Preprints
https://doi.org/10.5194/egusphere-2024-2076
https://doi.org/10.5194/egusphere-2024-2076
17 Jul 2024
 | 17 Jul 2024

Turbulent heat flux dynamics along the Dotson and Getz ice-shelf fronts (Amundsen Sea, Antarctica)

Blandine Jacob, Bastien Y. Queste, and Marcel D. du Plessis

Abstract. In coastal polynyas, where sea–ice formation occurs, it is crucial to have accurate estimates of heat fluxes in order to predict future rates of sea–ice formation. The Amundsen Sea Polynya is the fourth largest coastal polynya around Antarctica, yet remains poorly observed because of its remoteness. Consequently, we rely on models and reanalysis that are unvalidated to study the effect of atmospheric forcing on polynya dynamics. We use summer ship-board data from the NBP22/02 cruise 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 heat loss is larger along the ice shelves, and it is also where the ERA5 turbulent heat flux exhibits the largest biases, underestimating the flux by up to 141 W m-2 due to its coarse resolution and misrepresentation of ice-shelf location. By reconstructing a turbulent heat flux product from ERA5 variables using a nearest neighbour approach to obtain sea surface temperature, we decrease the bias to 107 W m-2. Using a 1D-model, we show that the mean co-located ERA5 heat loss underestimation of -28 W m-2 led to an overestimation of the summer evolution of sea surface temperature (heat content) by +0.76 °C (+8.2×107 J) over 35-days. By obtaining the reconstructed flux, the reduced heat loss bias (12 W m-2) reduced the seasonal bias in sea surface temperature (heat content) to -0.17 °C (-3.30×107 J) over the 35–days. 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.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Share

Journal article(s) based on this preprint

07 Feb 2025
| Highlight paper
Turbulent heat flux dynamics along the Dotson and Getz ice-shelf fronts (Amundsen Sea, Antarctica)
Blandine Jacob, Bastien Y. Queste, and Marcel D. du Plessis
Ocean Sci., 21, 359–379, https://doi.org/10.5194/os-21-359-2025,https://doi.org/10.5194/os-21-359-2025, 2025
Short summary Co-editor-in-chief
Download

The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

This is the first in-situ validation of the reanalysis atmospheric flux and observations. Given...
Short summary
Few observations exist in the Amundsen Sea. Consequently, studies rely on models (e.g. ERA5) to...
Share