Sea ice concentration is a quantitative geophysical parameter describing the fraction of a given ocean surface area covered by sea ice, typically expressed as a percentage or a unitless value between 0 and 1. It is derived from satellite remote sensing (e.g., passive microwave, SAR, optical sensors) or in situ observations using algorithms that discriminate ice from open water based on radiometric or spectral signatures. Sea ice concentration is fundamental for characterizing polar climate systems, validating sea-ice and coupled climate models, estimating surface heat and momentum fluxes, and supporting operational navigation, data assimilation, and reanalysis of cryospheric conditions.
Satellite observations have documented a pronounced decline in Antarctic sea ice extent since 2014, with especially sharp losses in recent years. Whether Antarctica's declining sea ice can recover hinges not only on how much ...
As I walked out onto the frozen Arctic water off Utqiagvik, Alaska, for the first time, I was mesmerized by the icescape.
Earth Sciences
Sep 18, 2025
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With the end of summer approaching in the Northern Hemisphere, the extent of sea ice in the Arctic shrank to its annual minimum on Sept. 10, according to NASA and the National Snow and Ice Data Center. The total sea ice coverage ...
Environment
Sep 18, 2025
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The Polarstern recently ended a two-month expedition in the central Arctic in Longyearbyen, Svalbard. The international and interdisciplinary research team, led by the Alfred Wegener Institute, focused on the summer melting ...
Earth Sciences
Sep 9, 2025
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NASA has a long record of monitoring Earth's sea surface height, information critical not only for tracking how the ocean changes over time but also for hurricane forecasting. These extreme storms can cost the United States ...
Earth Sciences
Aug 4, 2025
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On her first dedicated scientific voyage to Antarctica in March, the Australian icebreaker RSV Nuyina found the area sea-ice free. Scientists were able to reach places never sampled before.
Environment
Jul 1, 2025
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Antarctic sea ice is more than just a platform for penguins. The sea ice's high reflectivity influences the whole Earth's climate, and the ice is a key habitat for underwater as well as above-water ecosystems. Antarctic sea ...
Ecology
Jul 1, 2025
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New research has, for the first time, tracked ice shelf, sea ice and ocean swell wave conditions over multiple years in the lead-up to three large-scale iceberg "calving" events in Antarctica, revealing common patterns.
Earth Sciences
Jul 1, 2025
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The ocean around Antarctica is rapidly getting saltier at the same time as sea ice is retreating at a record pace. Since 2015, the frozen continent has lost sea ice similar to the size of Greenland. That ice hasn't returned, ...
Environment
Jul 1, 2025
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Researchers have discovered a dramatic and unexpected shift in the Southern Ocean, with surface water salinity rising and sea ice in steep decline.
Earth Sciences
Jun 30, 2025
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