Field Site Seminar, Mika Malila: Extreme wave characteristics from high-resolution space-time field observations

Zoom webinar ID:969 1093 3469

UNC Institute of Marine Sciences

Abstract:

Extreme sea-surface gravity waves, frequently referred to as rogue waves, pose threats to offshore platforms and shipping due to the difficulties in predicting where and when they will occur. The predictions are made more uncertain by the relatively small amount of direct, verifiable observations of extreme individual waves in open-ocean storm conditions. In this talk I will present work I that did during my PhD at the Norwegian Meteorological Institute on laser altimeter and stereo video observations of offshore extreme waves off a platform in the central North Sea. The field data allow us to identify sea states that lead to wave crest height distributions that deviate the most from widely used theoretical distributions. Moreover, sea-surface reconstructions from the stereo video system show that extreme wave crests momentarily slow down at the moment of wave group focus. This finding is of importance for estimates of wave loads caused by both breaking and non-breaking extreme waves, as well as for parameterizations of wave energy dissipation in numerical models.

Host: Johanna Rosman