Institute of Marine Sciences, Italian National Research Council (ISMAR-CNR), Venice, 30122, Italy.
Univ. Brest, CNRS, IRD, Ifremer, Laboratoire d'Océanographie Physique et Spatiale (LOPS), IUEM, Plouzané, France.
Sci Rep. 2017 Aug 15;7(1):8276. doi: 10.1038/s41598-017-07704-9.
We consider the observation and analysis of oceanic rogue waves collected within spatio-temporal (ST) records of 3D wave fields. This class of records, allowing a sea surface region to be retrieved, is appropriate for the observation of rogue waves, which come up as a random phenomenon that can occur at any time and location of the sea surface. To verify this aspect, we used three stereo wave imaging systems to gather ST records of the sea surface elevation, which were collected in different sea conditions. The wave with the ST maximum elevation (happening to be larger than the rogue threshold 1.25H ) was then isolated within each record, along with its temporal profile. The rogue waves show similar profiles, in agreement with the theory of extreme wave groups. We analyze the rogue wave probability of occurrence, also in the context of ST extreme value distributions, and we conclude that rogue waves are more likely than previously reported; the key point is coming across them, in space as well as in time. The dependence of the rogue wave profile and likelihood on the sea state conditions is also investigated. Results may prove useful in predicting extreme wave occurrence probability and strength during oceanic storms.
我们考虑了在三维波场时空（ST）记录中收集的海洋反常波的观测和分析。这种记录方式可以获取海面区域，适合观察反常波，因为反常波是一种随机现象，可能随时在海面的任何位置发生。为了验证这一方面，我们使用了三个立体波成像系统来收集海面高度的 ST 记录，这些记录是在不同的海况下收集的。然后，我们在每个记录中隔离出具有 ST 最大高度（碰巧大于 1.25H 的反常波阈值）的波，以及它的时间分布。反常波显示出相似的分布，与极端波群理论一致。我们还在 ST 极值分布的背景下分析了反常波的发生概率，并得出了比之前报道的更高的反常波发生概率的结论；关键是要在空间和时间上遇到它们。还研究了反常波分布和可能性对海况条件的依赖性。这些结果可能有助于预测海洋风暴期间极端波的发生概率和强度。
