Origin of freshwater and polynya water in the Arctic Ocean halocline in summer 2007
Extremely low summer sea-ice coverage in the Arctic Ocean in 2007 allowed extensive sampling and a wide quasi-synoptic hydrographic and δ18O dataset could be collected in the Eurasian Basin and the Makarov Basin up to the Alpha Ridge and the East Siberian continental margin. With the aim of determin...
Published in: | Progress in Oceanography |
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Main Authors: | , , , , , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
2011
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Subjects: | |
Online Access: | https://epic.awi.de/id/eprint/24034/ https://hdl.handle.net/10013/epic.39146 |
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ftawi:oai:epic.awi.de:24034 |
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record_format |
openpolar |
institution |
Open Polar |
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Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
op_collection_id |
ftawi |
language |
unknown |
description |
Extremely low summer sea-ice coverage in the Arctic Ocean in 2007 allowed extensive sampling and a wide quasi-synoptic hydrographic and δ18O dataset could be collected in the Eurasian Basin and the Makarov Basin up to the Alpha Ridge and the East Siberian continental margin. With the aim of determining the origin of freshwater in the halocline, fractions of river water and sea-ice meltwater in the upper 150 m were quantified by a combination of salinity and δ18O in the Eurasian Basin. Two methods, applying the preformed phosphate concentration (PO*) and the nitrate-to-phosphate ratio (N/P), were compared to further differentiate the marine fraction into Atlantic and Pacific-derived contributions. While PO*-based assessments systematically underestimate the contribution of Pacific-derived waters, N/P-based calculations overestimate Pacific-derived waters within the Transpolar Drift due to denitrification in bottom sediments at the Laptev Sea continental margin. Within the Eurasian Basin a west to east oriented front between net melting and production of sea-ice is observed. Outside the Atlantic regime dominated by net sea-ice melting, a pronounced layer influenced by brines released during sea-ice formation is present at about 30–50 m water depth with a maximum over the Lomonosov Ridge. The geographically distinct definition of this maximum demonstrates the rapid release and transport of signals from the shelf regions in discrete pulses within the Transpolar Drift. The ratio of sea-ice derived brine influence and river water is roughly constant within each layer of the Arctic Ocean halocline. The correlation between brine influence and river water reveals two clusters that can be assigned to the two main mechanisms of sea-ice formation within the Arctic Ocean. Over the open ocean or in polynyas at the continental slope where relatively small amounts of river water are found, sea-ice formation results in a linear correlation between brine influence and river water at salinities of about 32–34. In coastal polynyas in the shallow regions of the Laptev Sea and southern Kara Sea, sea-ice formation transports river water into the shelf’s bottom layer due to the close proximity to the river mouths. This process therefore results in waters that form a second linear correlation between brine influence and river water at salinities of about 30–32. Our study indicates which layers of the Arctic Ocean halocline are primarily influenced by sea-ice formation in coastal polynyas and which layers are primarily influenced by sea-ice formation over the open ocean. Accordingly we use the ratio of sea-ice derived brine influence and river water to link the maximum in brine influence within the Transpolar Drift with a pulse of shelf waters from the Laptev Sea that was likely released in summer 2005. |
format |
Article in Journal/Newspaper |
author |
Bauch, D. Rutgers v. d. Loeff, Michiel Andersen, N. Torres- Valdes, S. Bakker, K. Abrahamsen, E. P. |
spellingShingle |
Bauch, D. Rutgers v. d. Loeff, Michiel Andersen, N. Torres- Valdes, S. Bakker, K. Abrahamsen, E. P. Origin of freshwater and polynya water in the Arctic Ocean halocline in summer 2007 |
author_facet |
Bauch, D. Rutgers v. d. Loeff, Michiel Andersen, N. Torres- Valdes, S. Bakker, K. Abrahamsen, E. P. |
author_sort |
Bauch, D. |
title |
Origin of freshwater and polynya water in the Arctic Ocean halocline in summer 2007 |
title_short |
Origin of freshwater and polynya water in the Arctic Ocean halocline in summer 2007 |
title_full |
Origin of freshwater and polynya water in the Arctic Ocean halocline in summer 2007 |
title_fullStr |
Origin of freshwater and polynya water in the Arctic Ocean halocline in summer 2007 |
title_full_unstemmed |
Origin of freshwater and polynya water in the Arctic Ocean halocline in summer 2007 |
title_sort |
origin of freshwater and polynya water in the arctic ocean halocline in summer 2007 |
publishDate |
2011 |
url |
https://epic.awi.de/id/eprint/24034/ https://hdl.handle.net/10013/epic.39146 |
long_lat |
ENVELOPE(-120.000,-120.000,85.500,85.500) ENVELOPE(170.000,170.000,87.000,87.000) |
