Freak waves of different types in the coastal zone of the Baltic Sea

Abstract

Abstract. We present a statistical analysis of freak waves 1 measured during the 203 h of observation on sea surface elevation at a location in the coastal zone of the Baltic Sea (2.7 m depth) during June-July 2008. The dataset contains 97 freak waves occurring in both calm and stormy weather conditions. All of the freak waves are solitary waves, 63% of them having positive shape, 17.5% negative shape and 19.5% sign-variable shape. It is suggested that the freak waves can be divided into two groups. Those of the first group, which includes 92% of the freak waves, have an amplification factor (ratio of freak wave height to significant wave height) which does not vary from significant wave height and has values largely within the range of 2.0 to 2.4; while for the second group, which contain the most extreme freak waves, amplification factors depend strongly on significant wave height and can reach 3.1. Analysis based on the Generalised Pareto distribution is used to describe the waves of the first group and lends weight to the identification of the two groups. It is suggested that the probable mechanism of the generation of freak waves in the second group is dispersive focussing. The time-frequency spectra of the freak waves are studied and dispersive tracks, which can be interpreted as dispersive focussing, are demonstrated.

Outcomes of the Special Issue on Extreme and Rogue Waves

“…Didenkulova and Anderson (2010) presented a statistical analysis of freak waves measured in the coastal zone of the Baltic Sea (2.7 m in depth) during the period June-July 2008. The dataset lists 97 freak waves had occurred in calm and stormy weather conditions.…”

Wave climate in the Arkona Basin, the Baltic Sea

“…Such an increase would also make it easier to adequately represent the wave growth curves under low winds and after long-term calm situations (Soomere, 2005;Tuomi et al, 2011). The limitations of the waverider are apparently deeper and some other means such as, acoustical sensors (Didenkulova, 2011) or laser-based devices fixed to offshore platforms, should be used in order to properly resolve the short-wave domain.…”

Rogue waves in 2006–2010

“…He made an attempt to create a catalogue of rogue events in the coastal zone of Taiwan in the past 50 yr and reported 140 events. After that several more studies of rogue wave phenomenon in shallow waters followed (Cherneva et al, 2005;Didenkulova and Anderson, 2010;.…”