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VSF Measurements and Inversion. Michael Twardowski Matt Slivkoff Jim Sullivan Scott Freeman WET Labs, Inc., Narragansett, RI mtwardo@wetlabs2.com. IOP package. MASCOT: VSF b (10:10:170 deg; 650 nm) ECOVSF: VSF b (100, 125, 150 deg; 650 nm)
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VSF Measurements and Inversion Michael Twardowski Matt Slivkoff Jim Sullivan Scott Freeman WET Labs, Inc., Narragansett, RI mtwardo@wetlabs2.com
IOP package MASCOT: VSF b(10:10:170 deg; 650 nm) ECOVSF: VSF b(100, 125, 150 deg; 650 nm) ECOBB3: VSF b(117 deg; 470, 532, 650 nm) LISST: VSF b(~0.8 to 13 deg; 650 nm) AC9: a and c (9l) SBE49 CTD
Typical sampling day, 9/8 thru 9/16: • ~2 h within 0600 to 1000 timeframe • - full casts with linear polarization suite • 1-2 h within 1200 to 1400 timeframe • surface time series concurrent with CTD • 1-3 h within 1600 to 2000 timeframe • full casts or surface time series with • bubble resonator • Typical sampling day, 9/17 thru 9/22: • ~1 h within 1200 to 1330 timeframe • - 30 m casts with linear polarization suite • ~1 h within 1600 to 1730 timeframe • full and 30 m casts with linear polarization suite
Data Summary • Over 150 casts and time series collected • Concurrent in-situ measurements of the VSF resolved from <0.1 deg to 170 deg • 20 Hz in-situ VSF measurements, including linearly polarized elements (S1 and S2) • Quasi-concurrent sensor background measurements for optimized accuracy in all VSFs
Upper 50 m Temperature
Upper 50 m Salinity
Upper 50 m sT (kg m-3)
Upper 50 m chl (mg m-3)
Upper 50 m cpg(650) (1/m)
SBC KM site: 9/10 SBC KM site: 9/9 SBC KM site: 9/14 40° 40° 20° 10° 40° 20° 20° 10° 10°
SBC KM site: 9/10 SBC KM site: 9/14 deep water particle max
-S12 S11 MASCOT: DOLP SBC KM site: 9/14
SBC KM site: 9/10 SBC KM site: 9/14
SBC KM site: 9/15 (~1700) bubbles
SBC KM site: 9/15 (~1700) bubbles
SBC KM site: 9/15 (~1700) Mie theory bubbles (no coating) 2um thru 20um bubbles
LISST VSF Progress • Performed Dark Current characterization measurements • Implemented dark current correction on all LISST measurements and zscats (“pure water” background) • Performed ambient light characterization measurements • Implemented empirical ambient light detection and correction scheme • Ad-hoc ambient light baffle deployments (~75% of data) • Determined more accurate LISST angles • Different from Agrawal 2005 or Slade and Boss 2006 • Calibrated LISST VSF measurements using beads and Mie theory • Currently investigating acceptance angles and weighting functions of LISST ring detectors
Cast on day 19.69, SEP 5 m bins
Cast on day 19.69, SEP 5 m bins
Shape of the VSF in the backward direction bbp = 2p cp(q)bp(q) Complete 1 m binned data from 5 cruises values from Boss and Pegau (2001) Sullivan and Twardowski (in prep)
Ebbing tide with surfzone gradually approaching sampling site… Scripps Pier surfzone time series
set 5: bubbles set 4: sediments Optics with Acoustics
“young” plume: sediments+bubbles wave set 3: sediments 2 VSFs of background particle populations measurement 43265 at 37.69 minutes measurement 43285 at 35.71 minutes measurement 9301 at 7.67 minutes measurement 9121 at 7.52 minutes Scripps Pier particle scattering budget
Current Focus with SBC Data • MASCOT: cross-validate bead cals within a few % • Developing apparatus to determine W(q) emprically • All VSF measurements: subtract cast-specific darks • ac9: subtract cast-specific CDOM absorption to derive particulate IOPs
Potential Manuscripts • Oceanic near-forward VSF measurements with a Sequoia LISST (Slivkoff et al) • VSFs for Selected Ocean Waters: Revisited (Twardowski et al) • Shape of oceanic VSFs in the backward direction (Sullivan and Twardowski) • Polarized oceanic VSFs (Twardowski et al) • Acoustical inversion to derive bubble size distributions <20 um (Czerski, et al) • Time and depth varying radiance distribution in the ocean and its relation to the IOPs (Lewis, Voss, Vandonnelin, Wei, Twardowski, et al.) • Resolving bubble size distributions with optics and acoustics -Oceanography (Twardowski, Vagle, Czerski, Farmer, et al) • Resolving bubble size distributions with optics and acoustics - JGR (Twardowski, Vagle, Czerski, Farmer, et al) • Particle scattering dynamics in the surfzone • Particle scattering budget for SBC, KM site • Novel high dynamic range radiance camera (Vandonnelin et al) • Temporal dynamics of the snell’s cone (Wei, Lewis, et al) • LISST paper: implications of near forward scattering on image quality and visibility (Chang et al)