The University of Southampton
University of Southampton Institutional Repository

A Lagrangian SF6 tracer study of an anticyclonic eddy in the North Atlantic: patch evolution, vertical mixing and nutrient supply to the mixed layer

Law, C.S., Martin, A.P., Liddicoat, M.I., Watson, A.J., Richards, K.J. and Woodward, E.M.S. (2001) A Lagrangian SF6 tracer study of an anticyclonic eddy in the North Atlantic: patch evolution, vertical mixing and nutrient supply to the mixed layer Deep Sea Research Part II: Topical Studies in Oceanography, 48, (4-5), pp. 705-724. (doi:10.1016/S0967-0645(00)00112-0).

Record type: Article

Abstract

Biological and biogeochemical change in the surface mixed layer of an anticyclonic eddy at 60°N in the North Atlantic were monitored within a Lagrangian time-series study using the tracer sulphur hexafluoride (SF6). Four ARGOS buoys initially released at the patch centre remained closely associated with the SF6 patch over a 10-day period, with the near-circular eddy streamlines contributing to the stability and coherence of the patch. Progressive deepening of the surface mixed layer was temporarily interrupted by a storm, which increased mixed-layer nitrate and accelerated the transfer of SF6 to the atmosphere. Diapycnal exchange of SF6 was relatively rapid due to the shallow pycnocline gradient, and a vertical eddy diffusivity (Kz) of 1.95 cm2 s?1 at the base of the mixed layer was estimated from vertical SF6 profiles at the patch centre. Application of Kz to the nutrient gradients inferred vertical nitrate and phosphate fluxes of 1.8 and 1.25 mmol m?2 d?1, respectively, for the pre-storm period, which accounted for 33% and 20% of the reported in vivo uptake rates. Integration of the vertical nitrate flux and decline in surface layer nitrate suggest a total loss of 0.54 mmol N m?3 d?1 during the 5-day pre-storm period, of which in vivo nitrate consumption only accounted for 49%. Vertical transport of ammonium regenerated in the pycnocline accounted for up to 25% of in vivo phytoplankton uptake. The results suggest that the contribution of vertical turbulence to the mixed-layer nutrient pool was less important than that recorded in other regions of the open ocean, inferring that advective processes are more significant in an eddy. This study also emphasises the potential of SF6 for oceanic Lagrangian time series studies, particularly in dynamic regions, and in constraining estimates of new production.

Full text not available from this repository.

More information

Published date: 2001
Keywords: LAGRANGIAN METHODS, TRACERS, OCEAN EDDIES, VERTICAL MIXING, MIXED LAYER, ARGOS, DATA BUOYS, DIAPYCNAL MIXING

Identifiers

Local EPrints ID: 7933
URI: http://eprints.soton.ac.uk/id/eprint/7933
ISSN: 0967-0645
PURE UUID: 74d2057e-8bed-40c0-aab5-2847dfe26a24

Catalogue record

Date deposited: 10 Aug 2004
Last modified: 17 Jul 2017 17:13

Export record

Altmetrics

Contributors

Author: C.S. Law
Author: A.P. Martin
Author: M.I. Liddicoat
Author: A.J. Watson
Author: K.J. Richards
Author: E.M.S. Woodward

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×