EGU22-892
https://doi.org/10.5194/egusphere-egu22-892
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

The impact of submesoscale fronts on turbulent air-sea heat fluxes in the Southern Ocean: Results from the first Saildrone circumnavigation of Antarctica

Hanna Rosenthal1, Louise C. Biddle1, Sebastiaan Swart1, Sarah T. Gille2, Matthew R. Mazloff2, and Marcel du Plessis1
Hanna Rosenthal et al.
  • 1University of Gothenburg, Marine Science, Gothenburg, Sweden
  • 2Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA.

The Southern Ocean is fundamental for our climate, accounting for 75% of the total oceanic heat uptake and absorbing 93% of excess heat arising from global warming. However, direct observations of air-sea heat fluxes are still scarce, particularly at small spatial and temporal scales. This study investigates the effect of fine-scale frontal activity (0.1 km–10 km) and sampling bias on measured turbulent heat fluxes in the Southern Ocean using high-resolution hydrographic and meteorological data collected by three autonomous surface vehicles (Saildrones) during their 2019 circumnavigation of Antarctica. We show that the uncertainty in observed air-sea heat fluxes increases with reduced sampling frequency. To have a  90% chance of capturing the mean turbulent heat flux within ±1 Wm2, the required sampling resolution is less than 30 km in summer and less than 10 km in winter. Surface temperature-driven density fronts were found to be numerous throughout the in situ datasets and ranged in length-scales from sub-kilometer to mesoscale (order of 0.1 km–100 km). The magnitude and variability of the turbulent heat flux gradient over these fronts tends to decrease with increasing frontal length, suggesting a strong coupling between heat fluxes and front size, thereby underscoring the need to capture fine-scale oceanographic features to better resolve air-sea fluxes of heat.

How to cite: Rosenthal, H., Biddle, L. C., Swart, S., Gille, S. T., Mazloff, M. R., and du Plessis, M.: The impact of submesoscale fronts on turbulent air-sea heat fluxes in the Southern Ocean: Results from the first Saildrone circumnavigation of Antarctica, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-892, https://doi.org/10.5194/egusphere-egu22-892, 2022.

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