Water mass properties and fluxes in the Rockall Trough, 1975-1998
A time series of a standard hydrographic section in the northern Rockall Trough spanning 23 yr is examined for changes in water mass properties and transport levels. The Rockall Trough is situated west of the British Isles and separated from the Iceland Basin by the Hatton and Rockall Banks and from...
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ftnerc:oai:nora.nerc.ac.uk:108932 2023-05-15T16:49:07+02:00 Water mass properties and fluxes in the Rockall Trough, 1975-1998 Holliday, N.P. Pollard, R.T. Read, J.F. Leach, H. 2000 http://nora.nerc.ac.uk/id/eprint/108932/ https://doi.org/10.1016/S0967-0637(99)00109-0 unknown Holliday, N.P. orcid:0000-0002-9733-8002 Pollard, R.T.; Read, J.F.; Leach, H. 2000 Water mass properties and fluxes in the Rockall Trough, 1975-1998. Deep-Sea Research I, 47 (7). 1303-1332. https://doi.org/10.1016/S0967-0637(99)00109-0 <https://doi.org/10.1016/S0967-0637(99)00109-0> Publication - Article PeerReviewed 2000 ftnerc https://doi.org/10.1016/S0967-0637(99)00109-0 2023-02-04T19:33:49Z A time series of a standard hydrographic section in the northern Rockall Trough spanning 23 yr is examined for changes in water mass properties and transport levels. The Rockall Trough is situated west of the British Isles and separated from the Iceland Basin by the Hatton and Rockall Banks and from the Nordic Seas by the shallow (500 m) Wyville–Thompson ridge. It is one pathway by which warm North Atlantic upper water reaches the Norwegian Sea and is converted into cold dense overflow water as part of the thermohaline overturning in the northern North Atlantic and Nordic Seas. The upper water column is characterised by poleward moving Eastern North Atlantic Water (ENAW), which is warmer and saltier than the subpolar mode waters of the Iceland Basin, which also contribute to the Nordic Sea inflow. Below 1200 m the deep Labrador Sea Water (LSW) is trapped by the shallowing topography to the north, which prevents through flow but allows recirculation within the basin. The Rockall Trough experiences a strong seasonal signal in temperature and salinity with deep convective winter mixing to typically 600 m or more and the formation of a warm fresh summer surface layer. The time series reveals interannual changes in salinity of ±0.05 in the ENAW and ±0.04 in the LSW. The deep water freshening events are of a magnitude greater than that expected from changes in source characteristics of the LSW, and are shown to represent periodic pulses of newer LSW into a recirculating reservior. The mean poleward transport of ENAW is 3.7 Sv above 1200 dbar (of which 3.0 Sv is carried by the shelf edge current) but shows a high-level interannual variability, ranging from 0 to 8 Sv over the 23 yr period. The shelf edge current is shown to have a changing thermohaline structure and a baroclinic transport that varies from 0 to 8 Sv. The interannual signal in the total transport dominates the observations, and no evidence is found of a seasonal signal. Article in Journal/Newspaper Iceland Labrador Sea Nordic Sea Nordic Seas North Atlantic Norwegian Sea Natural Environment Research Council: NERC Open Research Archive Norwegian Sea Rockall Trough ENVELOPE(-15.036,-15.036,53.825,53.825) Thompson Ridge ENVELOPE(-146.083,-146.083,-76.450,-76.450) Deep Sea Research Part I: Oceanographic Research Papers 47 7 1303 1332 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
unknown |
description |
A time series of a standard hydrographic section in the northern Rockall Trough spanning 23 yr is examined for changes in water mass properties and transport levels. The Rockall Trough is situated west of the British Isles and separated from the Iceland Basin by the Hatton and Rockall Banks and from the Nordic Seas by the shallow (500 m) Wyville–Thompson ridge. It is one pathway by which warm North Atlantic upper water reaches the Norwegian Sea and is converted into cold dense overflow water as part of the thermohaline overturning in the northern North Atlantic and Nordic Seas. The upper water column is characterised by poleward moving Eastern North Atlantic Water (ENAW), which is warmer and saltier than the subpolar mode waters of the Iceland Basin, which also contribute to the Nordic Sea inflow. Below 1200 m the deep Labrador Sea Water (LSW) is trapped by the shallowing topography to the north, which prevents through flow but allows recirculation within the basin. The Rockall Trough experiences a strong seasonal signal in temperature and salinity with deep convective winter mixing to typically 600 m or more and the formation of a warm fresh summer surface layer. The time series reveals interannual changes in salinity of ±0.05 in the ENAW and ±0.04 in the LSW. The deep water freshening events are of a magnitude greater than that expected from changes in source characteristics of the LSW, and are shown to represent periodic pulses of newer LSW into a recirculating reservior. The mean poleward transport of ENAW is 3.7 Sv above 1200 dbar (of which 3.0 Sv is carried by the shelf edge current) but shows a high-level interannual variability, ranging from 0 to 8 Sv over the 23 yr period. The shelf edge current is shown to have a changing thermohaline structure and a baroclinic transport that varies from 0 to 8 Sv. The interannual signal in the total transport dominates the observations, and no evidence is found of a seasonal signal. |
format |
Article in Journal/Newspaper |
author |
Holliday, N.P. Pollard, R.T. Read, J.F. Leach, H. |
spellingShingle |
Holliday, N.P. Pollard, R.T. Read, J.F. Leach, H. Water mass properties and fluxes in the Rockall Trough, 1975-1998 |
author_facet |
Holliday, N.P. Pollard, R.T. Read, J.F. Leach, H. |
author_sort |
Holliday, N.P. |
title |
Water mass properties and fluxes in the Rockall Trough, 1975-1998 |
title_short |
Water mass properties and fluxes in the Rockall Trough, 1975-1998 |
title_full |
Water mass properties and fluxes in the Rockall Trough, 1975-1998 |
title_fullStr |
Water mass properties and fluxes in the Rockall Trough, 1975-1998 |
title_full_unstemmed |
Water mass properties and fluxes in the Rockall Trough, 1975-1998 |
title_sort |
water mass properties and fluxes in the rockall trough, 1975-1998 |
publishDate |
2000 |
url |
http://nora.nerc.ac.uk/id/eprint/108932/ https://doi.org/10.1016/S0967-0637(99)00109-0 |
long_lat |
ENVELOPE(-15.036,-15.036,53.825,53.825) ENVELOPE(-146.083,-146.083,-76.450,-76.450) |
geographic |
Norwegian Sea Rockall Trough Thompson Ridge |
geographic_facet |
Norwegian Sea Rockall Trough Thompson Ridge |
genre |
Iceland Labrador Sea Nordic Sea Nordic Seas North Atlantic Norwegian Sea |
genre_facet |
Iceland Labrador Sea Nordic Sea Nordic Seas North Atlantic Norwegian Sea |
op_relation |
Holliday, N.P. orcid:0000-0002-9733-8002 Pollard, R.T.; Read, J.F.; Leach, H. 2000 Water mass properties and fluxes in the Rockall Trough, 1975-1998. Deep-Sea Research I, 47 (7). 1303-1332. https://doi.org/10.1016/S0967-0637(99)00109-0 <https://doi.org/10.1016/S0967-0637(99)00109-0> |
op_doi |
https://doi.org/10.1016/S0967-0637(99)00109-0 |
container_title |
Deep Sea Research Part I: Oceanographic Research Papers |
container_volume |
47 |
container_issue |
7 |
container_start_page |
1303 |
op_container_end_page |
1332 |
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1766039186835505152 |