The effect of pseudofrazil particle entrainment on salinity measurements

Richter, Maren ORCID: https://orcid.org/0000-0002-3658-3880, Smith, Inga J., Everts, Jonathan R., Russell, Pete, Langhorne, Pat J. and Leonard, Greg H. (2023) The effect of pseudofrazil particle entrainment on salinity measurements. Earth and Space Science, 10 (1). ISSN 2333-5084

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Abstract

Salinity effects of particles entrained into conductivity cells have previously mainly been studied in the context of suspended sediment. Particles influencing conductivity cells can also be small ice crystals (frazil) that may form in supercooled water. The detection of supercooled water depends on accurate, high precision temperature, salinity and pressure measurements. As it is currently not possible to measure salinity in situ, the standard procedure is to measure conductance over a known volume and calculate salinity. Frazil ice entrained into a conductivity cell changes the volume of conductive fluid in the conductivity cell, thus changing the conductivity, salinity and supercooling measurements. We present results on the effect of entraining microplastic into a Sea-Bird Electronics conductivity cell to simulate the effect of frazil. We show that particle volumes comparable to frazil volumes observed in the ocean change the measured conductivity and led to changes in calculated supercooling between 0.3 and 10 mK, possibly up to the same order of magnitude as naturally observed supercooling in the ocean. Further, we demonstrate that where supercooling is present, natural frazil ice concentrations can have an appreciable effect on parameters calculated with both the Equation of State of Seawater 1980 and Thermodynamic Equation of Seawater 2010 equations of state of seawater. Thus, to ensure accurate measurements in locations of very high frazil concentration, the entrainment of frazil needs to be prevented, which is not possible with methods currently available, or corrected for. An example for such a correction is given and could be modified to be applicable to other particles, for example, sediment.

Item Type: Article
Uncontrolled Keywords: supercooling,frazil ice,conductivity measurements,particles in conductivity cells,ice-ocean interaction,salinity measurements in high latitudes,sdg 14 - life below water ,/dk/atira/pure/sustainabledevelopmentgoals/life_below_water
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: LivePure Connector
Date Deposited: 01 Oct 2024 11:30
Last Modified: 01 Oct 2024 11:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/96851
DOI: 10.1029/2022EA002564

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