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The vertical structure of upper ocean variability at the Porcupine Abyssal Plain during 2012-2013

Damerell, Gillian M. and Heywood, Karen J. and Thompson, Andrew F. and Binetti, Umberto and Kaiser, Jan (2016) The vertical structure of upper ocean variability at the Porcupine Abyssal Plain during 2012-2013. Journal of Geophysical Research. Oceans, 121 (5). pp. 3075-3089. ISSN 2169-9275.

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This study presents the characterization of variability in temperature, salinity and oxygen concentration, including the vertical structure of the variability, in the upper 1000 m of the ocean over a full year in the northeast Atlantic. Continuously profiling ocean gliders with vertical resolution between 0.5 and 1 m provide more information on temporal variability throughout the water column than time series from moorings with sensors at a limited number of fixed depths. The heat, salt and dissolved oxygen content are quantified at each depth. While the near surface heat content is consistent with the net surface heat flux, heat content of the deeper layers is driven by gyre-scale water mass changes. Below ∼150m, heat and salt content display intraseasonal variability which has not been resolved by previous studies. A mode-1 baroclinic internal tide is detected as a peak in the power spectra of water mass properties. The depth of minimum variability is at ∼415m for both temperature and salinity, but this is a depth of high variability for oxygen concentration. The deep variability is dominated by the intermittent appearance of Mediterranean Water, which shows evidence of filamentation. Susceptibility to salt fingering occurs throughout much of the water column for much of the year. Between about 700–900 m, the water column is susceptible to diffusive layering, particularly when Mediterranean Water is present. This unique ability to resolve both high vertical and temporal variability highlights the importance of intraseasonal variability in upper ocean heat and salt content, variations that may be aliased by traditional observing techniques.

Item Type:Article
Related URLs:
URLURL TypeDescription ItemBritish Oceanographic Data Centre ItemEuropean Centre for Medium-Range Weather Forecasts ItemNational Weather Service Climate Prediction Center ItemAquarius sea surface salinity mission ItemRAPID-WATCH MOC monitoring project
Heywood, Karen J.0000-0001-9859-0026
Thompson, Andrew F.0000-0003-0322-4811
Additional Information:© 2016. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Received 2 NOV 2015. Accepted 10 APR 2016. Accepted article online 13 APR 2016. Published online 13 MAY 2016. We would like to thank the scientists, technicians, officers and crew of the RRS Discovery cruise D381, the RV Celtic Explorer cruise CE13001, and the RRS James Cook cruises JC085, JC087 and JC090, especially those which were not primarily OSMOSIS cruises and so went out of their way to accommodate our glider deployments. We would also like to thank, in particular, the many people involved in CTD data collection, processing, water mass sampling and calibration, without which the glider data would be uncalibrated. The data presented in this study are the result of five research cruises and a full year of glider piloting and involved many contributions not represented in the author list. This work was supported by NERC grants NE/I019905/1, NE/I020083/1, and NSF award OCE 1155676. Additional funding was provided by the EU Framework 7 project EuroBASIN (FP7-ENV-2010). We also thank Noel Pelland and an anonymous reviewer for insightful comments that improved the paper. Data are held at the British Oceanographic Data Centre ( The ERA-Interim data were obtained from the European Centre for Medium-Range Weather Forecasts (downloaded from on 17 June 2014). The NAO index data were obtained from the National Weather Service Climate Prediction Center (downloaded from on 2 October 2014). The Aquarius sea surface salinity mission is a joint effort between NASA and the Argentinian Space Agency, CONAE (Comisin Nacional de Actividades Espaciales), data downloaded from on 19 June 2014. Data from the RAPID-WATCH MOC monitoring project are funded by the Natural Environment Research Council and are freely available from (data downloaded 11 September 2015).
Funding AgencyGrant Number
Natural Environment Research Council (NERC)NE/I019905/1
Natural Environment Research Council (NERC)NE/I020083/1
European Union FP7EuroBASIN (FP7-ENV-2010)
Subject Keywords:intraseasonal variability; North Atlantic; ocean gliders
Issue or Number:5
Record Number:CaltechAUTHORS:20161014-101531378
Persistent URL:
Official Citation:Damerell, G. M., K. J. Heywood, A. F. Thompson, U. Binetti, and J. Kaiser (2016), The vertical structure of upper ocean variability at the Porcupine Abyssal Plain during 2012–2013, J. Geophys. Res. Oceans, 121, 3075–3089, doi:10.1002/2015JC011423.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:71098
Deposited By: George Porter
Deposited On:14 Oct 2016 20:34
Last Modified:09 Mar 2020 13:18

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