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Profiles

Mr Emlyn Davies

Associate Lecturer

Biography

Biography

I am now working as a research scientist at SINTEF, Norway. My email is: emlyn.john.davies@sintef.noResearch Scientist: "Marine Optics"Active research topics include:

  • Linking marine optics to particle properties in natural marine environments
  • Modelling optical scattering and absorption from marine particles
  • Development of holographic image processing routines
  • Inter-comparison of measurement techniques for marine particles
    		•


    PhD Thesis: "Scattering Properties of Suspended Particles"

    NERC Studentship in collaboration with The National Oceanography Centre and Sequoia Scientific Inc.

    Supervisors:
  • Dr Alex Nimmo Smith (Director of Studies, Plymouth)
  • Dr Alejandro J. Souza (POL)
  • Dr Yogesh Agrawal (Sequoia Scientific Inc.)
  • Professor David Huntley (Plymouth)

    • Aim:
    To investigate the optical scattering characteristics of marine particles, with a view to improving the determination of their size.

    Importance:
    Improving the determination of marine particle characteristics is important because suspended particles:

  • Affect light penetration through the water,
  • Play an important role in the carbon cycle
  • Influence sound propagation
  • Affect the distribution of pollutants
  • Affect sediment transport

    • It is therefore crucial to have an accurate measurement of suspended particle characteristics so that we can effectively monitor the marine environment

    Many instruments for measuring particles rely on optical and acoustic scattering from the particles, and use Mie Theory or an alternate algorithm, to infer a particle size and concentration. However, these predictions have a number of significant restrictions. For example, Mie Theory assumes that the particles are spherical and of a known composition, and tested alternate algorithms do not cover the full range of particle sizes or types found within the marine environment. Various imaging techniques have proved that particles vary greatly in their shape and composition (Figure 1). As a result, there is significant uncertainty in the response of light scattering instruments to this diverse range of particles.

    Figure 1: Examples of flocs recorded by digital holography. (Scale bar = 0.5 mm.)

    Key Findings:
  • There are notable differences between measurements of suspended particle size and concentration in natural waters. It is therefore important to carefully measure forward scattering at the same time as capturing images of the particles in order to examine the causes for the differences.


    • Emlyn J. Davies, W. Alex M. Nimmo-Smith, Yogesh C. Agrawal, and Alejandro J. Souza, (2011), "Scattering signatures of suspended particles: an integrated system for combining digital holography and laser diffraction," Opt. Express 19, 25488-25499.

  • Differences between size measurements obtained from optical scattering (laser diffraction) and those from imaging could be due to particle shape. These differences appear to be minimised when considering sub-dimensions of particle shape


    • George W. Graham, Emlyn J. Davies, W. Alex M. Nimmo-Smith, David G. Bowers, and Katherine M. Braithwaite, (2012), "Interpreting LISST-100X measurements of particles with complex shape using Digital In-line Holography", Journal of Geophysical Research - Oceans.

  • The LISST-100 inversion of optical scattering into a particle size distribution will alias large particles (greater than the measurement range) into multiple smaller particles

    • Emlyn J. Davies, W. Alex M. Nimmo-Smith, Yogesh C. Agrawal, and Alejandro J. Souza, (2012), "LISST-100 response to large particles", Marine Geology, 307-310.

  • Non-spherical particles scatter asymmetrically when settling in fixed orientations, creating complications when inverting scattering into a particle size distribution

    • Emlyn J. Davies, W. Alex M. Nimmo-Smith, Yogesh C. Agrawal, and Alejandro J. Souza, (2012), "Interpreting Forward Scattering from Complex Marine Particles", Ocean Optics, Glasgow, UK. (Extended abstract, oral presentation & poster)

    Qualifications

    2006-2009: BSc (Hons) Ocean Science, School of Earth, Ocean and Environmental Science, University of Plymouth. Dissertation title: "Dynamics of Suspended Particulate Matter in the Lower Tamar Estuary".

    Professional membership

  • Associate Member of the Institute of Physics
  • Member of the American Geophysical Union
  • Member of the Marine Physics Research Group

    • Teaching

    Teaching

    Teaching interests

    Marine Optics & Acoustics (EOE2307) - 2012/2013 (Module leader, Dr Sarah Bass):

    I teach the marine optics component of this module (term 2). It covers the theory of light and its application to underwater optics, including on-board practical exercises in the Tamar Estuary. To apply the theory of attenuation to the analysis of real optical data, students deploy a PRR (Profiling Reflectance Radiometer) and CTD, and present their findings in a scientific report.

    Scientific Outreach & Communication:

    The impact of scientific research is not limited to scientists and universities. I am keen to try and demonstrate science and show our exciting research to anyone who is interested, including the general public, school teachers and pupils. Have a look at some of the videos from a recent cruise in the Irish sea:


    and The Submicron Song!


