Emerging sensor technologies for linking optical, biogeochemical, biological and ecological properties Mike Twardowski

Transcription

1 Emerging sensor technologies for linking optical, biogeochemical, biological and ecological properties Mike Twardowski WET Labs, Inc. Narragansett, RI

2 Science Challenges What are the sources of backscattering? How can we get more than chl? Why do closure attempts usually fall short of expectations? At what temporal/spatial scales do optical properties need to be resolved in coastal/inland waters for algorithm development/validation?

3 Technical Challenges VSF measurements Polarized scattering Better characterization of optically relevant particles Better analytical models for particle scattering Better assessments of measurement biases and uncertainties Spatial and temporal sampling at relevant scales Measurements in very high turbidity

4 MASCOT: VSF (10:10:170 deg; 658 nm) ECOVSF: VSF (60 to 170 deg; multi- ) ECOBB3: VSF (124 deg; 470, 532, 650 nm) LISST: VSF (0.08 to 13 deg; 650 nm) AC9: absorption and attenuation (9 ) SBE49 CTD

5 VSF Measurement Considerations 5+ orders of magnitude variation in intensity from the near-forward to backward in single VSF several orders of magnitude natural dynamic range in intensity at any single angle rapid temporal variability in particle fields in surface waters rejecting ambient light is challenging at surface, particularly for low scattering signals in the backward calibration without absolute standard

6 Phase functions from Scripps Pier 1 background 2 mineral laden 3 bubble laden inversion Minerals 90 Bubbles min record Colloids Twardowski et al. 2012

7 Phase functions of randomly oriented asymmetric hexahedra (mineral-mimicking) Discrete Dipole Approx (DDA) and Improved Geometrical Optics Model (IGOM) monodispersions with radius 0.01 to 162 um, log spaced Twardowski et al. 2012

8 Bubbles from Inversion single bubble theory First time the theoretical bubble VSFs have been verified with in-situ measurements Currently the only method of resolving small bubbles in seawater Backscattering is higher with coating

9 Bubbles resolved with optics and acoustics large bubble size class from inversion 23 and 10 khz acoustic signal from bubbles sizes 143 and 332 m

10 Bubble concentration (/ml) Particle concentration (/ml) Bubble concentration (/ml) Bubbles in a Ship wake (Comparison among instruments) Acoustic resonator: Bubble size concentration [13 µm, 250 µm] HOLOSUB: Segmentation & Edge detection Particle concentration [8.5 µm, 250 µm] 11 (c) VSF inversion: Bubble concentration Log-normal population, Mode: 10 µm, S.D.: 1.1 µm Outline Instrumentation Deployment Modes Results I Results II Time (s) Twardowski, Talapatra, Czerski, Vagle

11 depth (m) (m) degree of linear polarization degree of linear polarization (-S12/S11) Polarized scattering measurements Santa Barbara Channel m binned data C ideal Rayleigh Sept, S12/S11 -S12 S11 angle 90 m particle max beta(theta) (m -1 sr -1 ) A angle B

12 S12/S11 Observed polarization during periods of bubble injection in the near-surface measurements Lorenz-Mie Theory angle

13 Multi-angle airborne polarimeter 62 m altitude 410 nm 550 nm Chowdhary et al. 2012

14 Closure assessments usually don t work For measurements: Absorption is typically largest source of uncertainty (scattering error and flow cell required) McKee-Piskozub making progress on scattering error Disruption of aggregates (e.g., Boss et al. 2009) Hyperspectral backscattering Are the assumptions used in modeling and measurements valid? Randomly oriented particles? Need better characterization of undisturbed optically relevant particles

15 Wa Modeled weighting functions for reflective tube absorption scattering error r=1.0 r=0.999 r=0.998 r=0.995 r=0.990 r=0.985 r=0.980 r=0.970 r=0.960 r= McKee and Piskozub, unpub Scattering Angle (deg)

16 Nonrandom particle distributions completely change our interpretation of radiative transfer, Adding shear to a culture of E coli increased backscattering 30% Marcos et al. 2011

17 In situ holographic microscope: HOLOCAM 3-D imaging of particles from <1 to 1000 µm size range in undisturbed, in-situ volumes WET Labs HOLOCAM JHU prototype

18 Malkiel et al. (2003) size and shape parameters of particles characterized in an undisturbed remote volume in every image orientation of all particles 3-D relative location of all particles particle tracking possibly some particle density characterization also SPM shear and turbulent dissipation rates

19 Simple bench top inline DHM 30 cm CCD camera spatial filter cuvette CW laser 20X objective CW laser good for quiescent solutions

20

21 A Free-Drifting Submersible Digital Holographic Imaging System (Holosub) PROTOTYPE TO HOLOCAM Joe Katz (Johns Hopkins University)

22 Depth (m) East Sound, WA, USA May, 2010 a b C particle concentration water density Dissipation rate (m 2 /s ) pulsed laser PIV PSD Small Particle Count (/ml) σ t (kg/m 3 ) Shear rate (/s) Talapatra et al., in review

23 Pseudonitzchia Chaetoceros socialis (~1 mm) 3.1 m 4.2 m preferential orientation! Eucampia 6.7 m 15.8 m Long diatom chains 6 ml sample volume

24 Depth (m) a Density (kg/m 3 ) b Dissipation rate (m 2 /s ) C Shear rate (/s) (I) (II) 8 Most of the water column shows statistically significant deviations from a randomly oriented particle field! 12 (III) Angle (Degrees) Diatom Mean chain Length (mm) Diatom chain count (/ml) Talapatra et al., in review

25 Next Generation Submersible Holocamera 1 m sample volumes: 10 L high mag 2.25 ml low mag

26

27 Concept for sampling effects of orientation

28 Polarization and orientation Pseudonitzschia

29 (x,y,z,dt) Sampling resolution: LOBO Land/Ocean Biogeochemical Observatory Small mooring system Hourly, real-time observations Maintenance cycle ~ 4 months Instrumentation Temperature, Conductivity, Pressure, Dissolved O2, Chlorophyll and phycobiliprotein pigment fluorescence, DOM fluorescence, Turbidity WET Labs SeaBird WQM Nitrate Satlantic SUNA sensor Phosphate WET Labs CYCLE sensor Ammonium WET Labs CYCLE sensor Wireless telemetry via cellular phone Emphasis on high quality, accuracy, and reliability

30 Depth (m) (x,y,dz,dt) Autonomous Moored Profiler (AMP) High resolution sampling of the full water column Maintenance cycle 1-2 months 150 meter capable Featured design for OOI Salinity The AMP design evolution represents over a decade of commitment.

31 Resolving phytoplankton dynamics with AMP Monterey Bay 2002 Monterey Bay 2005 decimal day (PDT) Sullivan et al. (2010) Cont. Shelf Res. 30: 50-65

32 Underlying Mechanisms physics behavior decimal day (PDT) non-motile diatoms highly motile dinoflagellates

33 (dx,dy,dz,dt) Mapping optical properties with a towed vehicle (DOLPHIN) Hudson River plume tow 1 tow 4

34

35 Thank you!