The variable and changing Southern Ocean Silicate Front: Insights from the CESM Large Ensemble
The location of the Southern Ocean Silicate Front (SF) is a key indicator of physical circulation, biological productivity, and biogeography, but its variability in space and time is currently not well understood due to a lack of time-varying nutrient observations. This study provides a first estima...
Published in: | Global Biogeochemical Cycles |
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Language: | English |
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2018
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Online Access: | https://doi.org/10.1029/2017GB005816 |
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ftncar:oai:drupal-site.org:articles_21845 2023-09-05T13:12:47+02:00 The variable and changing Southern Ocean Silicate Front: Insights from the CESM Large Ensemble Freeman, Natalie M. (author) Lovenduski, Nicole S. (author) Munro, David R. (author) Krumhardt, Kristen M. (author) Lindsay, Keith (author) Long, Matthew C. (author) Maclennan, Michelle (author) 2018-05-01 https://doi.org/10.1029/2017GB005816 en eng Global Biogeochemical Cycles--Global Biogeochem. Cycles--08866236 articles:21845 ark:/85065/d7280bfg doi:10.1029/2017GB005816 Copyright 2018 American Geophysical Union. article Text 2018 ftncar https://doi.org/10.1029/2017GB005816 2023-08-14T18:50:04Z The location of the Southern Ocean Silicate Front (SF) is a key indicator of physical circulation, biological productivity, and biogeography, but its variability in space and time is currently not well understood due to a lack of time-varying nutrient observations. This study provides a first estimate of the spatiotemporal variability of the SF, defined using the silicate-to-nitrate (Si:N) ratio as simulated by the Community Earth System Model (CESM) Large Ensemble (1920-2100), and its response to a changing Southern Ocean. The latitude where Si:N=1 largely coincides with regions of high gradients in silicate and the observed position of the Antarctic Polar Front (PF) and serves as an indicator of waters with adequate nutrients available for diatom growth. On seasonal to interdecadal time scales, variability in the location of the SF is largely determined by biological nutrient utilization and Southern Ocean bathymetry, respectively. From 1920 to 2100, under historical and RCP8.5 forcing, the zonally averaged SF shifts poleward by approximate to 3 degrees latitude, with no discernible shift in the position of the simulated location of the PF or the core of the Antarctic Circumpolar Current. A more poleward SF is primarily driven by long-term reductions in silicate and nitrate concentrations at the surface as a consequence of greater iron availability and a warmer, more stratified Southern Ocean. These results suggest a decoupling of the SF and PF by the end of the century, with implications for local biogeography, global thermocline nutrient cycling, and the interpretation of paleoclimate records from deep sea sediments. Article in Journal/Newspaper Antarc* Antarctic Southern Ocean OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research) Antarctic Southern Ocean The Antarctic Global Biogeochemical Cycles 32 5 752 768 |
institution |
Open Polar |
collection |
OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research) |
op_collection_id |
ftncar |
language |
English |
description |
The location of the Southern Ocean Silicate Front (SF) is a key indicator of physical circulation, biological productivity, and biogeography, but its variability in space and time is currently not well understood due to a lack of time-varying nutrient observations. This study provides a first estimate of the spatiotemporal variability of the SF, defined using the silicate-to-nitrate (Si:N) ratio as simulated by the Community Earth System Model (CESM) Large Ensemble (1920-2100), and its response to a changing Southern Ocean. The latitude where Si:N=1 largely coincides with regions of high gradients in silicate and the observed position of the Antarctic Polar Front (PF) and serves as an indicator of waters with adequate nutrients available for diatom growth. On seasonal to interdecadal time scales, variability in the location of the SF is largely determined by biological nutrient utilization and Southern Ocean bathymetry, respectively. From 1920 to 2100, under historical and RCP8.5 forcing, the zonally averaged SF shifts poleward by approximate to 3 degrees latitude, with no discernible shift in the position of the simulated location of the PF or the core of the Antarctic Circumpolar Current. A more poleward SF is primarily driven by long-term reductions in silicate and nitrate concentrations at the surface as a consequence of greater iron availability and a warmer, more stratified Southern Ocean. These results suggest a decoupling of the SF and PF by the end of the century, with implications for local biogeography, global thermocline nutrient cycling, and the interpretation of paleoclimate records from deep sea sediments. |
author2 |
Freeman, Natalie M. (author) Lovenduski, Nicole S. (author) Munro, David R. (author) Krumhardt, Kristen M. (author) Lindsay, Keith (author) Long, Matthew C. (author) Maclennan, Michelle (author) |
format |
Article in Journal/Newspaper |
title |
The variable and changing Southern Ocean Silicate Front: Insights from the CESM Large Ensemble |
spellingShingle |
The variable and changing Southern Ocean Silicate Front: Insights from the CESM Large Ensemble |
title_short |
The variable and changing Southern Ocean Silicate Front: Insights from the CESM Large Ensemble |
title_full |
The variable and changing Southern Ocean Silicate Front: Insights from the CESM Large Ensemble |
title_fullStr |
The variable and changing Southern Ocean Silicate Front: Insights from the CESM Large Ensemble |
title_full_unstemmed |
The variable and changing Southern Ocean Silicate Front: Insights from the CESM Large Ensemble |
title_sort |
variable and changing southern ocean silicate front: insights from the cesm large ensemble |
publishDate |
2018 |
url |
https://doi.org/10.1029/2017GB005816 |
geographic |
Antarctic Southern Ocean The Antarctic |
geographic_facet |
Antarctic Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_relation |
Global Biogeochemical Cycles--Global Biogeochem. Cycles--08866236 articles:21845 ark:/85065/d7280bfg doi:10.1029/2017GB005816 |
op_rights |
Copyright 2018 American Geophysical Union. |
op_doi |
https://doi.org/10.1029/2017GB005816 |
container_title |
Global Biogeochemical Cycles |
container_volume |
32 |
container_issue |
5 |
container_start_page |
752 |
op_container_end_page |
768 |
_version_ |
1776201761619443712 |