Seismic reflection along the path of the Mediterranean Undercurrent
Seismic reflection profiling is applied to the study of large scale physical oceanographic processes in the Gulf of Cádiz and western Iberian coast, coinciding with the path of the Mediterranean Undercurrent. The multi-channel seismic reflection method provides clear images of thermohaline fine stru...
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Online Access: | http://hdl.handle.net/10553/49049 https://doi.org/10.1016/j.csr.2009.05.017 |
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ftunivlaspalmas:oai:https://accedacris.ulpgc.es:10553/49049 2023-05-15T17:25:27+02:00 Seismic reflection along the path of the Mediterranean Undercurrent Buffett, G. G. Biescas, B. Pelegrí Llopart,José Luis Machín, F. Sallarès, V. Carbonell, R. Klaeschen, D. Hobbs, R. Hobbs, Richard Carbonell, Ramon Buffett, Grant George Sallares, Valenti Pelegri, Josep Machin, Francisco Biescas Gorriz, Berta 24597494800 7801342506 7003869003 6602804374 55890549500 7101720299 6603864860 7202266452 6816662 2373642 358123 1451397 755845 596160 444536 227869 2009 http://hdl.handle.net/10553/49049 https://doi.org/10.1016/j.csr.2009.05.017 eng eng 0278-4343 Continental Shelf Research 0278-4343 http://hdl.handle.net/10553/49049 doi:10.1016/j.csr.2009.05.017 69249209739 000273061800009 1860 1848 29 F-1054-2013 A-5729-2009 D-3683-2013 Q-1720-2017 L-5815-2014 C-7847-2014 A-9287-2009 No ID Continental Shelf Research [ISSN 0278-4343], v. 29, p. 1848-1860 251007 Oceanografía física Seismic oceanography Mediterranean Undercurrent Thermohaline fine structure Mixing Entrainment Temperature Salinity Amplitude 2009 ftunivlaspalmas https://doi.org/10.1016/j.csr.2009.05.017 2020-02-12T00:09:52Z Seismic reflection profiling is applied to the study of large scale physical oceanographic processes in the Gulf of Cádiz and western Iberian coast, coinciding with the path of the Mediterranean Undercurrent. The multi-channel seismic reflection method provides clear images of thermohaline fine structure with a horizontal resolution approximately two orders of magnitude higher than CTD casting. The seismic data are compared with co-located historical oceanographic data. Three seismic reflectivity zones are identified: North Atlantic Central Water, Mediterranean Water and North Atlantic Deep Water. Seismic evidence for the path of the Mediterranean Undercurrent is found in the near-slope reflectivity patterns, with rising reflectors between about 500 and 1500 m. However, the core of the undercurrent is largely transparent. Seismic images show that central and, particularly, intermediate Mediterranean Waters have fine structure coherent over horizontal distances of several tens of kilometers. However, the intensity of the reflectors, and their horizontal coherence, decreases downstream. This change in seismic reflectivity is probably the result of diminished vertical thermohaline contrasts between adjacent water masses, so that double-diffusion processes become unable to sustain temperature and salinity staircases. Comparison of root-mean-square seismic amplitudes with temperature and salinity differences between the Mediterranean Undercurrent and the overlying central waters suggests a causal relationship between observed thermohaline fine structure and true seismic amplitudes. We estimate that, within this intermediate water stratum, impedance contrasts are mainly controlled by sound speed contrasts (a factor between 3.5 and 10 times larger than density contrasts), which are mainly controlled by temperature contrasts (a factor between 1.5 and 5 times larger than salinity contrasts). Other/Unknown Material North Atlantic Deep Water North Atlantic Universidad de Las Palmas de Gran Canaria: Acceda Continental Shelf Research 29 15 1848 1860 |
institution |
Open Polar |
collection |
Universidad de Las Palmas de Gran Canaria: Acceda |
op_collection_id |
ftunivlaspalmas |
language |
English |
topic |
251007 Oceanografía física Seismic oceanography Mediterranean Undercurrent Thermohaline fine structure Mixing Entrainment Temperature Salinity Amplitude |
spellingShingle |
