On the intermittent occurrence of open-ocean polynyas in a multi-century high-resolution preindustrial earth system model simulation
A 500-year-long high-resolution Community Earth System Model simulation under preindustrial radiative forcing produces Maud Rise Polynyas (MRPs) and Weddell Sea Polynya (WSP) events intermittently from decadal (MRP) to multidecadal (WSP) timescales. This periodicity is correlated with the variation...
Published in: | Journal of Geophysical Research: Oceans |
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2022
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Online Access: | https://doi.org/10.1029/2021JC017672 |
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ftncar:oai:drupal-site.org:articles_25285 2024-04-28T07:56:37+00:00 On the intermittent occurrence of open-ocean polynyas in a multi-century high-resolution preindustrial earth system model simulation Diao, Xiliang (author) Stössel, Achim (author) Chang, Ping (author) Danabasoglu, Gokhan (author) Yeager, Stephen G. (author) Gopal, Abishek (author) Wang, Hong (author) Zhang, Shaoqing (author) 2022-04 https://doi.org/10.1029/2021JC017672 en eng Journal of Geophysical Research: Oceans--JGR Oceans--2169-9275--2169-9291 articles:25285 doi:10.1029/2021JC017672 ark:/85065/d7hx1h9q Copyright 2022 American Geophysical Union. article Text 2022 ftncar https://doi.org/10.1029/2021JC017672 2024-04-04T17:34:52Z A 500-year-long high-resolution Community Earth System Model simulation under preindustrial radiative forcing produces Maud Rise Polynyas (MRPs) and Weddell Sea Polynya (WSP) events intermittently from decadal (MRP) to multidecadal (WSP) timescales. This periodicity is correlated with the variation of a regional Southern Annular Mode (SAM) index (evaluated regionally instead of circum-Antarctic) with corresponding variations of precipitation and winds over the Weddell Sea. A negative index causes the upper-ocean salinity to increase over multiple decades. Ultimately, brine rejection during seasonal sea-ice formation superimposed on the multidecadal increase raises the upper-ocean salinity beyond the tipping point for triggering deep convection that leads to polynyas. The initiation of polynya events is thus controlled by surface properties while the location of initiation is determined by bathymetric features. The persistent Taylor column effect, which is well represented by the high-resolution model topography of the Maud Rise seamount, preconditions this region for MRP initiation. Therefore, MRPs form more frequently than WSPs in the simulation. When the upper-ocean salinity is high, deep convection in the MRP region tends to be stronger, in which case MRPs are also more likely to grow into WSPs. Once WSPs emerge, they affect the regional atmospheric circulation and associated variables. We propose a regional coupled ocean-atmosphere mechanism to explain both the periodic emergence of polynyas and the periodic variation of the regional SAM index. Although the temperature and salinity of Weddell Deep Water show upward trends due to model drift, these density-compensating changes do not affect the frequency of polynya formation. 1852977 30964 Article in Journal/Newspaper Antarc* Antarctic Sea ice Weddell Sea OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research) Journal of Geophysical Research: Oceans 127 4 |
institution |
Open Polar |
collection |
OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research) |
op_collection_id |
ftncar |
language |
English |
description |
A 500-year-long high-resolution Community Earth System Model simulation under preindustrial radiative forcing produces Maud Rise Polynyas (MRPs) and Weddell Sea Polynya (WSP) events intermittently from decadal (MRP) to multidecadal (WSP) timescales. This periodicity is correlated with the variation of a regional Southern Annular Mode (SAM) index (evaluated regionally instead of circum-Antarctic) with corresponding variations of precipitation and winds over the Weddell Sea. A negative index causes the upper-ocean salinity to increase over multiple decades. Ultimately, brine rejection during seasonal sea-ice formation superimposed on the multidecadal increase raises the upper-ocean salinity beyond the tipping point for triggering deep convection that leads to polynyas. The initiation of polynya events is thus controlled by surface properties while the location of initiation is determined by bathymetric features. The persistent Taylor column effect, which is well represented by the high-resolution model topography of the Maud Rise seamount, preconditions this region for MRP initiation. Therefore, MRPs form more frequently than WSPs in the simulation. When the upper-ocean salinity is high, deep convection in the MRP region tends to be stronger, in which case MRPs are also more likely to grow into WSPs. Once WSPs emerge, they affect the regional atmospheric circulation and associated variables. We propose a regional coupled ocean-atmosphere mechanism to explain both the periodic emergence of polynyas and the periodic variation of the regional SAM index. Although the temperature and salinity of Weddell Deep Water show upward trends due to model drift, these density-compensating changes do not affect the frequency of polynya formation. 1852977 30964 |
author2 |
Diao, Xiliang (author) Stössel, Achim (author) Chang, Ping (author) Danabasoglu, Gokhan (author) Yeager, Stephen G. (author) Gopal, Abishek (author) Wang, Hong (author) Zhang, Shaoqing (author) |
format |
Article in Journal/Newspaper |
title |
On the intermittent occurrence of open-ocean polynyas in a multi-century high-resolution preindustrial earth system model simulation |
spellingShingle |
On the intermittent occurrence of open-ocean polynyas in a multi-century high-resolution preindustrial earth system model simulation |
title_short |
On the intermittent occurrence of open-ocean polynyas in a multi-century high-resolution preindustrial earth system model simulation |
title_full |
On the intermittent occurrence of open-ocean polynyas in a multi-century high-resolution preindustrial earth system model simulation |
title_fullStr |
On the intermittent occurrence of open-ocean polynyas in a multi-century high-resolution preindustrial earth system model simulation |
title_full_unstemmed |
On the intermittent occurrence of open-ocean polynyas in a multi-century high-resolution preindustrial earth system model simulation |
title_sort |
on the intermittent occurrence of open-ocean polynyas in a multi-century high-resolution preindustrial earth system model simulation |
publishDate |
2022 |
url |
https://doi.org/10.1029/2021JC017672 |
genre |
Antarc* Antarctic Sea ice Weddell Sea |
genre_facet |
Antarc* Antarctic Sea ice Weddell Sea |
op_relation |
Journal of Geophysical Research: Oceans--JGR Oceans--2169-9275--2169-9291 articles:25285 doi:10.1029/2021JC017672 ark:/85065/d7hx1h9q |
op_rights |
Copyright 2022 American Geophysical Union. |
op_doi |
https://doi.org/10.1029/2021JC017672 |
container_title |
Journal of Geophysical Research: Oceans |
container_volume |
127 |
container_issue |
4 |
_version_ |
1797584057182191616 |