North Pacific climate response to freshwater forcing in the subarctic North Atlantic: Oceanic and atmospheric pathways
Sudden changes of the Atlantic meridional overturning circulation (AMOC) are believed to have caused large, abrupt climate changes over many parts of the globe during the last glacial and deglacial period. This study investigates the mechanisms by which a large freshwater input to the subarctic Nort...
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ftncar:oai:drupal-site.org:articles_15391 2023-09-05T13:11:35+02:00 North Pacific climate response to freshwater forcing in the subarctic North Atlantic: Oceanic and atmospheric pathways Okumura, Yuko (author) Deser, Clara (author) Hu, Aixue (author) Timmerman, Axel (author) Xie, Shang-Ping (author) 2009-03-01 application/pdf http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-002-462 https://doi.org/10.1175/2008JCLI2511.1 en eng American Meteorological Society Journal of Climate http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-002-462 doi:10.1175/2008JCLI2511.1 ark:/85065/d7w95b61 Copyright 2009 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work. North Pacific Ocean Freshwater Forcing Teleconnections Air-sea interaction Text article 2009 ftncar https://doi.org/10.1175/2008JCLI2511.1 2023-08-14T18:42:02Z Sudden changes of the Atlantic meridional overturning circulation (AMOC) are believed to have caused large, abrupt climate changes over many parts of the globe during the last glacial and deglacial period. This study investigates the mechanisms by which a large freshwater input to the subarctic North Atlantic and an attendant rapid weakening of the AMOC influence North Pacific climate by analyzing four different ocean–atmosphere coupled general circulation models (GCMs) under present-day or preindustrial boundary conditions. When the coupled GCMs are forced with a 1-Sv (Sv ≡ 10⁶ m³ s⁻¹) freshwater flux anomaly in the subarctic North Atlantic, the AMOC nearly shuts down and the North Atlantic cools significantly. The South Atlantic warms slightly, shifting the Atlantic intertropical convergence zone southward. In addition to this Atlantic ocean-atmosphere response, all of the models exhibit cooling of the North Pacific, especially along the oceanic frontal zone, consistent with paleoclimate reconstructions. The models also show deepening of the wintertime Aleutian low. Detailed analysis of one coupled GCM identifies both oceanic and atmospheric pathways from the Atlantic to the North Pacific. The oceanic teleconnection contributes a large part of the North Pacific cooling: the freshwater input to the North Atlantic raises sea level in the Arctic Ocean and reverses the Bering Strait throughflow, transporting colder, fresher water from the Arctic Ocean into the North Pacific. When the Bering Strait is closed, the cooling is greatly reduced, while the Aleutian low response is enhanced. Tropical SST anomalies in both the Atlantic and Pacific are found to be important for the equivalent barotropic response of the Aleutian low during boreal winter. The atmospheric bridge from the tropical North Atlantic is particularly important and quite sensitive to the mean state, which is poorly simulated in many coupled GCMs. The enhanced Aleutian low, in turn, cools the North Pacific by increasing surface heat fluxes and ... Article in Journal/Newspaper aleutian low Arctic Arctic Ocean Bering Strait North Atlantic Subarctic OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research) Arctic Arctic Ocean Bering Strait Pacific Journal of Climate 22 6 1424 1445 |
institution |
Open Polar |
collection |
OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research) |
op_collection_id |
ftncar |
language |
English |
topic |
North Pacific Ocean Freshwater Forcing Teleconnections Air-sea interaction |
spellingShingle |
North Pacific Ocean Freshwater Forcing Teleconnections Air-sea interaction North Pacific climate response to freshwater forcing in the subarctic North Atlantic: Oceanic and atmospheric pathways |
topic_facet |
North Pacific Ocean Freshwater Forcing Teleconnections Air-sea interaction |
description |
Sudden changes of the Atlantic meridional overturning circulation (AMOC) are believed to have caused large, abrupt climate changes over many parts of the globe during the last glacial and deglacial period. This study investigates the mechanisms by which a large freshwater input to the subarctic North Atlantic and an attendant rapid weakening of the AMOC influence North Pacific climate by analyzing four different ocean–atmosphere coupled general circulation models (GCMs) under present-day or preindustrial boundary conditions. When the coupled GCMs are forced with a 1-Sv (Sv ≡ 10⁶ m³ s⁻¹) freshwater flux anomaly in the subarctic North Atlantic, the AMOC nearly shuts down and the North Atlantic cools significantly. The South Atlantic warms slightly, shifting the Atlantic intertropical convergence zone southward. In addition to this Atlantic ocean-atmosphere response, all of the models exhibit cooling of the North Pacific, especially along the oceanic frontal zone, consistent with paleoclimate reconstructions. The models also show deepening of the wintertime Aleutian low. Detailed analysis of one coupled GCM identifies both oceanic and atmospheric pathways from the Atlantic to the North Pacific. The oceanic teleconnection contributes a large part of the North Pacific cooling: the freshwater input to the North Atlantic raises sea level in the Arctic Ocean and reverses the Bering Strait throughflow, transporting colder, fresher water from the Arctic Ocean into the North Pacific. When the Bering Strait is closed, the cooling is greatly reduced, while the Aleutian low response is enhanced. Tropical SST anomalies in both the Atlantic and Pacific are found to be important for the equivalent barotropic response of the Aleutian low during boreal winter. The atmospheric bridge from the tropical North Atlantic is particularly important and quite sensitive to the mean state, which is poorly simulated in many coupled GCMs. The enhanced Aleutian low, in turn, cools the North Pacific by increasing surface heat fluxes and ... |
author2 |
Okumura, Yuko (author) Deser, Clara (author) Hu, Aixue (author) Timmerman, Axel (author) Xie, Shang-Ping (author) |
format |
Article in Journal/Newspaper |
title |
North Pacific climate response to freshwater forcing in the subarctic North Atlantic: Oceanic and atmospheric pathways |
title_short |
North Pacific climate response to freshwater forcing in the subarctic North Atlantic: Oceanic and atmospheric pathways |
title_full |
North Pacific climate response to freshwater forcing in the subarctic North Atlantic: Oceanic and atmospheric pathways |
title_fullStr |
North Pacific climate response to freshwater forcing in the subarctic North Atlantic: Oceanic and atmospheric pathways |
title_full_unstemmed |
North Pacific climate response to freshwater forcing in the subarctic North Atlantic: Oceanic and atmospheric pathways |
title_sort |
north pacific climate response to freshwater forcing in the subarctic north atlantic: oceanic and atmospheric pathways |
publisher |
American Meteorological Society |
publishDate |
2009 |
url |
http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-002-462 https://doi.org/10.1175/2008JCLI2511.1 |
geographic |
Arctic Arctic Ocean Bering Strait Pacific |
geographic_facet |
Arctic Arctic Ocean Bering Strait Pacific |
genre |
aleutian low Arctic Arctic Ocean Bering Strait North Atlantic Subarctic |
genre_facet |
aleutian low Arctic Arctic Ocean Bering Strait North Atlantic Subarctic |
op_relation |
Journal of Climate http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-002-462 doi:10.1175/2008JCLI2511.1 ark:/85065/d7w95b61 |
op_rights |
Copyright 2009 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work. |
op_doi |
https://doi.org/10.1175/2008JCLI2511.1 |
container_title |
Journal of Climate |
container_volume |
22 |
container_issue |
6 |
container_start_page |
1424 |
op_container_end_page |
1445 |
_version_ |
1776205273751355392 |