wave height · International waters
Rockall Trough, North Atlantic
Winter mean significant wave height
Modelled demonstration series · not observed data
Nobody lives here, so the population column reads zero, and that is misleading. This water is crossed by most of the shipping between Europe and North America, and significant wave height is the number that decides whether a route is taken or a crossing is delayed. Its trend also sets the design load for every offshore structure downwind.
75 years, modelled
Same reading, two normals
| Normal | Mean | σ | Pct | Return |
|---|---|---|---|---|
| 1951–1980 | 4.30 m | +1.30σ | 90th | 1 in 10 years |
| 1991–2020 | 4.45 m | +1.03σ | 85th | 1 in 6.6 years |
Today would rank 11 of 76 for highest value in the modelled series. Nothing about the reading changes between rows — only the yardstick.
The season here
The North Atlantic in winter has the longest sustained fetch of any ocean basin in the northern hemisphere. Nothing stops the swell before Ireland.
Where this series comes from
MODELLED SERIES — not observed. Parameters set from published North Atlantic winter significant-wave-height climatology. The 75 annual values are synthesised by the seeded generator. Significant wave height is the mean height of the highest third of waves — individual waves regularly exceed it substantially.
Every number on this page comes from a modelled series: 75 annual values synthesised by a seeded generator from published climatological parameters for Rockall Trough, North Atlantic. It shows how anomaly reasoning works. It is not a measurement and must not be cited as one.
How to read σ
σ counts standard deviations from this place's own normal. The sigma guide · return periods.
More wave height stations
Open Rockall Trough on the field →