Predicting surface weather at sea has always been a challenge with very high stakes. For instance,
However, as the elder notes in his articleResearcher at Skoltech and the Physics Institute. P.N. Lebedev Institute of RAS Andrey Pushkarev, coastlines complicate the situation. The fact is that forecasting disturbances in the English Channel is almost as difficult today as it was in 1944. Research by the Russian scientist shows that the behavior of waves in channels or straits will differ significantly from the behavior of waves in the open sea.
“Coastlines create heterogeneity -the gradient of the wave energy distribution between its zero value at the boundary and a nonzero value on the shore. This gradient triggers the advection of waves, which, as a result, leads to special effects of wave generation, orthogonal to the wind, ”explains Pushkarev.
Specific conditions of channels and straitsallow you to accurately solve the Hasselman equation. It describes wave behavior similar to single-current models. However, it is still impossible to solve with modern computers. Pushkarev's theoretical modeling of wave formation in a strait resembling the English Channel showed that the development of turbulence did not correspond to the predictions of traditional models. The fact is that the structure of turbulence was significantly different due to nonlinear interactions and advection of waves. Since the observed phenomenon has some similarities to laser radiation, it is called the Nonlinear Ocean Wave Amplifier or NOWA.
The shores of the strait play the role of semi-reflecting mirrors for the generated waves.
New model using exact versionHasselman's equations shows that the existing operational models of weather forecasting on waves do not take into account this effect, considering the reflection to be rather an artifact.
Laser-like wave generationperpendicular to the wind can be observed not only in the straits, but also in the open sea with specific inhomogeneous winds. There, spatial wind turning points create conditions similar to those observed in a body of water with shores.
New research promises to explain natureseiches, a kind of standing waves in semi-enclosed reservoirs, which are a big problem for ships in ports. They are called "murderous" because of their destructive effect. But it also suggests that properly describing turbulence in the presence of a coastline will allow for rogue waves, seemingly unpredictable surface waves that are extremely dangerous even for large ships.
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