A contrast in sea ice drift and deformation between winter and spring of 2019 in the Antarctic marginal ice zone

Womack, Ashleigh, Alberello, Alberto ORCID: https://orcid.org/0000-0001-7957-4012, de Vos, Marc, Toffoli, Alessandro, Verrinder, Robyn and Vichi, Marcello (2024) A contrast in sea ice drift and deformation between winter and spring of 2019 in the Antarctic marginal ice zone. The Cryosphere, 18 (1). pp. 205-229. ISSN 1994-0440

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Two ensembles of buoys, deployed in the marginal ice zone (MIZ) of the north-eastern Weddell Sea region of the Southern Ocean, are analysed to characterise the dynamics driving sea ice drift and deformation during the winter-growth and the spring-retreat seasons of 2019. The results show that although the two buoy arrays were deployed within the same region of ice-covered ocean, their trajectory patterns were vastly different. This indicates a varied response of sea ice in each season to the local winds and currents. Analyses of the winter data showed that the Antarctic Circumpolar Current modulated the drift near the sea ice edge. This led to a highly energetic and mobile ice cover, characterised by free-drift conditions. The resulting drift and deformation were primarily driven by large-scale atmospheric forcing, with negligible contributions due to the wind-forced inertial response. For this highly advective coupled ice–ocean system, ice drift and deformation linearly depended on atmospheric forcing. We also highlight the limits of commercial floating ice velocity profilers in this regime since they may bias the estimates of sea ice drift and the ice type detection. On the other hand, the spring drift was governed by the inertial response as increased air temperatures caused the ice cover to melt and break up, promoting a counterintuitively less wind-driven ice–ocean system that was more dominated by inertial oscillations. In fact, the deformation spectra indicate a strong decoupling to large-scale atmospheric forcing. Further analyses, extended to include the deformation datasets from different regions around Antarctica, indicate that, for similar spatial scales, the magnitude of deformation varies between seasons, regions, and the proximity to the sea ice edge and the coastline. This implies the need to develop rheology descriptions that are aware of the ice types in the different regions and seasons to better represent sea ice dynamics in the MIZ.

Item Type: Article
Additional Information: Acknowledgements: This expedition has been supported by the National Research Foundation of South Africa (grant no. 118745) through the South African National Antarctic Programme. This work has received funding from the European Union's Horizon 2020 Research and Innovation programme under grant agreement no. 101003826 via project CRiceS (Climate Relevant interactions and feedbacks: the key role of sea ice and Snow in the polar and global climate system). Alessandro Toffoli acknowledges support from the Australian Research Council (grant no. DP200102828). Alberto Alberello acknowledges the support from the London Mathematical Society (Scheme 5 – Ref. 52206). The authors would like to thank the South African Weather Service (SAWS) for the usage of the ISVP data. We acknowledge the Southern oCean seAsonaL Experiment (SCALE) and thank the captain and the crew of the S.A. Agulhas II for their assistance during the deployments. Code and data availability: This study makes use of various datasets with different availabilities. The ERA5 reanalysis product at single levels is available at https://doi.org/10.24381/cds.adbb2d47 (Copernicus Climate Change Service (C3S), 2017; Hersbach et al., 2023). The GlobCurrent database is available at https://marine.copernicus.eu/ (last access: 7 June 2023; DOI: https://doi.org/10.48670/moi-00050, Copernicus Marine Service Information (CMEMS), 2014). The sea ice concentration data were obtained from the passive microwave Advanced Microwave Scanning Radiometer 2 (AMSR2) sensor (Spreen et al., 2008) at ftp://ftp-projects.cen.uni-hamburg.de/seaice/AMS2/ (last access: 2 October 2021). SIC data have also been obtained from the Special Sensor Microwave Imager/-Sounder (SSMIS) product (Cavalieri et al., 1996); however, the former URL (https://data.marine.copernicus.eu/products (Copernicus Marine Service Information (CMEMS), 2014; last access: 3 October 2021) has expired, and the data can now be found at https://cds.climate.copernicus.eu/cdsapp#!/dataset/satellite-seaice-concentration?tab=overview (Copernicus Climate Change Service (C3S), 2017; last access: 8 May 2023). The in situ ISVP data are available at https://doi.org/10.5281/zenodo.7954779 (de Vos et al., 2023). The in situ Trident data are available at https://doi.org/10.5281/zenodo.7954841 (Womack et al., 2023). The code used to process the data and produce the figures is available at https://github.com/mvichi/antarctic-buoys/ (last access: 5 May 2023; DOI: https://doi.org/10.25375/uct.24850146, Womack and Vichi, 2023).
Uncontrolled Keywords: sdg 14 - life below water ,/dk/atira/pure/sustainabledevelopmentgoals/life_below_water
Faculty \ School: Faculty of Science > School of Mathematics
UEA Research Groups: Faculty of Science > Research Groups > Fluid and Solid Mechanics
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Depositing User: LivePure Connector
Date Deposited: 12 Jan 2024 01:41
Last Modified: 15 Jan 2024 01:34
URI: https://ueaeprints.uea.ac.uk/id/eprint/94153
DOI: 10.5194/tc-18-205-2024

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