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Due to a lack of suitable coupled atmosphere‐ocean modeling tools, the atmospheric source mechanisms that trigger the potentially destructive meteotsunami waves – which occur with periods ranging from a few minutes to a few hours – have remained partially unexplored until recently. In this process‐oriented numerical work we therefore investigate and quantify the impacts of orography and extreme climate changes on the generation and propagation of the atmospheric pressure disturbances that occurred during six different historical meteotsunami events in the Adriatic Sea. In addition, the impact of bathymetry, and hence Proudman resonance, on the propagation of the meteotsunami waves is investigated for the same ensemble of events. Our main findings can be summarized as follows: (a) Removing the mountains does not have a strong effect on either the generation or propagation of the meteotsunamigenic disturbances but may slightly increase their intensity, especially over land; (b) Extreme climate warming has the potential to increase the intensity of both atmospheric disturbances and meteotsunami waves near sensitive coastal areas; while (c) Flattening the bathymetry of the deepest Adriatic Sea tends to deflect the meteotsunami waves away from sensitive harbor locations. Such sensitivity studies, if generalized to other geographic locations with a higher number of events, may provide new insights into the still unknown physics of meteotsunami generation. Plain Language Summary: Among extreme sea‐level hazards, meteotsunami waves – which occur at periods from a few minutes to a few hours – remain the least studied due to a lack of suitable high‐resolution coupled atmosphere‐ocean modeling tools. Consequently, neither the impact of orography and bathymetry on meteotsunamigenic disturbances and meteotsunami waves nor their characteristics in a projected future climate have been properly quantified. In this process‐oriented numerical work we analyze these impacts using sensitivity experiments for six different meteotsunami events in the Adriatic Sea. We found that meteotsunamigenic disturbances are not strongly modulated by the orography which can reinforced their intensity, but could be significantly increased under extreme climate warming. In addition, flattening the bathymetry of the deepest ocean parts tends to deflect the meteotsunami waves away from the sensitive harbor locations. Because meteotsunami events have the potential to cause substantial human and structural damage worldwide, this type of studies may be critical to better understand their key physical processes. Key Points: Sensitivity of meteotsunami generation and propagation to some environmental conditions is quantified in the Adriatic SeaRemoving mountains has little impact on meteotsunamis while flattening the bathymetry diverts them from the coastsExtreme climate warming could increase the meteotsunami wave intensities along the most sensitive Adriatic coastal areas [ABSTRACT FROM AUTHOR]

The meteotsunami early warning system prototype using stochastic surrogate approach and running operationally in the eastern Adriatic Sea is presented. First, the atmospheric internal gravity waves (IGWs) driving the meteotsunamis are either forecasted with state‐of‐the‐art deterministic models at least a day in advance or detected through measurements at least 2 hr before the meteotsunami reaches sensitive locations. The extreme sea‐level hazard forecast at endangered locations is then derived with an innovative stochastic surrogate model—implemented with generalized polynomial chaos expansion (gPCE) method and synthetic IGWs forcing a barotropic ocean model—used with the input parameters extracted from deterministic model results and/or measurements. The evaluation of the system, both against five historical events and for all the detected potential meteotsunamis since late 2018 when the early warning system prototype became operational, reveals that the meteotsunami hazard is conservatively assessed but often overestimated at some locations. Despite some needed improvements and developments, this study demonstrates that gPCE‐based methods can be used for atmospherically driven extreme sea‐level hazard assessment and in geosciences in wide. Plain Language Summary: Atmospherically driven extreme sea‐level events are one of the major threats to people and assets in the coastal regions. Assessing the hazard associated with such events together with uncertainty quantification in a precise and timely manner is thus of primary importance in modern societies. In this study, an early warning system for the eastern Adriatic meteotsunamis, destructive long waves with periods from few minutes up to an hour generated by traveling atmospheric disturbances, is presented and evaluated. The system is based on state‐of‐the‐art deterministic atmospheric and ocean models as well as an innovative statistical model developed to forecast the meteotsunami hazard. The evaluation reveals that the meteotsunami hazard is conservatively assessed but often overestimated. This study demonstrates that the presented methodology can be used for extreme sea‐level hazard assessment and in general for hazard studies in geosciences. Key Points: Design and evaluation of an innovative meteotsunami early warning system prototype using stochastic surrogate approachForecast of the atmospheric internal gravity waves driving meteotsunami events with deterministic state‐of‐the‐art modelsStochastic surrogate model based on generalized polynomial chaos expansion methods and running at nearly no computational cost [ABSTRACT FROM AUTHOR]

