Findings and research questions
Each finding is a sentence from a published Heimdall Research table, with the row behind the number and the question it answers. A version that is still in preparation stays off this page until the catalog marks it published. This page lists 5 findings.
Dataset · 5 findings
Arctic Open-Water Window
Not for navigation. Use at your own risk. Provided as is, without warranty of any kind.
Trends
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At Vilkitsky Strait, mean open days at the 15 percent ice cutoff rose from 7.9 days a year in 1979-1988 to 82.6 days in 2016-2025 (difference +74.7 days).
Vilkitsky Strait connects the Kara and Laptev seas on the Northern Sea Route.
Breakdown
The published seasons table covers three gates. For Vilkitsky Strait (nsr-vilkitsky), the mean of open_days_15 on full seasons is 7.9 in 1979-1988 and 82.6 in 2016-2025. That is a rise of 74.7 days between those decade windows. An open day here is a day when average sea-ice concentration inside the gate polygon sits below the 15 percent cutoff, the strictest of the three cutoffs in the release.
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At Bering Strait, mean open days at the 15 percent cutoff rose from 140.4 days a year in 1979-1988 to 196.5 days in 2016-2025 (difference +56.1 days).
Bering Strait timing matters for communities and seasonal operations on the Pacific-Arctic passage.
Breakdown
For bering-strait, mean open_days_15 on full seasons is 140.4 in 1979-1988 and 196.5 in 2016-2025. The difference is +56.1 days. In the latest decade, Bering Strait still has the longest mean open season of the three published gates.
Places
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Over 47 full seasons (1979-2025), Bering Strait had a median of 172 open days at the 15 percent cutoff (range 104 to 234).
If you need a typical year from this package, quote the median.
Breakdown
Across 47 non-partial seasons from 1979 through 2025, the median of open_days_15 for bering-strait is 172. The shortest of those seasons has 104 open days and the longest has 234. The median is the middle season once the kept seasons are ordered from shortest to longest.
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At the Barrow gate, mean open days at the 15 percent cutoff rose from 10.5 days a year in 1979-1988 to 51.3 days in 2016-2025 (difference +40.8 days).
The Barrow gate sits on Alaska's north coast seasonal open water.
Breakdown
For nwp-barrow, mean open_days_15 is 10.5 in 1979-1988 and 51.3 in 2016-2025. The difference is +40.8 days. Among the three published gates, Barrow has the shortest mean open season in 2016-2025.
Extremes
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Vilkitsky Strait had 8 seasons with zero open days in 1979-1988 and 0 such seasons in 2016-2025.
If you need both presence and length, read this with the Vilkitsky decade-mean finding.
Breakdown
In 1979-1988, 8 full seasons at nsr-vilkitsky have open_days_15 equal to zero. In 2016-2025, that count is 0. The gate still varies in how long it stays open; what changed here is whether any full season stayed at zero.
Dataset · 0 findings
Storm Blackout and Restoration
Estimates from public records and satellite night light. Not for real-time emergency response or for any decision about one address or property.
Dataset · 0 findings
Western Terminal Lakes
Not for water-rights, legal or engineering decisions.
Provided as is, without warranty of any kind.