Wave Interactions with Coastal Structures

Due to the ongoing rise in sea level and increase in extreme wave climates, consequences of the changing wave climate, coastal structures such as sea dikes and seawalls will be exposed to severe and frequent sea storms [...]

An Entropy Paradox Free Fractional Diffusion Equation

A new look at the fractional diffusion equation was done. Using the unified fractional derivative, a new formulation was proposed, and the equation was solved for three different order cases: neutral, dominant time, and dominant space. The solutions were expressed by generalizations of classic formulae used for the stable distributions. The entropy paradox problem was studied and clarified through the Rényi entropy: in the extreme wave regime the entropy is −∞. In passing, Tsallis and Rényi entropies for stable distributions are introduced and exemplified.

Impact of Extratropical Cyclone Intensity and Speed on the Extreme Wave Trends in the Atlantic Ocean

This work analyzes the extratropical cyclone-related extreme waves in the ocean surface and their trends in the North and South Atlantic Oceans. Atmospheric and ocean wave products are obtained from ERA5, from 1979 to 2020 with 1-hourly outputs, covering 42 years with the present climate changes evaluated by the difference between the two 21-years time slices. The cyclones are tracked through the relative vorticity at 850 hPa and then associated with extreme wave events using an automated scheme that searches for an extreme wave region 1500 km from the centre of the cyclone, following criteria that exclude possible swell dominated events. The hot-spot regions of cyclone-related waves occurrence found by the method are in agreement with previous studies and are related to the cyclogenesis region and storm track orientation. Most cyclones associated with extreme wave events are generated in the western boundary of the domains. The east-poleward side of the ocean basins presents the highest density of occurrences related to the higher density of cyclone track and the dominance of more mature stage cyclones while in the west side prevail systems on developing stages, with notable propagating fronts and consequently, lower wind persistence. Changes in occurrence cannot be explained just by the storm track variation during the period due to the lack of statistical confidence. However, the wave occurrence responds to changes in the cyclone intensity, modulated by cyclone displacement speed. Regions with an increase of extreme waves are related to the effect of more intense cyclones or cyclones with slower propagation, being the last associated with a longer interaction of winds with the ocean surface.