Rogue Waves in the Ocean, the Role
of Modulational Instability, and Abrupt
Changes of Environmental Conditions
that Can Provoke Non Equilibrium Wave
Dynamics
Karsten Trulsen
Dedicated to Eugene G. Morozov on his 70th Birthday
Introduction
Rogue or freak waves are waves that are unexpectedly large in comparison with ambient waves. The term “freak wave” was apparently introduced by Draper [16] who
discussed ship accidents that could have been provoked by such waves. Mallory [32]
discussed serious consequences of extreme waves on ship traffic in the Agulhas current off South Africa. With the advent of offshore oil and gas exploration, well documented observations of freak waves accumulated (e.g. Sand et al. [48]). The “New
Year” wave at Draupner in the North Sea 1/1–1995 is one of the best documented
observations of a rogue wave [8, 25]. Later the even more extreme Andrea wave at
Ekofisk in the North Sea 9/11–2007 was also well documented [7, 15, 31].
This is a good opportunity to give praise to the policy of openness demonstrated
by the Norwegian oil company Statoil giving academic researchers unrestricted
access to the Draupner “New Year” wave dataset. Few measured time series have
been published more often, or inspired more wave research, than the one shown in
Fig. 1.
There is currently no consensus on how to define rogue or freak waves. Common
criteria are H∕H s > 2 or í µí¼ c ∕H s > 1.25 where H is the zero-crossing wave height, í µí¼ c
is the crest height, and H s is the significant wave height defined as four times the
standard deviation of the surface elevation typically calculated from a 20 min time
series [17, 24].
K. Trulsen ( ✉ )
Department of Mathematics, University of Oslo, Oslo, Norway
e-mail: karstent@math.uio.no
© Springer International Publishing AG, part of Springer Nature 2018
M. G. Velarde et al. (eds.), The Ocean in Motion, Springer Oceanography,
https://doi.org/10.1007/978-3-319-71934-4_17
239
of Modulational Instability, and Abrupt
Changes of Environmental Conditions
that Can Provoke Non Equilibrium Wave
Dynamics
Karsten Trulsen
Dedicated to Eugene G. Morozov on his 70th Birthday
Introduction
Rogue or freak waves are waves that are unexpectedly large in comparison with ambient waves. The term “freak wave” was apparently introduced by Draper [16] who
discussed ship accidents that could have been provoked by such waves. Mallory [32]
discussed serious consequences of extreme waves on ship traffic in the Agulhas current off South Africa. With the advent of offshore oil and gas exploration, well documented observations of freak waves accumulated (e.g. Sand et al. [48]). The “New
Year” wave at Draupner in the North Sea 1/1–1995 is one of the best documented
observations of a rogue wave [8, 25]. Later the even more extreme Andrea wave at
Ekofisk in the North Sea 9/11–2007 was also well documented [7, 15, 31].
This is a good opportunity to give praise to the policy of openness demonstrated
by the Norwegian oil company Statoil giving academic researchers unrestricted
access to the Draupner “New Year” wave dataset. Few measured time series have
been published more often, or inspired more wave research, than the one shown in
Fig. 1.
There is currently no consensus on how to define rogue or freak waves. Common
criteria are H∕H s > 2 or í µí¼ c ∕H s > 1.25 where H is the zero-crossing wave height, í µí¼ c
is the crest height, and H s is the significant wave height defined as four times the
standard deviation of the surface elevation typically calculated from a 20 min time
series [17, 24].
K. Trulsen ( ✉ )
Department of Mathematics, University of Oslo, Oslo, Norway
e-mail: karstent@math.uio.no
© Springer International Publishing AG, part of Springer Nature 2018
M. G. Velarde et al. (eds.), The Ocean in Motion, Springer Oceanography,
https://doi.org/10.1007/978-3-319-71934-4_17
239