    I am registered as a STEM ambassador, which is a program aimed at inspiring young people in Science, Technology, Engineering and Mathematics, during public events and visits to schools. Visit stemnet.org.uk for more information.



    Research

    Research

    Research interests

  • Scattering and absorption by marine particles
  • Validation of optical measurements
  • Measurement technology (see poster on underwater digital holography)
  • Characterisation of natural marine particles
  • Science communication and outreach

    • Other research

  • 2011-present: Contributions to NERC project: “Measurement of the abundance and optical significance of sub-micron sized particles in the ocean”, in collaboration with Plymouth, Bangor and Strathclyde Universities: marinephysics.org/submicron
  • Apr-Jun2011: Research assistant, Plymouth University:HigherEducation Innovation Fund (HEIF) project for development ofholographic reconstruction software (marinephysics.org/holoproc) and development of a fluorescence imaging system.

    • Grants & contracts

  • October 2012: Ocean Optics (TOS) student travel grant. $500.
  • February 2012: Ocean Sciences Meeting (Salt Lake City) student travel award. $500.
  • January 2012: Plymouth Marine Science Education Fund travel grant for the Ocean Optics Meeting 2012. £250.
  • April-June 2011: Higher Education Innovation Fund (HEIF) project for development of holographic reconstruction software and development of a fluorescence imaging system (in conjunction with Sequoia Scientific Inc.). £23,719 to Alex Nimmo Smith.

    • Publications

    Publications

    Journals

    Peer Reviewed Journal Articles:

    George W. Graham, Emlyn J. Davies, W. Alex M. Nimmo-Smith, David G. Bowers, and Katherine M. Braithwaite, (2012), "Interpreting LISST-100X measurements of particles with complex shape using Digital In-line Holography", Journal of Geophysical Research - Oceans.

    Emlyn J. Davies, W. Alex M. Nimmo-Smith, Yogesh C. Agrawal, and Alejandro J. Souza, (2012), “LISST-100 response to
    large particles”, Marine Geology, Available online 3 April 2012, ISSN 0025-3227.

    Emlyn J. Davies, W. Alex M. Nimmo-Smith, Yogesh C. Agrawal, and Alejandro J. Souza, (2011), "Scattering signatures of suspended particles: an integrated system for combining digital holography and laser diffraction," Opt. Express 19, 25488-25499.
    http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-19-25-25488

    Conference Papers

    Conference Abstracts:

    Emlyn J. Davies, W. Alex M. Nimmo-Smith, Yogesh C. Agrawal, and Alejandro J. Souza, (2012), "Evaluating the LISST-100 Response to Complex Marine Particles", Particles in Europe (PiE), Barcelona, Spain. (Extended abstract & oral presentation)


    Emlyn J. Davies, W. Alex M. Nimmo-Smith, Yogesh C. Agrawal, and Alejandro J. Souza, (2012), "Interpreting Forward Scattering from Complex Marine Particles", Ocean Optics, Glasgow, UK. (Extended abstract, oral presentation & poster)

    George W. Graham, W. Alex M. Nimmo-Smith, David McKee, David G. Bowers, Robert MacDonald, Emlyn J. Davies, (2012), "Inconsistencies Between Theoretical Particle Abundance and In-Situ Observations in the Sea", Ocean Optics, Glasgow, UK. (Oral presentation & poster given by George Graham)

    Emlyn J. Davies, W. Alex M. Nimmo-Smith, George W. Graham, (2012), "Sequoia's LISST-HOLO: Results from a bedframe deployment in the Menai Strait, Wales", Oceanology International, London, UK. (Demonstration & poster). Invited.

    Emlyn J. Davies, George W. Graham, W. Alex M. Nimmo-Smith, (2012), "Towards understanding particle size distributions derived from laser diffraction", AGU/ASLO/TOS Ocean Sciences Meeting, Salt Lake City, Utah, USA. (Oral presentation)

    Emlyn J. Davies, W. Alex M. Nimmo-Smith, Yogesh C. Agrawal, and Alejandro J. Souza, (2010), "An integrated System for testing laser diffraction", Particles in Europe (PiE), Villefranche-sur-Mer, France. (Extended abstract & oral presentation)

    Emlyn J. Davies, W. Alex M. Nimmo-Smith, Yogesh C. Agrawal, and Alejandro J. Souza, (2010), "Scattering signatures of suspended sediments", Challenger Conference for Marine Sciences, Southampton, UK. (Oral presentation)

    Other Publications

    Emlyn J. Davies and W. Alex M. Nimmo-Smith, (2010), “Dynamics of suspended particulate matter in the lower Tamar Estuary”, Plymouth Student Scientist, 3(2), 63-108.

    Personal

    Personal

    Conferences organised

    •  October 2012: LISST-HOLO Workshop, Particles in Europe (PiE) Meeting (assistance with organisation & delivery)

    •  December 2010: Plymouth University Marine Institute Conference (member of organising committee)