Due to a lack of appropriate modelling tools, the atmospheric source mechanisms triggering the potentially destructive meteotsunami waves – occurring at periods from a few minutes to a few hours – have remained partially unstudied till recently. In this numerical work we thus investigate and quantify the impacts of orography and extreme climate changes on the generation and propagation of the atmospheric pressure disturbances occurring during six different historical meteotsunami events in the Adriatic Sea. Additionally, the impact of the bathymetry, and hence the Proudman resonance, on the propagation of the meteotsunami waves is also assessed for the same ensemble of events. Our main findings can be summarized as follow: (1) removing the mountains does not strongly affect the generation nor the propagation of the meteotsunamigenic disturbances but can slightly increase their intensity particularly over the land, (2) climate warming under extreme scenario has the potential to increase the intensity of both atmospheric disturbances and meteotsunami waves in the vicinity of the sensitive coastal areas while (3) flattening the bathymetry of the deepest Adriatic Sea tends to divert the meteotsunami waves from the sensitive harbour locations. Such sensitivity studies, if generalized to other geographical locations with a higher number of events, may provide new insights concerning the still unknown physics of the meteotsunami genesis and, consequently, help to better mitigate meteotsunami hazards worldwide.

Ivica Vilibic

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The northernmost part of the Mediterranean Sea, the northern Adriatic shelf, is a complex area where the intensity of dense water formation and the consequent Adriatic-Ionian thermohaline circulation are shaped by a combination of extreme wintertime bora winds and substantial freshwater loads. To better understand the impact of global warming on extreme bora dynamics and the associated sea surface cooling, we applied the Adriatic Sea and Coast (AdriSC) kilometer-scale modelling suite to the far future climate (2060-2100) period. Under both Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 greenhouse emission scenarios, the AdriSC simulations are carried out via the combination of a statistical approach – consisting of an ensemble of 3-day simulations for 22 extreme bora events, and a pseudo-global warning (PGW) methodology – imposing a climatological change to the forcing used to produce the evaluation (present climate) runs. Despite a noteworthy decrease in intensity of the bora winds (by up to 3 m/s), the intensity of the negative latent heat fluxes is simulated to increase (by up to 150 W/m2) due to the reduction in relative humidity in the northern Adriatic (by up to 3%). Consequently, the sea surface cooling associated with severe bora events and preconditioning the dense shelf water formation in the northern Adriatic is projected to not significantly change compared to present climate. Although these results need to be further confirmed, this study thus provides a new view on the future of processes driven by sea surface cooling, such as the dense shelf water formation or the Ionian-Adriatic thermohaline circulation, that were projected to decrease in the future climate by regional climate models an order of magnitude coarser than the AdriSC simulations.