ 4/c. Which c?
  • ADV-backscattering, BBRT and cp,ac-9:
  • bbp/cp ~0.025 throughout.
  • Acoustic scattering behave differently.
  • Interesting puzzles:
  • Size distribution changes as turbidity increase are towards:
  • Larger particles based on cp spectrum inversion.
  • Smaller particles, based on LISST inversion & ratio of cac9/cLISST
  • DSingle grainMicro flocMacro flocPossible explanation: Resuspended single-grain particles are larger as bottom stress increases. Macro floc break at higher shears becoming smaller.Particulate properties cycle is ~12hr. If shear due to tidal current dominated the stress cycle would be ~6hr. Possible explanation: cycle is driven by interaction of directional waves with the tides.Still to process:ABS (AQUAScat)Sontek ADVBB-9A-side ac9
  • Issues to discuss:
  • Calibration of acoustics devices.
  • Depth resolution of optical properties in future deployments.
  • Papers:Submitted: Optics Express: Calibrating the LISST to obtain VSF.Synthesis:Particle dynamics –floculation, setling and breakup.
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