Draupner Rogue Wave Physics T-Shirt

On 1 January 1995 a laser looking down from the Draupner platform caught the wave that proved rogue waves are real.

The Physics

The Draupner jacket is a steel platform in the Norwegian sector of the North Sea, in 70 m of water. A downward-looking laser wave sensor, sampling at 2.1 Hz, logged the sea surface. In the 20-minute record starting about 15:20 UTC, the significant wave height was about 12 m (11.92 m). One wave measured 25.6 m from trough to crest, with its crest about 18.5 m above still water.

H = 25.6 m > 2H_s (H_s = 11.9 m), η_c ≈ 18.5 m > 1.25 H_s

• H: wave height, trough to crest (m)
• η_c: crest height above still water level (m)
• H_s: significant wave height, H_s = 4σ_η (m)
• σ_η: standard deviation of surface elevation (m)

A wave counts as rogue if H/H_s > 2 or η_c/H_s > 1.25. Draupner did both: H/H_s = 2.15 and η_c/H_s = 1.55. The height alone was not unheard of (the 100-year design wave height was about 27 m); what surprised engineers was so tall a crest in a 12 m sea.

Honest caveat: Why it formed is still debated. Proposed explanations include a crossing sea and nonlinear focusing, and some researchers treat such waves as a matter of probability. It is the most famous rogue wave recorded by an instrument, but not necessarily the first.

Sources

• S. Haver, "A possible freak wave event measured at the Draupner jacket January 1 1995," Rogue Waves 2004 workshop, Brest.
• D. A. G. Walker, P. H. Taylor, R. Eatock Taylor, Appl. Ocean Res. 26, 73–83 (2004).
• T. A. A. Adcock et al., "Did the Draupner wave occur in a crossing sea?" Proc. R. Soc. A 467, 3004–3021 (2011).
• K. Dysthe, H. E. Krogstad, P. Müller, "Oceanic rogue waves," Annu. Rev. Fluid Mech. 40, 287–310 (2008).
• L. Cavaleri et al., "The Draupner Event," Bull. Am. Meteorol. Soc. 98, 729–735 (2017).
• J.-R. Bidlot et al., "What conditions led to the Draupner freak wave?" ECMWF Newsletter 148 (2016).

On the shirt

Back: "DRAUPNER · 1 JAN 1995 — THE WAVE THAT PROVED ROGUE WAVES ARE REAL", with H = 25.6 m > 2H_s (H_s = 11.9 m), η_c ≈ 18.5 m > 1.25 H_s, H_s = 4σ_η, the ratios 2.15 and 1.55, and "DRAUPNER PLATFORM · NORTH SEA · ABOUT 15:20 UTC". Printed front and back on a unisex tee.