PenguinTracker / Glaciers / Jutulstraumen

Jutulstraumen

Outlet glacier · significant trend · measured 2013–2022

Jutulstraumen is flowing 5.3% slower than in 2013. Speed across 12 km² of grounded ice averaged 199 m/yr in 2022 — 0.5 metres a day — measured from satellite feature tracking over 10 usable years.

Measured speed by year (blue). The dashed line is the least-squares fit across every usable year — significant. Years whose coverage of the measured pixel set fell below 90% are dropped rather than interpolated, because feature tracking succeeds preferentially on fast crevassed ice and a sparse year is biased fast.

Grounded ice (solid) against its floating shelf (dashed), both indexed to 100 in 2013. Grounded -5.3% ± 3.4 · Shelf +4.0% ± 3.6, quoted as ±2 standard errors of the fitted slope. They are moving in opposite directions, and both slopes clear twice their own standard error. Averaging them into one figure for the glacier would report the difference as nothing. Every glacier compared this way →

Measured domaingrounded ice

Measured trunk12 km²

Years used10 of 23 in the archive

Period2013 – 2022

Speed in 2013212 m/yr

Speed in 2022199 m/yr

Floating shelf, same years+4.0% across 740 km²

Fitted change-5.3%

Fitted trend-1.2 m/yr² ± 0.4

Significancesignificant — slope is 3.1× its standard error

Mean coverage100% of the measured pixel set

Position71°30'S 0°30'E

What this number is, and is not

This is the speed of the ice surface, averaged over a fixed set of trunk pixels that carry valid data in every year reported. It is measured on grounded ice only. Grounded ice and floating shelf are separated using the masks the ITS_LIVE files carry, because they mean different things: grounded ice speeding up puts more ice across the grounding line, while a shelf that is already afloat displaces no extra water however fast it moves — and shelf speed jumps after a calving. Here the shelf changed +4.0% over the same years. The fitted change is quoted rather than the endpoint change (-5.9%), because an endpoint figure rides on two single noisy years.

Coverage before 1999 is negligible and no continent-wide acceleration figure is defensible from this product. Per-glacier series are only reported where the coverage gate is met. Each box is a fixed window around the trunk, not a drainage basin, so these are speeds over a measured area and not mass-balance figures.