Feb 2, 2017 - Prince of. Wales. Gulf of Alaska - Results. Stations where LISST & UVP were deployed .... National Science Foundation OCE ... Charitable Trust.
Marine particles in the Gulf of Alaska shelf system: spatial patterns and size distributions from in situ optics Turner, J.T., Pretty, J.L., and McDonnell, A.M.P. Jessie Turner M.S. University of Alaska Fairbanks VIMS Ph.D. Student Physical Sciences Seminar February 2, 2017
Outline • • • • • • • •
Introduction Objectives and Hypotheses Methods Testing the UVP Results from the Gulf of Alaska (UVP and LISST) Discussion Implications Conclusions
Introduction
Introduction
(Hannes Grobe 2006)
Introduction The Biological Pump
Introduction
(Herndl & Reinthaler 2013)
Introduction Smaller-scale particle dynamics
Introduction
(Burd & Jackson 2009)
Introduction Sinking: Fluxes
(Buesseler et al. 2009)
Suspended: Concentrations
(Pollard 2008)
(A. Babbin)
(A. MacDonald) (Bishop et al. 2012)
Introduction Optical Instruments
(A. McDonnell) (A. Mishonov)
Introduction
(Turner Designs)
(Fluid Imaging Technologies)
(Herman 2004)
Introduction Imaging Systems SIPPER
ZOOVIS
(M. Sutor) Introduction
(A. Remsen)
VPR
ISIIS
(R.Cowen)
(C. Davis)
Introduction The Underwater Vision Profiler (UVP)
Introduction
Introduction Past work with the UVP
(Forest et al. 2012)
(Roullier et al. 2014)
(Guidi et al. 2012)
Introduction
(Stemmann et al. 2008)
Jouandet et al. 2014
(Guidi et al. 2008, 2009)
Introduction The Gulf of Alaska
(Stabeno et al.
Introduction The Gulf of Alaska
Introduction
(C. Ladd)
Introduction The Gulf of Alaska
Introduction
(NOAA Fisheries)
Introduction The Gulf of Alaska
Introduction
(NOAA, August 2000)
Objectives 1. Improve our knowledge of the UVP as a method for measuring particle concentration and size 2. Assess the spatial variability in particle concentrations and size distributions in the Gulf of Alaska
Hypotheses H1. UVP particle concentrations will be comparable with chlorophyll a concentrations H2. Particle concentrations and size distributions will be driven by biological processes in the Gulf of Alaska
Methods
Chapter 1: UVP
Methods Concentration Size Distributions
𝐸= 𝑛
Chapter 1: UVP
Methods Poisson distribution counting statistics
𝐸= 𝑛
Count:
25 +/- 5 1 Liter of water
4 +/- 2
Methods Descent rate = 1 m/s
Descent rate < 0.3 m/s 2.7 cm interval
3.5 cm
9 cm interval
Chapter 1: UVP
Methods Selecting the downcast
Chapter 1: UVP
Methods Removing Glow
Instrument-specific constants
Am=0.0032*Ap 1.36 Area in mm
Area in pixels
Equivalent Spherical Diameter ESD = 2 𝐴𝑚/𝜋 Chapter 1: UVP
Methods Depth Bins
𝐸= 𝑛
Chapter 1: UVP
1-m
5-m
15m
Methods Merging Size Distributions
UVP #/L µL/L using median diameter of each size bin LISST
UVP
Methods Merging Size Distributions LISST data >100 µm was removed – known limitation of LISST instruments for large particles
LISST
UVP
Methods Merging Size Distributions 3 overlapping size bins were averaged
LISST
UVP
Methods Merging Size Distributions
LISST
UVP
Methods Merging Size Distributions
LISST
UVP
Methods Objects >500 µm
Chapter 1: UVP
Methods Objects >500 µm
Chapter 1: UVP
Testing the UVP
Chapter 1: UVP
Testing the UVP
Chapter 1: UVP
Testing the UVP Methods used alongside UVP May 2014 CTD rosette-mounted: - Fluorometer - Transmissometer J. Questel
Chapter 1: UVP
Size-Fractionated Chlorophyll a
Testing the UVP UVP vs. in situ chlorophyll a fluorescence
Chapter 1: UVP
Testing the UVP UVP vs. in situ chlorophyll a fluorescence p = 0.985
Chapter 1: UVP
Testing the UVP UVP vs. Transmissometer Beam-c
Chapter 1: UVP
Testing the UVP UVP vs. Transmissometer Beam-c p = 0.0616
Chapter 1: UVP
Testing the UVP UVP vs. Size-fractionated Chlorophyll a fluorescence
Chapter 1: UVP
Testing the UVP UVP vs. Size-fractionated Chlorophyll a fluorescence p = 0.00627
Chapter 1: UVP
p = 0.283
Testing the UVP UVP Particle Concentration NOT correlated with: • in situ chlorophyll a • in situ beam attenuation • size-fractionated chlorophyll a H1 Invalidated Chapter 1: UVP
Gulf of Alaska - Results
GOA-OA Cruise July-August 2015 UVP and LISST-deep Chapter 2: GOA
Gulf of Alaska - Results
Prince of Wales
Stations where LISST & UVP were deployed together
Gulf of Alaska - Results 1) Two maxima in particle concentration: Nearshore and Shelf Break (>1000µl/l) 2) Overall, large particles >100µm contributed most to volume concentrations 3) Anomalous size distribution slopes found where concentrations were high, for different reasons Chapter 2: GOA
Gulf of Alaska - Results
1) Two maxima in particle concentration: Nearshore and Shelf Break (>1000µl/l)
Gulf of Alaska - Results Western Cook Inlet
Hinchinbrook Entrance
Cross Sound Seward Line Shelf Break
1) Two maxima in particle concentration: Nearshore and Shelf Break (>1000µl/l)
Gulf of Alaska - Results
Gulf of Alaska - Results
Inputs from Shore
Gulf of Alaska - Results
Shelf break production
Gulf of Alaska - Results
Gulf of Alaska - Results
2) Overall, large particles >100µm contributed most to volume concentrations
Gulf of Alaska - Results
2) Overall, large particles >100µm contributed most to volume concentrations
Gulf of Alaska - Results
Copper River
Western Cook Inlet
Cross Sound Seward Line Shelf Break
3) Anomalous size distribution slopes found where concentrations were high, for different reasons
Gulf of Alaska - Results
Small size classes
Gulf of Alaska - Results • Mega-tidal Environment (11.4 m) • Waters exit inlet on west side
Small size classes
Gulf of Alaska - Results
Small size classes at the SURFACE
Gulf of Alaska - Results • Largest single river draining into the Gulf of Alaska • Fresh, low-density surface plume contains particles
Small size classes at the SURFACE
Gulf of Alaska - Results
Small size classes AND very large size classes
Gulf of Alaska - Results • Closer proximity to upwelling region • Phytoplankton and zooplankton
Small size classes AND very large size classes
Gulf of Alaska - Results
100-500 µm sizes
Gulf of Alaska - Results • Enhanced flocculation in channel draining many glaciers? • Limitations of UVP in turbid waters?
