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dc.contributor.authorMacDonald, Iain T.en_NZ
dc.contributor.authorMullarney, Julia C.en_NZ
dc.date.accessioned2015-07-08T02:14:18Z
dc.date.available2015en_NZ
dc.date.available2015-07-08T02:14:18Z
dc.date.issued2015en_NZ
dc.identifier.citationMacDonald, I. T., & Mullarney, J. C. (2015). A novel ‘FlocDrifter’ platform for observing flocculation and turbulence processes in a Lagrangian frame of reference. Journal of Atmospheric and Oceanic Technology, 32(3), 547–561. http://doi.org/10.1175/JTECH-D-14-00106.1en
dc.identifier.issn0739-0572en_NZ
dc.identifier.urihttps://hdl.handle.net/10289/9449
dc.description.abstractA novel drifter platform was used to measure the properties of aggregated particles called flocs—a key component of sediment transport in muddy environments. Also concurrently measured were turbulence, suspended sediment concentration (SSC), velocity, and salinity in both Lagrangian and Eulerian frames of reference. In Lagrangian mode the system performed well in a heavily sediment-laden river, providing measurements over a large spatial scale. The platform navigated itself through a complex geometry encompassing many bends and significant depth changes. Observed velocities relative to the drifter and salinities indicated that the drifter motion was almost Lagrangian with minimal slippage between the drifter and the water motion. The small amount of slippage that did occur was sufficient to ensure that the drifter oriented itself into the oncoming flow. High-quality in situ images of flocs were collected using a high-magnification floc camera (FlocCam). An automatic image analysis routine was developed to identify and characterize flocs within each FlocCam image, employing an artificial neural network (ANN) to ensure that only in-focus particles were included in the analyses. The results indicated that the FlocCam system had an upper working SSC limit of around 350–400 mg L⁻¹. The SSC estimates show that the drifters encountered considerable variability as they were advected downstream; however, concentrations predominantly remained under the image processing threshold of 350–400 mg L⁻¹. The system captured the evolution of floc characteristics over short spatial scales (hundreds of meters). The median floc size (d₅₀) was found to be positively correlated with SSC (r² = 0.5). A comparison between Eulerian and Lagrangian floc histories can then be used to evaluate the role of antecedent conditions within the flocculation process.
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.publisherAmerican Meteorological Societyen_NZ
dc.relation.urihttp://journals.ametsoc.org/doi/abs/10.1175/JTECH-D-14-00106.1en_NZ
dc.rights© Copyright 2015 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act September 2010 Page 2 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a web site or in a searchable database, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS Copyright Policy, available on the AMS Web site located at (http://www.ametsoc.org/) or from the AMS at 617-227-2425 or copyrights@ametsoc.org.
dc.titleA novel ‘FlocDrifter’ platform for observing flocculation and turbulence processes in a Lagrangian frame of referenceen_NZ
dc.typeJournal Article
dc.identifier.doi10.1175/JTECH-D-14-00106.1en_NZ
dc.relation.isPartOfJournal of Atmospheric and Oceanic Technologyen_NZ
pubs.begin-page547
pubs.elements-id117499
pubs.end-page561
pubs.issue3en_NZ
pubs.volume32en_NZ
dc.identifier.eissn1520-0426en_NZ


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