Meddies and decadal changes at the Azores Front from 1980 to 2000
Twenty years of time series observations from the deep-sea mooring KIEL276 are used to obtain information on the frequency and propagation of meddies (Mediterranean Water eddies), on long-term changes in flow properties, and on a possible relation to the North Atlantic Oscillation. The mooring was s...
Published in: | Deep Sea Research Part II: Topical Studies in Oceanography |
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Online Access: | https://oceanrep.geomar.de/id/eprint/3318/ https://oceanrep.geomar.de/id/eprint/3318/1/1-s2.0-S0967064504003108-main.pdf https://doi.org/10.1016/j.dsr2.2004.12.010 |
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ftoceanrep:oai:oceanrep.geomar.de:3318 2023-05-15T17:29:14+02:00 Meddies and decadal changes at the Azores Front from 1980 to 2000 Siedler, Gerold Armi, Laurence Müller, Thomas J. 2005 text https://oceanrep.geomar.de/id/eprint/3318/ https://oceanrep.geomar.de/id/eprint/3318/1/1-s2.0-S0967064504003108-main.pdf https://doi.org/10.1016/j.dsr2.2004.12.010 en eng Elsevier https://oceanrep.geomar.de/id/eprint/3318/1/1-s2.0-S0967064504003108-main.pdf Siedler, G., Armi, L. and Müller, T. J. (2005) Meddies and decadal changes at the Azores Front from 1980 to 2000. Deep Sea Research Part II: Topical Studies in Oceanography, 52 (3-4). pp. 583-604. DOI 10.1016/j.dsr2.2004.12.010 <https://doi.org/10.1016/j.dsr2.2004.12.010>. doi:10.1016/j.dsr2.2004.12.010 info:eu-repo/semantics/restrictedAccess Article PeerReviewed 2005 ftoceanrep https://doi.org/10.1016/j.dsr2.2004.12.010 2023-04-07T14:47:34Z Twenty years of time series observations from the deep-sea mooring KIEL276 are used to obtain information on the frequency and propagation of meddies (Mediterranean Water eddies), on long-term changes in flow properties, and on a possible relation to the North Atlantic Oscillation. The mooring was set at the nominal position 33°N, 22°W at a water depth of more than 5200 m in the northern Canary Basin. It is located near the southern boundary of the Azores Current (AC), which is part of the North Atlantic subtropical gyre, and also in the large-scale Mediterranean Water (MW) tongue originating from the Strait of Gibraltar. The amplitudes of time-varying vertical quasi-geostrophic modes and the correlation of current and temperature changes at levels in the MW and the North Atlantic Central Water above are used to identify meddies. A total of 10 meddies passed the mooring during the period 1980–2000. Half of the events can be related to earlier observations. Directional changes in meddy-related velocities are used to estimate speeds and directions of meddy propagation. Directions of propagation are very homogeneous, with all the 10 meddies observed propagating with a southward velocity component within a sector of 90°, and typical speeds are 2–3 cm/s. Meddy occurrence was uneven in time, with six meddies found during the first four years and only four meddies during the remaining 16 years. Decadal changes show the annual-mean and the fluctuating kinetic energy levels at the site changing from lower values in the 1980s to high values in the 1990s. This change appears to be correlated with variations in the North Atlantic Oscillation (NAO) index, with a delay in oceanic response of about 3 years. A conceptual model of AC meanders is used to identify meander signals in the upper-layer time series. The AC axis appears to be closer to the site during the 1990s than during the preceding decade and indicates a southward or southwestward displacement of the AC with increasingly positive values of the NAO index. Meddy ... Article in Journal/Newspaper North Atlantic North Atlantic oscillation OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Deep Sea Research Part II: Topical Studies in Oceanography 52 3-4 583 604 |
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Open Polar |
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OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
op_collection_id |
ftoceanrep |
language |
English |
description |
Twenty years of time series observations from the deep-sea mooring KIEL276 are used to obtain information on the frequency and propagation of meddies (Mediterranean Water eddies), on long-term changes in flow properties, and on a possible relation to the North Atlantic Oscillation. The mooring was set at the nominal position 33°N, 22°W at a water depth of more than 5200 m in the northern Canary Basin. It is located near the southern boundary of the Azores Current (AC), which is part of the North Atlantic subtropical gyre, and also in the large-scale Mediterranean Water (MW) tongue originating from the Strait of Gibraltar. The amplitudes of time-varying vertical quasi-geostrophic modes and the correlation of current and temperature changes at levels in the MW and the North Atlantic Central Water above are used to identify meddies. A total of 10 meddies passed the mooring during the period 1980–2000. Half of the events can be related to earlier observations. Directional changes in meddy-related velocities are used to estimate speeds and directions of meddy propagation. Directions of propagation are very homogeneous, with all the 10 meddies observed propagating with a southward velocity component within a sector of 90°, and typical speeds are 2–3 cm/s. Meddy occurrence was uneven in time, with six meddies found during the first four years and only four meddies during the remaining 16 years. Decadal changes show the annual-mean and the fluctuating kinetic energy levels at the site changing from lower values in the 1980s to high values in the 1990s. This change appears to be correlated with variations in the North Atlantic Oscillation (NAO) index, with a delay in oceanic response of about 3 years. A conceptual model of AC meanders is used to identify meander signals in the upper-layer time series. The AC axis appears to be closer to the site during the 1990s than during the preceding decade and indicates a southward or southwestward displacement of the AC with increasingly positive values of the NAO index. Meddy ... |
format |
Article in Journal/Newspaper |
author |
Siedler, Gerold Armi, Laurence Müller, Thomas J. |
spellingShingle |
Siedler, Gerold Armi, Laurence Müller, Thomas J. Meddies and decadal changes at the Azores Front from 1980 to 2000 |
author_facet |
Siedler, Gerold Armi, Laurence Müller, Thomas J. |
author_sort |
Siedler, Gerold |
title |
Meddies and decadal changes at the Azores Front from 1980 to 2000 |
title_short |
Meddies and decadal changes at the Azores Front from 1980 to 2000 |
title_full |
Meddies and decadal changes at the Azores Front from 1980 to 2000 |
title_fullStr |
Meddies and decadal changes at the Azores Front from 1980 to 2000 |
title_full_unstemmed |
Meddies and decadal changes at the Azores Front from 1980 to 2000 |
title_sort |
meddies and decadal changes at the azores front from 1980 to 2000 |
publisher |
Elsevier |
publishDate |
2005 |
url |
https://oceanrep.geomar.de/id/eprint/3318/ https://oceanrep.geomar.de/id/eprint/3318/1/1-s2.0-S0967064504003108-main.pdf https://doi.org/10.1016/j.dsr2.2004.12.010 |
genre |
North Atlantic North Atlantic oscillation |
genre_facet |
North Atlantic North Atlantic oscillation |
op_relation |
https://oceanrep.geomar.de/id/eprint/3318/1/1-s2.0-S0967064504003108-main.pdf Siedler, G., Armi, L. and Müller, T. J. (2005) Meddies and decadal changes at the Azores Front from 1980 to 2000. Deep Sea Research Part II: Topical Studies in Oceanography, 52 (3-4). pp. 583-604. DOI 10.1016/j.dsr2.2004.12.010 <https://doi.org/10.1016/j.dsr2.2004.12.010>. doi:10.1016/j.dsr2.2004.12.010 |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1016/j.dsr2.2004.12.010 |
container_title |
Deep Sea Research Part II: Topical Studies in Oceanography |
container_volume |
52 |
container_issue |
3-4 |
container_start_page |
583 |
op_container_end_page |
604 |
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