Evolution of the dynamics, area, and ice production of the Amundsen Sea Polynya, Antarctica, 2016–2021
<p>Polynyas are key sites of ice production during the winter and are important sites of biological activity and carbon sequestration during the summer. The Amundsen Sea Polynya (ASP) is the fourth largest Antarctic polynya, has recorded the highest primary productivity, and lies in an embayme...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-02-01
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| Series: | The Cryosphere |
| Online Access: | https://tc.copernicus.org/articles/17/457/2023/tc-17-457-2023.pdf |
| _version_ | 1811173203777683456 |
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| author | G. J. Macdonald G. J. Macdonald S. F. Ackley A. M. Mestas-Nuñez A. Blanco-Cabanillas |
| author_facet | G. J. Macdonald G. J. Macdonald S. F. Ackley A. M. Mestas-Nuñez A. Blanco-Cabanillas |
| author_sort | G. J. Macdonald |
| collection | DOAJ |
| description | <p>Polynyas are key sites of ice production during the winter and are
important sites of biological activity and carbon sequestration during the
summer. The Amundsen Sea Polynya (ASP) is the fourth largest Antarctic
polynya, has recorded the highest primary productivity, and lies in an
embayment of key oceanographic significance. However, knowledge of its
dynamics, and of sub-annual variations in its area and ice production, is
limited. In this study we primarily utilize Sentinel-1 synthetic aperture radar (SAR) imagery, sea ice concentration products, and climate reanalysis data, along with bathymetric
data, to analyze the ASP over the period November 2016–March 2021.
Specifically, we analyze (i) qualitative changes in the ASP's
characteristics and dynamics, as well as quantitative changes in (ii) summer
polynya area, and (iii) winter polynya area and ice production. From our
analysis of SAR imagery we find that ice produced by the ASP becomes stuck
in the vicinity of the polynya and sometimes flows back into the polynya,
contributing to its closure and limiting further ice production. The polynya
forms westward off a persistent chain of grounded icebergs that are located
at the site of a bathymetric high. Grounded icebergs also influence the
outflow of ice and facilitate the formation of a “secondary polynya” at
times. Additionally, unlike some polynyas, ice produced by the polynya flows
westward after formation, along the coast and into the neighboring sea
sector. During the summer and early winter, broader regional sea ice
conditions can play an important role in the polynya. The polynya opens in
all summers, but record-low sea ice conditions in 2016/17 cause it to become
part of the open ocean. During the winter, an average of 78 % of ice
production occurs in April–May and September–October, but large polynya
events often associated with high, southeasterly or easterly winds can
cause ice production throughout the winter. While passive microwave data or
daily sea ice concentration products remain key for analyzing variations in
polynya area and ice production, we find that the ability to directly
observe and qualitatively analyze the polynya at a high temporal and spatial
resolution with Sentinel-1 imagery provides important insights about the
behavior of the polynya that are not possible with those datasets.</p> |
| first_indexed | 2024-04-10T17:42:53Z |
| format | Article |
| id | doaj.art-1b582d7b9a5d472b9f31c7cb50d41e08 |
| institution | Directory Open Access Journal |
| issn | 1994-0416 1994-0424 |
| language | English |
| last_indexed | 2024-04-10T17:42:53Z |
| publishDate | 2023-02-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The Cryosphere |
| spelling | doaj.art-1b582d7b9a5d472b9f31c7cb50d41e082023-02-03T07:06:14ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242023-02-011745747610.5194/tc-17-457-2023Evolution of the dynamics, area, and ice production of the Amundsen Sea Polynya, Antarctica, 2016–2021G. J. Macdonald0G. J. Macdonald1S. F. Ackley2A. M. Mestas-Nuñez3A. Blanco-Cabanillas4NASA Center for Advanced Measurements in Extreme Environments (CAMEE), University of Texas at San Antonio, San Antonio, TX 78249, USAcurrently at: Department of Geography, University of Victoria, Victoria, BC V8W 2Y2, CanadaNASA Center for Advanced Measurements in Extreme Environments (CAMEE), University of Texas at San Antonio, San Antonio, TX 78249, USANASA Center for Advanced Measurements in Extreme Environments (CAMEE), University of Texas at San Antonio, San Antonio, TX 78249, USADepartment of Geography, University of Victoria, Victoria, BC V8W 2Y2, Canada<p>Polynyas are key sites of ice production during the winter and are important sites of biological activity and carbon sequestration during the summer. The Amundsen Sea Polynya (ASP) is the fourth largest Antarctic polynya, has recorded the highest primary productivity, and lies in an embayment of key oceanographic significance. However, knowledge of its dynamics, and of sub-annual variations in its area and ice production, is limited. In this study we primarily utilize Sentinel-1 synthetic aperture radar (SAR) imagery, sea ice concentration products, and climate reanalysis data, along with bathymetric data, to analyze the ASP over the period November 2016–March 2021. Specifically, we analyze (i) qualitative changes in the ASP's characteristics and dynamics, as well as quantitative changes in (ii) summer polynya area, and (iii) winter polynya area and ice production. From our analysis of SAR imagery we find that ice produced by the ASP becomes stuck in the vicinity of the polynya and sometimes flows back into the polynya, contributing to its closure and limiting further ice production. The polynya forms westward off a persistent chain of grounded icebergs that are located at the site of a bathymetric high. Grounded icebergs also influence the outflow of ice and facilitate the formation of a “secondary polynya” at times. Additionally, unlike some polynyas, ice produced by the polynya flows westward after formation, along the coast and into the neighboring sea sector. During the summer and early winter, broader regional sea ice conditions can play an important role in the polynya. The polynya opens in all summers, but record-low sea ice conditions in 2016/17 cause it to become part of the open ocean. During the winter, an average of 78 % of ice production occurs in April–May and September–October, but large polynya events often associated with high, southeasterly or easterly winds can cause ice production throughout the winter. While passive microwave data or daily sea ice concentration products remain key for analyzing variations in polynya area and ice production, we find that the ability to directly observe and qualitatively analyze the polynya at a high temporal and spatial resolution with Sentinel-1 imagery provides important insights about the behavior of the polynya that are not possible with those datasets.</p>https://tc.copernicus.org/articles/17/457/2023/tc-17-457-2023.pdf |
| spellingShingle | G. J. Macdonald G. J. Macdonald S. F. Ackley A. M. Mestas-Nuñez A. Blanco-Cabanillas Evolution of the dynamics, area, and ice production of the Amundsen Sea Polynya, Antarctica, 2016–2021 The Cryosphere |
| title | Evolution of the dynamics, area, and ice production of the Amundsen Sea Polynya, Antarctica, 2016–2021 |
| title_full | Evolution of the dynamics, area, and ice production of the Amundsen Sea Polynya, Antarctica, 2016–2021 |
| title_fullStr | Evolution of the dynamics, area, and ice production of the Amundsen Sea Polynya, Antarctica, 2016–2021 |
| title_full_unstemmed | Evolution of the dynamics, area, and ice production of the Amundsen Sea Polynya, Antarctica, 2016–2021 |
| title_short | Evolution of the dynamics, area, and ice production of the Amundsen Sea Polynya, Antarctica, 2016–2021 |
| title_sort | evolution of the dynamics area and ice production of the amundsen sea polynya antarctica 2016 2021 |
| url | https://tc.copernicus.org/articles/17/457/2023/tc-17-457-2023.pdf |
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