High-resolution thermal imaging in the Antarctic marginal ice zone: Skin temperature heterogeneity and effects on heat fluxes

Tersigni, Ippolita, Alberello, Alberto ORCID: https://orcid.org/0000-0001-7957-4012, Messori, Gabriele, Vichi, Marcello, Onorato, Miguel and Toffoli, Alessandro (2023) High-resolution thermal imaging in the Antarctic marginal ice zone: Skin temperature heterogeneity and effects on heat fluxes.

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Insufficient in-situ observations from the Antarctic marginal ice zone limit our understanding and description of relevant mechanical and thermodynamic processes that regulate the seasonal sea ice cycle. Here we present high-resolution thermal images of the ocean surface and complementary measurements of atmospheric variables that were acquired underway during one austral winter and one austral spring expedition in the Atlantic and Indian sectors of the Southern Ocean. Skin temperature data and ice cover images were used to estimate the partitioning of the heterogeneous surface and calculate the heat fluxes to compare with ERA5 reanalyses. The winter marginal ice zone was composed of different but relatively regularly distributed sea ice types with sharp thermal gradients. The surface-weighted skin temperature compared well with the reanalyses due to a compensation of errors between the sea ice fraction and the ice floe temperature. These uncertainties determine the dominant source of inaccuracy for heat fluxes as computed from observed variables. In spring, the sea ice type distribution was more irregular, with alternation of sea ice cover and large open water fractions even 400 km from the ice edge. The skin temperature distribution was more homogeneous and did not produce substantial uncertainties in heat fluxes. The discrepancies relative to reanalysis data are however larger than in winter and are attributed to biases in the atmospheric variables, with the downward solar radiation being the most critical.

Item Type: Article
Additional Information: Author Acknowledgments: The expeditions were funded by the South African National Antarctic Programme through the National Research Foundation. AA and AT were funded by the ACE Foundation and Ferring Pharmaceuticals and the Australian Antarctic Science Program (project 4434). AA acknowledges support from the Japanese Society for the Promotion of Science (PE19055) and the London Mathematical Society (Scheme 5 – 52206). AT acknowledges support from the Australia Research Council (DP200102828). MV was supported by the NRF SANAP contract UID118745. GM acknowledges support from the Swedish Foundation for International Cooperation in Research and Higher Education (project no. SA2017-7063). IT and AT thank Dr J. Bidlot (ECMWF) and Dr L. Aouf (Meteo France) for support with the ERA5 products. We are indebted to Captain Knowledge Bengu and the crew of the SA Agulhas II for their invaluable contribution to data collection We acknowlddge Dr L. Fascette for technical support.
Faculty \ School: Faculty of Science > School of Mathematics
UEA Research Groups: Faculty of Science > Research Groups > Fluid and Solid Mechanics
Depositing User: LivePure Connector
Date Deposited: 13 Jul 2023 15:31
Last Modified: 13 Jul 2023 15:31
URI: https://ueaeprints.uea.ac.uk/id/eprint/92605
DOI: 10.22541/essoar.168500257.79644507/v1

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