Articles | Volume 19, issue 9
https://doi.org/10.5194/tc-19-3535-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-19-3535-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
05 Sep 2025
Research article |
| 05 Sep 2025
| 05 Sep 2025
Southern Ocean sea-ice leads: first insights into regional lead patterns, seasonality, and trends, 2003–2023
Department of Environmental Meteorology, Trier University, Trier, Germany
Department of Environmental Meteorology, Trier University, Trier, Germany
Günther Heinemann
Department of Environmental Meteorology, Trier University, Trier, Germany
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This preprint is open for discussion and under review for The Cryosphere (TC).
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Cracks and openings in sea ice, called leads, play an important role in regulating heat exchange between the ocean and atmosphere, affecting global climate patterns. This study used a machine learning model trained on wintertime data from 2003 to 2023 to identify the key drivers of leads across the Southern Ocean and sub-regions. The analysis shows that 2m air temperature, wind-ice divergence, and ocean currents are the primary drivers, though their importance differs across regions and seasons.
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Cracks and openings in sea ice, called leads, play an important role in regulating heat exchange between the ocean and atmosphere, affecting global climate patterns. This study used a machine learning model trained on wintertime data from 2003 to 2023 to identify the key drivers of leads across the Southern Ocean and sub-regions. The analysis shows that 2m air temperature, wind-ice divergence, and ocean currents are the primary drivers, though their importance differs across regions and seasons.
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Leads (openings in sea ice cover) are created by sea ice dynamics. Because they are important for many processes in the Arctic winter climate, we aim to detect them with satellites. We present two new techniques to detect lead widths of a few hundred meters at high spatial resolution (700 m) and independent of clouds or sun illumination. We use the MOSAiC drift 2019–2020 in the Arctic for our case study and compare our new products to other existing lead products.
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In the southern Weddell Sea, the strong sea ice growth in coastal polynyas drives formation of dense shelf water. By using a sea ice–ice shelf–ocean model with representation of the changing icescape based on satellite data, we find that polynya sea ice growth depends on both the regional atmospheric forcing and the icescape. Not just strength but also location of the sea ice growth in polynyas affects properties of the dense shelf water and the basal melting of the Filchner–Ronne Ice Shelf.
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Sea ice is an important constituent of the global climate system. We here use satellite data to identify regions in the Arctic where the sea ice breaks up in so-called leads (i.e., linear cracks) regularly during winter. This information is important because leads determine, e.g., how much heat is exchanged between the ocean and the atmosphere. We here provide first insights into the reasons for the observed patterns in sea-ice leads and their relation to ocean currents and winds.
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We use satellite data records collected along the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) drift to categorize ice conditions that shaped and characterized the floe and surroundings during the expedition. A comparison with previous years is made whenever possible. The aim of this analysis is to provide a basis and reference for subsequent research in the six main research areas of atmosphere, ocean, sea ice, biogeochemistry, remote sensing and ecology.
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Short summary
Sea-ice leads facilitate the exchange of heat and moisture between the ocean and the atmosphere during wintertime. We present a new dataset on monthly wintertime sea-ice leads in the Southern Ocean from 2003 to 2023. Our study reveals distinct regional patterns, seasonal variability, and small but significant trends. Here, we present initial findings on Southern Ocean lead dynamics to support future research into the complex pan-Antarctic interactions among sea ice, ocean, and atmosphere.
Sea-ice leads facilitate the exchange of heat and moisture between the ocean and the atmosphere...
