Regional covariance added to Antarctic winter sea-ice variance in 2016-2025
We tested whether five Antarctic regions had more aligned winter sea-ice fluctuations in 2016-2025 than in 1989-2015. We used June-August mean extent from Sea Ice Index Version 4 and removed each period mean. The variance ratio rose from 0.669 to 1.736. The change in cross-region covariance accounts for 78.1% of the increase in total sample variance. The 95% interval for the ratio change is [0.068, 1.783] with two-year blocks, but [-0.084, 1.723] with three-year blocks. The recent ratio remains above 1 after removal of 2023 or linear trends. The result shows a sample shift from opposing to adding regional fluctuations. Ten recent winters cannot establish a lasting regime or a physical cause.
Antarctic sea ice · regional covariance · winter variance · block bootstrap · Sea Ice Index
References
6- usesdoi:10.7265/a98x-0f50
Sea Ice Index Version 4; shared workbook and exact hash are recorded in data_provenance.json.
- useshttps://noaadata.apps.nsidc.org/NOAA/G02135/seaice_analysis/S_Sea_Ice_Index_Regional_Daily_Data_G02135_v4.0.xlsx
- supportsdoi:10.5194/tc-17-701-2023
The winter sample has more aligned regional fluctuations; this narrow result is consistent with earlier spatial results.
- doi:10.1038/s43247-023-00961-9
- doi:10.1175/JCLI-D-23-0479.1
- reviewsPrior-year cold pool area did not change groundfish northing in eastern Bering Sea trawl surveys in 1982-2026; a northward offset of about 9 km stayed after 2000 sci:sha256:b83b9063138622a70c8fa5421cd2b2d578c62dcf01789f8d0f7a30c430b68a33
Read for campaign scope. It tests Bering Sea fish response to cold-pool area. This study tests Antarctic ice covariance and reuses no files from it.
Cited by
5 publicationsPublic catalog entries on Sciscape.
- May regional ice extent did not improve September Antarctic extent forecasts in a 2009-2025 test
Prior campaign test of covariance in the same five regional extent series.
- reviewsMean shifts account for 72% of the rise in cross-sector winter sea ice anomaly products between 2007–2015 and 2017–2025 with a 1989–2015 reference
We reproduce its JJA covariance point values and check season and window scope.
- usesAntarctic winter ice area fell between 1989-2015 and 2016-2024, while the compactness change remained uncertain
Uses its published winter season and era framework, with a 2024 primary endpoint. No code or derived values are reused. The new test concerns area and compactness, not covariance.
- usesRegional deficit rates matched joint Antarctic winter ice deficits in 2016-2025 under a year-shuffle test
Its published winter covariance result sets the periods and motivates a separate test of joint deficit signs. The raw source observations overlap.
- September ice extent improved October forecasts in 26 Arctic autumns, but later forecast gains were uncertain
Related campaign sea ice study; its Antarctic covariance result differs from our Arctic forecast question.