100-500 µm sizes
Gulf of Alaska - Results 1) Two maxima in particle concentration: Nearshore and Shelf Break (>1000µl/l) 2) Overall, large particles (>100µm) contributed most to volume concentrations 3) Anomalous size distribution slopes found where concentrations were high, for different reasons Chapter 2: GOA
Discussion • Nearshore, results did not support original hypotheses – most likely terrestrial drivers • Shelf break maximum in particle concentrations – most likely biological drivers Chapter 2: GOA
Discussion 1) Magnitude of sediment inputs from rivers and glaciers?
2) Scale of particle transport? 3) Large object images from UVP 4) Future directions Chapter 2: GOA
Discussion
1) Magnitude of sediment inputs from rivers and glaciers
Chapter 2: GOA
January 2014. NOAA Earth Observatory
Chapter 2: GOA
Copper River Watershed area 62,678 km2 Freshwater discharge of 56 km3/year 69% comes from glacial sources Sediment deposition rates >20 mm/year
The Gulf of Alaska
Background
“Line source” inputs – not well constrained
Discussion
Chapter 2: GOA
A. McDonnell
Discussion 2) Scale of particle transport
? (Ganti et al. 2014)
• • • •
62.5 µm particle Stokes’ Law settling rates Current velocity = 20 cm/sec Particle density = 2.2 g/cm3
Chapter 2: GOA
Height of resuspension (m)
Settling time (hr)
Advection length (km)
10
0.8
0.57
20
1.6
1.15
30
2.4
1.73
40
3.2
2.30
50
4.0
2.88
100
8.0
5.76
Discussion 2) Scale of particle transport
? (Ganti et al. 2014)
• • • •
62.5 µm particle Stokes’ Law settling rates Current velocity = 20 cm/sec Particle density = 2.2 g/cm3
Chapter 2: GOA
Height of resuspension (m)
Settling time (hr)
Advection length (km)
10
0.8
0.57
20
1.6
1.15
30
2.4
1.73
40
3.2
2.30
50
4.0
2.88
100
8.0
5.76
Discussion 3) Large object images At all stations: • Most large object images (>500 µm) were detrital aggregates • Zooplankton accounted for less than 5% of all large object images
Discussion 3) Large object images
At all stations: • Most large object images (>500 µm) were detrital aggregates • Zooplankton accounted for less than 5% of all large object images
5 mm
Discussion 3) Large object images Hinchinbrook Entrance
Chapter 2: GOA
Copper River
Cross Sound
Limitations of the UVP in high-turbidity waters?
Discussion 4) Future Directions – Particle Collection in Sediment Traps
Chapter 2: GOA
Discussion
4) Future Directions – Zooplankton identification and spatial distributions
Chapter 1: UVP
Conclusions
May 9, 2014 – During our UVP Test Chapter 2: GOA
NASA Ocean Color
Conclusions • The UVP maintains fine resolution while sampling large volumes of water • Physical drivers dominate particle dynamics nearshore while biological drivers influence the shelf break • Size distributions are heterogeneous and driven by local phenomena
Acknowledgments
• Graduate Advisory Committee Andrew McDonnell, Ana Aguilar-Islas, Mark Johnson • Marc Picheral and coworkers at Hydroptic, Inc. in Villefrance, France • Crew and Captain of the R/V Tiglax • Russ Hopcroft & Seward Line scientists • Crew and Captain of NOAA Vessel Ronald H. Brown • P16N Leg 2 CLIVAR scientists • Jess Pretty, Cheryl Hopcroft, Jonathon Whitefield • SFOS Graduate students
Funding Sources: • UAF School of Fisheries and Ocean Sciences • GK-12 Changing Alaska Science Education Fellowship • National Science Foundation OCE • Intrumentation: M.J. Murdock Charitable Trust • Seward Line Funding Sources: NPRB, AOOS, GulfWatch
Questions?