251007 Oceanografía física Seismic oceanography Mediterranean Undercurrent Thermohaline fine structure Mixing Entrainment Temperature Salinity Amplitude Buffett, G. G. Biescas, B. Pelegrí Llopart,José Luis Machín, F. Sallarès, V. Carbonell, R. Klaeschen, D. Hobbs, R. Seismic reflection along the path of the Mediterranean Undercurrent |
topic_facet |
251007 Oceanografía física Seismic oceanography Mediterranean Undercurrent Thermohaline fine structure Mixing Entrainment Temperature Salinity Amplitude |
description |
Seismic reflection profiling is applied to the study of large scale physical oceanographic processes in the Gulf of Cádiz and western Iberian coast, coinciding with the path of the Mediterranean Undercurrent. The multi-channel seismic reflection method provides clear images of thermohaline fine structure with a horizontal resolution approximately two orders of magnitude higher than CTD casting. The seismic data are compared with co-located historical oceanographic data. Three seismic reflectivity zones are identified: North Atlantic Central Water, Mediterranean Water and North Atlantic Deep Water. Seismic evidence for the path of the Mediterranean Undercurrent is found in the near-slope reflectivity patterns, with rising reflectors between about 500 and 1500 m. However, the core of the undercurrent is largely transparent. Seismic images show that central and, particularly, intermediate Mediterranean Waters have fine structure coherent over horizontal distances of several tens of kilometers. However, the intensity of the reflectors, and their horizontal coherence, decreases downstream. This change in seismic reflectivity is probably the result of diminished vertical thermohaline contrasts between adjacent water masses, so that double-diffusion processes become unable to sustain temperature and salinity staircases. Comparison of root-mean-square seismic amplitudes with temperature and salinity differences between the Mediterranean Undercurrent and the overlying central waters suggests a causal relationship between observed thermohaline fine structure and true seismic amplitudes. We estimate that, within this intermediate water stratum, impedance contrasts are mainly controlled by sound speed contrasts (a factor between 3.5 and 10 times larger than density contrasts), which are mainly controlled by temperature contrasts (a factor between 1.5 and 5 times larger than salinity contrasts). |
author2 |
Hobbs, Richard Carbonell, Ramon Buffett, Grant George Sallares, Valenti Pelegri, Josep Machin, Francisco Biescas Gorriz, Berta 24597494800 7801342506 7003869003 6602804374 55890549500 7101720299 6603864860 7202266452 6816662 2373642 358123 1451397 755845 596160 444536 227869 |
author |
Buffett, G. G. Biescas, B. Pelegrí Llopart,José Luis Machín, F. Sallarès, V. Carbonell, R. Klaeschen, D. Hobbs, R. |
author_facet |
Buffett, G. G. Biescas, B. Pelegrí Llopart,José Luis Machín, F. Sallarès, V. Carbonell, R. Klaeschen, D. Hobbs, R. |
author_sort |
Buffett, G. G. |
title |
Seismic reflection along the path of the Mediterranean Undercurrent |
title_short |
Seismic reflection along the path of the Mediterranean Undercurrent |
title_full |
Seismic reflection along the path of the Mediterranean Undercurrent |
title_fullStr |
Seismic reflection along the path of the Mediterranean Undercurrent |
title_full_unstemmed |
Seismic reflection along the path of the Mediterranean Undercurrent |
title_sort |
seismic reflection along the path of the mediterranean undercurrent |
publisher |
0278-4343 |
publishDate |
2009 |
url |
http://hdl.handle.net/10553/49049 https://doi.org/10.1016/j.csr.2009.05.017 |
genre |
North Atlantic Deep Water North Atlantic |
genre_facet |
North Atlantic Deep Water North Atlantic |
op_source |
Continental Shelf Research [ISSN 0278-4343], v. 29, p. 1848-1860 |
op_relation |
Continental Shelf Research 0278-4343 http://hdl.handle.net/10553/49049 doi:10.1016/j.csr.2009.05.017 69249209739 000273061800009 1860 1848 29 F-1054-2013 A-5729-2009 D-3683-2013 Q-1720-2017 L-5815-2014 C-7847-2014 A-9287-2009 No ID |
op_doi |
https://doi.org/10.1016/j.csr.2009.05.017 |
container_title |
Continental Shelf Research |
container_volume |
29 |
container_issue |
15 |
container_start_page |
1848 |
op_container_end_page |
1860 |
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1766116886134652928 |