Glider observations of thermohaline staircases in the tropical North Atlantic using an automated classifier

Rollo, Callum, Heywood, Karen J. ORCID: and Hall, Rob A. ORCID: (2021) Glider observations of thermohaline staircases in the tropical North Atlantic using an automated classifier.

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Thermohaline staircases are stepped structures of alternating thick mixed layers and thin high gradient interfaces. These structures can be up to several tens of metres thick and are associated with double-diffusive mixing. Thermohaline staircases occur across broad swathes of the Arctic and tropical/subtropical oceans and can increase rates of diapycnal mixing by up to five times the background rate, driving substantial nutrient fluxes to the upper ocean. In this study, we present an improved classification algorithm to detect thermohaline staircases in ocean glider profiles. We use a dataset of 1162 glider profiles from the tropical North Atlantic collected in early 2020 at the edge of a known thermohaline staircase region. The algorithm identifies thermohaline staircases in 97.7 % of profiles that extend deeper than 300 m. We validate our algorithm against previous results obtained from algorithmic classification of Argo float profiles. Using fine resolution temperature data from a fast-response thermistor on one of the gliders, we explore the effect of varying vertical bin sizes on detected thermohaline staircases. Our algorithm builds on previous work with improved flexibility and the ability to classify staircases from profiles with poor salinity data. Using our results, we propose that the incidence of thermohaline staircases is limited by strong background vertical gradients in conservative temperature and absolute salinity.

Item Type: Article
Additional Information: Funding information: CR was supported by the Natural Environment Research Council and the Engineering and Physical Sciences Research Council, via the NEXUSS Centre of Doctoral Training in the Smart and Autonomous Observation of the Environment Grant NE/N012070/1. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (COMPASS, Grant agreement No. 741120).
Faculty \ School: Faculty of Science > School of Environmental Sciences
University of East Anglia Research Groups/Centres > Theme - ClimateUEA
UEA Research Groups: Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Faculty of Science > Research Groups > Collaborative Centre for Sustainable Use of the Seas
Depositing User: LivePure Connector
Date Deposited: 23 Mar 2022 15:30
Last Modified: 24 May 2023 05:39
DOI: 10.5194/gi-2021-27


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