Crazy dog ​​waves on the sea

  For a long time, the mad dog wave was just a legend of sailors. It was only in the last few decades that the existence of this mysterious sea “behemoth” was “real hammer”.
  During the New Year’s Day in 1995, a high-resolution snapshot captured a sudden 26-meter-high wave standing on the sea. This “behemoth” attacked Dropnil in the North Sea of ​​Norway with lightning speed. The petroleum equipment system has given the local people a heads-up to those who are immersed in the festive atmosphere. This “behemoth” is a crazy dog ​​wave. Since then, researchers have determined that in the second half of the 20th century alone, more than 20 cargo ships were taken away by mad dogs and more than 500 people were killed.
  The appearance of the giant waves of Dlopnier stimulated physicists, who determined to find out how these giants formed. After long-term research, the scientific community has produced two schools of thought about the evolution of mad dog waves. One view is that waves are superimposed, that is, a group of rising waves move forward at different speeds, that is, several independent waves propagate at different speeds, but the components of the waves always play an independent role. At a certain moment, A large number of waves happen to overlap to produce mad dog waves; another view is that the way waves interact is more complicated. They can interact and the energy between them can also be transformed into each other. These interactions can work together to produce mad dog waves. The former is linear addition, and the latter is nonlinear focusing.
  In reality, these two explanations are reasonable. However, although linear addition can explain some crazy dog ​​waves, it underestimates the possibility under special circumstances, so nonlinear focusing is more effective. In some cases, if the two interpretation mechanisms are unified, it will theoretically push the wave to an incredible height.
  Recently, however, a group of applied mathematicians has taken a different approach and turned to research how to predict mad dog waves. Professor Eric Vanden Einden of New York University established a statistical framework and developed a “one size fits all” model. This model predicts the probability of any mad dog wave, but doesn’t care how it happened.
  Aindon explained that the trick to uniformly describing the mad dog wave is to understand that extremely rare events have their own logic. You can use the probability of the least rare event to calculate the probability of a rare event very accurately, which is the big one in probability theory. Deviation theory. Aindon’s research team concluded that the turbulent ocean is the perfect theater to witness the theory of large deviations. A small wave can be formed in many ways, and a mad dog wave is particularly special. If you happen to see it, you will realize that only the right time, the right place, and the right people can create such a huge wave.
  To this end, Iinden’s team tested their theoretical framework with numerically simulated waves, asked the computer to generate random waves that meet certain ocean conditions, and then observed how each ocean evolves in relation to the nonlinear Schrodinger equation, and used large Bias theory predicts which piece of ocean is most likely to produce giant waves. As they hoped, they found that for a given type of numerically simulated ocean, only in a specific pattern will the initial ripple become a mad dog wave.
  Afterwards, the Irondon team conducted physical wave experiments and “rebuilt” the Dlopnier giant waves at the Marine Research Institute of the University of Edinburgh. The research facility consists of a nearly 270-meter-long tank and 168 wave generators. Each ocean is randomly generated by the wave generator. The research team recorded high-order statistics of typical wave heights, which not only proved that some crazy dog ​​waves are linear, some are non-linear, but also coexist with the two, and are highly consistent with the theory of large deviations.
  The theory of large deviation can be boiled down to an optimization problem, which can predict the prototype path from the initial ripple to the final huge wave. The whole process gradually unfolds like acting in a movie, and only by following this path can the final height be reached. The research shows that the highest wave in the experiment is in full agreement with the prediction of the framework: in the huge data, only more than 300 waves that can be regarded as mad dog waves were generated, and in most cases they did not.
  However, this framework also has limitations, because it does not consider the effects of ocean currents and wind and other phenomena, and allows waves to grow to any height, which is the result of its dependence on the nonlinear Schrodinger equation. However, the researchers say that their tools are transferable, and the nonlinear Schrodinger equation can be replaced with other wave theories. As theorists continue to improve their tools, researchers have begun to test the correctness of the large deviation theory in the waters near Antarctica.
  The ultimate goal of the researchers is to develop a device to predict mad dog waves. When the big deviation theory is modified and applied to the open ocean, this device can help sailors find it when the mad dog wave is in its bud and avoid disaster in time.