The Open UniversitySkip to content

Mixing and convection in the Greenland Sea from a tracer-release experiment

Watson, A. J.; Messias, M-J.; Fogelqvist, E.; Van Scoy, K. A.; Johannesen, T.; Oliver, K. I. C.; Stevens, D. P.; Rey, F.; Tanhua, T.; Olsson, K. A.; Carse, F.; Simonsen, K.; Ledwell, J. R.; Jansen, E.; Cooper, D. J.; Kruepke, J. A. and Guilyardi, E. (1999). Mixing and convection in the Greenland Sea from a tracer-release experiment. Nature, 401(6756) pp. 902–904.

DOI (Digital Object Identifier) Link:
Google Scholar: Look up in Google Scholar


Convective vertical mixing in restricted areas of the subpolar oceans, such as the Greenland Sea, is thought to be the process responsible for forming much of the dense water of the ocean interior. Deep-water formation varies substantially on annual and decadal timescales, and responds to regional climate signals such as the North Atlantic Oscillation; its variations may therefore give early warning of changes in the thermohaline circulation that may accompany climate change. Here we report direct measurements of vertical mixing, by convection and by turbulence, from a sulphur hexafluoride tracer-release experiment in the central Greenland Sea gyre. In summer, we found rapid turbulent vertical mixing of about 1.1 cm^2 s^-1. In the following late winter, part of the water column was mixed more vigorously by convection, indicated by the rising and vertical redistribution of the tracer patch in the centre of the gyre. At the same time, mixing outside the gyre centre was only slightly greater than in summer. The results suggest that about 10% of the water in the gyre centre was vertically transported in convective plumes, which reached from the surface to, at their deepest, 1,200–1,400 m. Convection was limited to a very restricted area, however, and smaller volumes of water were transported to depth than previously estimated. Our results imply that it may be the rapid year-round turbulent mixing, rather than convection, that dominates vertical mixing in the region as a whole.

Item Type: Journal Article
ISSN: 1476-4687
Academic Unit/Department: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Environment, Earth and Ecosystem Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 9120
Depositing User: Kevin Oliver
Date Deposited: 04 Feb 2009 06:48
Last Modified: 04 Oct 2016 10:05
Share this page:


Scopus Citations

▼ Automated document suggestions from open access sources

Actions (login may be required)

Policies | Disclaimer

© The Open University   + 44 (0)870 333 4340