geographic |
Alpha Ridge Arctic Arctic Ocean Kara Sea Laptev Sea Makarov Basin Pacific |
geographic_facet |
Alpha Ridge Arctic Arctic Ocean Kara Sea Laptev Sea Makarov Basin Pacific |
genre |
alpha ridge Arctic Arctic Arctic Ocean Kara Sea laptev Laptev Sea Lomonosov Ridge makarov basin Sea ice |
genre_facet |
alpha ridge Arctic Arctic Arctic Ocean Kara Sea laptev Laptev Sea Lomonosov Ridge makarov basin Sea ice |
op_source |
EPIC3Progress in Oceanography., 91(4), pp. 482-495 |
op_relation |
Bauch, D. , Rutgers v. d. Loeff, M. orcid:0000-0003-1393-3742 , Andersen, N. , Torres- Valdes, S. , Bakker, K. and Abrahamsen, E. P. (2011) Origin of freshwater and polynya water in the Arctic Ocean halocline in summer 2007 , Progress in Oceanography., 91 (4), pp. 482-495 . doi:10.1016/j.pocean.2011.07.017 <https://doi.org/10.1016/j.pocean.2011.07.017> , hdl:10013/epic.39146 |
op_doi |
https://doi.org/10.1016/j.pocean.2011.07.017 |
container_title |
Progress in Oceanography |
container_volume |
91 |
container_issue |
4 |
container_start_page |
482 |
op_container_end_page |
495 |
_version_ |
1766353299422838784 |
spelling |
ftawi:oai:epic.awi.de:24034 2023-05-15T13:20:25+02:00 Origin of freshwater and polynya water in the Arctic Ocean halocline in summer 2007 Bauch, D. Rutgers v. d. Loeff, Michiel Andersen, N. Torres- Valdes, S. Bakker, K. Abrahamsen, E. P. 2011-12 https://epic.awi.de/id/eprint/24034/ https://hdl.handle.net/10013/epic.39146 unknown Bauch, D. , Rutgers v. d. Loeff, M. orcid:0000-0003-1393-3742 , Andersen, N. , Torres- Valdes, S. , Bakker, K. and Abrahamsen, E. P. (2011) Origin of freshwater and polynya water in the Arctic Ocean halocline in summer 2007 , Progress in Oceanography., 91 (4), pp. 482-495 . doi:10.1016/j.pocean.2011.07.017 <https://doi.org/10.1016/j.pocean.2011.07.017> , hdl:10013/epic.39146 EPIC3Progress in Oceanography., 91(4), pp. 482-495 Article isiRev 2011 ftawi https://doi.org/10.1016/j.pocean.2011.07.017 2021-12-24T15:34:55Z Extremely low summer sea-ice coverage in the Arctic Ocean in 2007 allowed extensive sampling and a wide quasi-synoptic hydrographic and δ18O dataset could be collected in the Eurasian Basin and the Makarov Basin up to the Alpha Ridge and the East Siberian continental margin. With the aim of determining the origin of freshwater in the halocline, fractions of river water and sea-ice meltwater in the upper 150 m were quantified by a combination of salinity and δ18O in the Eurasian Basin. Two methods, applying the preformed phosphate concentration (PO*) and the nitrate-to-phosphate ratio (N/P), were compared to further differentiate the marine fraction into Atlantic and Pacific-derived contributions. While PO*-based assessments systematically underestimate the contribution of Pacific-derived waters, N/P-based calculations overestimate Pacific-derived waters within the Transpolar Drift due to denitrification in bottom sediments at the Laptev Sea continental margin. Within the Eurasian Basin a west to east oriented front between net melting and production of sea-ice is observed. Outside the Atlantic regime dominated by net sea-ice melting, a pronounced layer influenced by brines released during sea-ice formation is present at about 30–50 m water depth with a maximum over the Lomonosov Ridge. The geographically distinct definition of this maximum demonstrates the rapid release and transport of signals from the shelf regions in discrete pulses within the Transpolar Drift. The ratio of sea-ice derived brine influence and river water is roughly constant within each layer of the Arctic Ocean halocline. The correlation between brine influence and river water reveals two clusters that can be assigned to the two main mechanisms of sea-ice formation within the Arctic Ocean. Over the open ocean or in polynyas at the continental slope where relatively small amounts of river water are found, sea-ice formation results in a linear correlation between brine influence and river water at salinities of about 32–34. In coastal polynyas in the shallow regions of the Laptev Sea and southern Kara Sea, sea-ice formation transports river water into the shelf’s bottom layer due to the close proximity to the river mouths. This process therefore results in waters that form a second linear correlation between brine influence and river water at salinities of about 30–32. Our study indicates which layers of the Arctic Ocean halocline are primarily influenced by sea-ice formation in coastal polynyas and which layers are primarily influenced by sea-ice formation over the open ocean. Accordingly we use the ratio of sea-ice derived brine influence and river water to link the maximum in brine influence within the Transpolar Drift with a pulse of shelf waters from the Laptev Sea that was likely released in summer 2005. Article in Journal/Newspaper alpha ridge Arctic Arctic Arctic Ocean Kara Sea laptev Laptev Sea Lomonosov Ridge makarov basin Sea ice Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) Alpha Ridge ENVELOPE(-120.000,-120.000,85.500,85.500) Arctic Arctic Ocean Kara Sea Laptev Sea Makarov Basin ENVELOPE(170.000,170.000,87.000,87.000) Pacific Progress in Oceanography 91 4 482 495 |