Published July 15, 2022 | Version v1
Dataset Open

The effect of pseudofrazil particle entrainment on salinity measurements: Data

Authors/Creators

  • 1. Department of Physics, University of Otago, Dunedin, New Zealand
  • 2. National School of Surveying, University of Otago, Dunedin, New Zealand

Description

This experiment was designed to investigate the effect of entraining frazil ice particles found in supercooled ocean water by mimicking their effect through plastic particles of similar material properties as ice. 
This was done in order to better control the volume concentration of the particles and avoid damage to sensors by icing which is common in supercooled water.
In total six experiments were run in which non-spherical round polyamide-12 seeding particles made by Dantec Dynamics A/S with a mean diameter of 50 micro meters were added to natural saltwater tinged with surfactant whilst recording temperature and conductivity with Sea-Bird Electronics sensors. 
Surfactant was Ecostore-brand eucalyptus laundry liquid (ingredients can be found here: https://ecostore.com/au/eucalyptus-laundry-liquid-409/, last accessed July 2022).
Experiments are H1, H2 and HC performed with saltwater taken from Otago Harbour, Dunedin, New Zealand and M1, M2 and MC performed with saltwater taken from the Munida Transect offshore of Otago Peninsula, Dunedin, New Zealand.
HC and MC were run in a walk-in freezer with water temperatures around -1 degrees C, all other experiments were performed at ambient room temperatures.
The setup consisted of a 30 litre bucket containing 24 litres of seawater filtered to 1 micro meter. Surfactant was added to the water to aid particle dispersion. 
Subsequently particles were added in increments to a total mass of particles in the bucket of 100 g.
Temperature was recorded with a SBE3plus temperature sensor and conductivity with a SBE4C sensor. 
These were connected to a SBE pump with standard SBE CT ducting. 
Data were recorded with a SBE31 deck unit connected to a laptop computer.
Data were recorded continuously, times at which particles were added or other operations performed are given in the tables <experimentname>info.xlsx
Raw data were converted using the sensors' calibration coefficients and corrected for CT offset and cell thermal mass using the SBE data processing software and standard values for sensors configured as in the SBE911+ setup, which is equivalent to the ducting used by us.
A manuscript with results from these experiments is available as Richter, M. E., et al., 2023, The Effect of Pseudofrazil Particle Entrainment on Salinity Measurements, Earth and Space Science, doi:10.1029/2022EA002564

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Notes

Connected datasets and publications: Richter, M.E., Smith, I.J., Everts, J.R., Russel, P., Langhorne, P.J., Leonard, G.H. (2023). The Effect of Pseudofrazil Particle Entrainment on Salinity Measurements, Earth and Space Science, doi:10.1029/2022EA002564 Held, P., Kegler, P., Schrottke, K. (2014, aug). Influence of suspended particulate matter on salinity measurements. Continental Shelf Research, 85 , 1–8. doi: 10.1016/j.csr.2014.05.014 Held, P., Kegler, P., & Schrottke, K. (2022). Influence of suspended particulate matter on salinity measurements [dataset]. Zenodo. doi: 10.5281/ZENODO.6839772 Le Menn, M., Pacaud, L. (2017). Effect of Sediment Suspensions on Seawater, Salinity Assessments. Journal of Water Resources and Ocean Science, 6 (2),23. doi: 10.11648/j.wros.20170602.11 Le Menn, Marc, Pacaud, Laurent (2022). Effect of sediment suspensions on seawater conductivity measurements. doi: 10.5281/zenodo.6778681 Acknowledgements: Thanks to Kim Currie from NIWA (Otago) and Doug Mackie from the Portobello Marine Laboratory, Department of Marine Science, University of Otago, for the loan of filtering equipment and for advice on removing particles from water. Thanks to Evelyn Armstrong, Department of Chemistry, University of Otago, for use of her lab space. Thanks to John Marko and David Topham who kindly shared experiences from their own experiments with plastic particles in seawater and for valuable discussions on experiment design. Special thanks to Marc Le Menn and Philipp Held who very kindly made their results available for comparison. We are grateful to Nordeen "Norge" Larson for the information on historic experiments done at the APL, University of Washington and Sea-Bird Electronics on conductivity cell geometry and displacement of water volume by non-conducting particles. Lars Henrik Smedsrud provided useful advice on previous attempts to examine frazil impacts on conductivity. Advice from Kim Martini at Sea-Bird Electronics and Natalie Robinson at NIWA (Wellington) proved very useful when analysing the results. Matthew Parry from the Department of Mathematics and Statistics at the University of Otago provided valuable advice on statistics. Funding: This work is an output from the project "Supercooling measurements under ice shelves" supported by the Marsden Fund Council from government funding, administered by the Royal Society of New Zealand (PI: Inga Smith, contract number: MFP-UOO1825). MER was supported by a University of Otago Doctoral Scholarship and the 2019 Antarctica New Zealand Sir Robin Irvine Scholarship. The University of Otago Department of Physics 2015 Summer Research Scholarship scheme provided financial support for J.R.E.'s involvement in this research.

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Additional details

References

  • Held, P., Kegler, P., & Schrottke, K. (2014, aug). Influence of suspended particulate matter on salinity measurements. Continental Shelf Research, 85 , 1–8. doi: 10.1016/j.csr.2014.05.014
  • Le Menn, M., & Pacaud, L. (2017). Effect of Sediment Suspensions on Seawater, Salinity Assessments. Journal of Water Resources and Ocean Science, 6 (2),23. doi: 10.11648/j.wros.20170602.11
  • Le Menn, Marc, & Pacaud, Laurent (2022). Effect of sediment suspensions on seawater conductivity measurements. doi: 10.5281/zenodo.6778681