Turbulent heat flux dynamics along the Dotson and Getz ice-shelf fronts (Amundsen Sea, Antarctica)
<p>In coastal polynyas, where sea-ice formation and melting occur, it is crucial to have accurate estimates of heat fluxes in order to predict future sea-ice dynamics. The Amundsen Sea Polynya is a coastal polynya in Antarctica that remains poorly observed by in situ observations because of it...
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Copernicus Publications
2025-02-01
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| Series: | Ocean Science |
| Online Access: | https://os.copernicus.org/articles/21/359/2025/os-21-359-2025.pdf |
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| author | B. Jacob B. Y. Queste M. D. du Plessis |
| author_facet | B. Jacob B. Y. Queste M. D. du Plessis |
| author_sort | B. Jacob |
| collection | DOAJ |
| description | <p>In coastal polynyas, where sea-ice formation and melting occur, it is crucial to have accurate estimates of heat fluxes in order to predict future sea-ice dynamics. The Amundsen Sea Polynya is a coastal polynya in Antarctica that remains poorly observed by in situ observations because of its remoteness. Consequently, we rely on models and reanalysis that are un-validated against observations to study the effect of atmospheric forcing on polynya dynamics. We use austral summer 2022 shipboard data to understand the turbulent heat flux dynamics in the Amundsen Sea Polynya and evaluate our ability to represent these dynamics in ERA5. We show that cold- and dry-air outbreaks from Antarctica enhance air–sea temperature and humidity gradients, triggering episodic heat loss events. The ocean heat loss is larger along the ice-shelf front, and it is also where the ERA5 turbulent heat flux exhibits the largest biases, underestimating the flux by up to 141 W m<span class="inline-formula"><sup>−2</sup></span> due to its coarse resolution. By reconstructing a turbulent heat flux product from ERA5 variables using a nearest-neighbor approach to obtain sea surface temperature, we decrease the bias to 107 W m<span class="inline-formula"><sup>−2</sup></span>. Using a 1D model, we show that the mean co-located ERA5 heat loss underestimation of 28 W m<span class="inline-formula"><sup>−2</sup></span> led to an overestimation of the summer evolution of sea surface temperature (heat content) by <span class="inline-formula">+</span>0.76 °C (<span class="inline-formula">+</span>8.2<span class="inline-formula">×</span>10<span class="inline-formula"><sup>7</sup></span> J) over 35 d. By obtaining the reconstructed flux, the reduced heat loss bias (12 W m<span class="inline-formula"><sup>−2</sup></span>) reduced the seasonal bias in sea surface temperature (heat content) to <span class="inline-formula">−</span>0.17 °C (<span class="inline-formula">−</span>3.30 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>7</sup></span> J) over the 35 d. This study shows that caution should be applied when retrieving ERA5 turbulent flux along the ice shelves and that a reconstructed flux using ERA5 variables shows better accuracy.</p> |
| format | Article |
| id | doaj-art-231fd818ab044d84b6fb0baa8f424643 |
| institution | Kabale University |
| issn | 1812-0784 1812-0792 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | Copernicus Publications |
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| series | Ocean Science |
| spelling | doaj-art-231fd818ab044d84b6fb0baa8f4246432025-02-07T11:38:20ZengCopernicus PublicationsOcean Science1812-07841812-07922025-02-012135937910.5194/os-21-359-2025Turbulent heat flux dynamics along the Dotson and Getz ice-shelf fronts (Amundsen Sea, Antarctica)B. Jacob0B. Y. Queste1M. D. du Plessis2Department of Marine Sciences, University of Gothenburg, Gothenburg, SwedenDepartment of Marine Sciences, University of Gothenburg, Gothenburg, SwedenDepartment of Marine Sciences, University of Gothenburg, Gothenburg, Sweden<p>In coastal polynyas, where sea-ice formation and melting occur, it is crucial to have accurate estimates of heat fluxes in order to predict future sea-ice dynamics. The Amundsen Sea Polynya is a coastal polynya in Antarctica that remains poorly observed by in situ observations because of its remoteness. Consequently, we rely on models and reanalysis that are un-validated against observations to study the effect of atmospheric forcing on polynya dynamics. We use austral summer 2022 shipboard data to understand the turbulent heat flux dynamics in the Amundsen Sea Polynya and evaluate our ability to represent these dynamics in ERA5. We show that cold- and dry-air outbreaks from Antarctica enhance air–sea temperature and humidity gradients, triggering episodic heat loss events. The ocean heat loss is larger along the ice-shelf front, and it is also where the ERA5 turbulent heat flux exhibits the largest biases, underestimating the flux by up to 141 W m<span class="inline-formula"><sup>−2</sup></span> due to its coarse resolution. By reconstructing a turbulent heat flux product from ERA5 variables using a nearest-neighbor approach to obtain sea surface temperature, we decrease the bias to 107 W m<span class="inline-formula"><sup>−2</sup></span>. Using a 1D model, we show that the mean co-located ERA5 heat loss underestimation of 28 W m<span class="inline-formula"><sup>−2</sup></span> led to an overestimation of the summer evolution of sea surface temperature (heat content) by <span class="inline-formula">+</span>0.76 °C (<span class="inline-formula">+</span>8.2<span class="inline-formula">×</span>10<span class="inline-formula"><sup>7</sup></span> J) over 35 d. By obtaining the reconstructed flux, the reduced heat loss bias (12 W m<span class="inline-formula"><sup>−2</sup></span>) reduced the seasonal bias in sea surface temperature (heat content) to <span class="inline-formula">−</span>0.17 °C (<span class="inline-formula">−</span>3.30 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>7</sup></span> J) over the 35 d. This study shows that caution should be applied when retrieving ERA5 turbulent flux along the ice shelves and that a reconstructed flux using ERA5 variables shows better accuracy.</p>https://os.copernicus.org/articles/21/359/2025/os-21-359-2025.pdf |
| spellingShingle | B. Jacob B. Y. Queste M. D. du Plessis Turbulent heat flux dynamics along the Dotson and Getz ice-shelf fronts (Amundsen Sea, Antarctica) Ocean Science |
| title | Turbulent heat flux dynamics along the Dotson and Getz ice-shelf fronts (Amundsen Sea, Antarctica) |
| title_full | Turbulent heat flux dynamics along the Dotson and Getz ice-shelf fronts (Amundsen Sea, Antarctica) |
| title_fullStr | Turbulent heat flux dynamics along the Dotson and Getz ice-shelf fronts (Amundsen Sea, Antarctica) |
| title_full_unstemmed | Turbulent heat flux dynamics along the Dotson and Getz ice-shelf fronts (Amundsen Sea, Antarctica) |
| title_short | Turbulent heat flux dynamics along the Dotson and Getz ice-shelf fronts (Amundsen Sea, Antarctica) |
| title_sort | turbulent heat flux dynamics along the dotson and getz ice shelf fronts amundsen sea antarctica |
| url | https://os.copernicus.org/articles/21/359/2025/os-21-359-2025.pdf |
| work_keys_str_mv | AT bjacob turbulentheatfluxdynamicsalongthedotsonandgetziceshelffrontsamundsenseaantarctica AT byqueste turbulentheatfluxdynamicsalongthedotsonandgetziceshelffrontsamundsenseaantarctica AT mdduplessis turbulentheatfluxdynamicsalongthedotsonandgetziceshelffrontsamundsenseaantarctica |