In engineering studies, harbor resonance, including quality and amplification factors, is typically computed for swell and waves with periods shorter than 10 min. However, in various locations around the world, such as Vela Luka Bay in Croatia, meteotsunami waves of periods greater than 10 min can excite the bay or harbor natural modes and produce substantial structural damages. In this theoretical study, the impact of some geomorphological changes of Vela Luka Bay—i.e. deepening of the bay, dredging the harbor, adding a pier or a marina—to the amplification of the meteotsunami waves are presented for a set of 6401 idealized pressure wave field forcing used to derive robust statistics. The most substantial increase in maximum elevation is found when the Vela Luka harbor is dredged to a 5 m depth, which is in contradiction with the calculation of the quality factor showing a decrease of the harbor natural resonance. It has been shown that the forcing energy content at different frequency bands should also be taken into account when estimating the quality and amplification factors, as their typical definitions derived from the peak frequency of the sea level spectrum fail to represent the harbor response during meteotsunami events. New definitions of these factors are proposed in this study and are shown to be in good agreement with the results of the statistical analysis of the Vela Luka Bay maximum elevation results. In addition, the presented methodology can easily be applicable to any other location in the world where meteotsunamis occur. [ABSTRACT FROM AUTHOR]

A major tsunami-like event, locally known as ‘marrobbio’, impacted the southwestern coast of Sicily on 25-26 June 2014. The event was part of a chain of hazardous episodes in the Mediterranean and Black seas during the last week of June 2014 resulting from an anomalous atmospheric system (“tumultuous atmosphere”) propagating eastward over the region. The synoptic patterns and vertical structure of the atmosphere over Sicily at the time of the event indicate that atmospheric wave ducting was responsible for the generation of tsunamigenic air pressure disturbances that produced especially high sea level responses (“meteotsunamis”) at certain sites along the Sicilian coast. The strongest sea level oscillations were observed at Mazara del Vallo, where a 1-m meteotsunami bore, propagating upstream in the Mazaro River, was generated. The combined effects of external resonance (Proudman resonance on the western Sicilian shelf) and internal resonant conditions (bathymetric and topographic characteristics of specific sites) were found to be the key factors that caused the meteotsunami (marrobbio phenomenon) on the coast of Sicily and the meteobore at Mazara del Vallo. [ABSTRACT FROM AUTHOR]

The paper provides a comprehensive review of all aspects of Adriatic Sea level research covered by the literature. It discusses changes occurring over millennial timescales and documented by a variety of natural and man-made proxies and post-glacial rebound models; mean sea level changes occurring over centennial to annual timescales and measured by modern instruments; and daily and higher-frequency changes (with periods ranging from minutes to a day) that are contributing to sea level extremes and are relevant for present-day flooding of coastal areas. Special tribute is paid to the historic sea level studies that shaped modern sea level research in the Adriatic, followed by a discussion of existing in situ and remote sensing observing systems operating in the Adriatic area, operational forecasting systems for Adriatic storm surges, as well as warning systems for tsunamis and meteotsunamis. Projections and predictions of sea level and related hazards are also included in the review. Based on this review, open issues and research gaps in the Adriatic Sea level studies are identified, as well as the additional research efforts needed to fill the gaps. The Adriatic Sea, thus, remains a laboratory for coastal sea level studies for semi-enclosed, coastal and marginal seas in the world ocean. [ABSTRACT FROM AUTHOR]

A series of meteotsunamis hit a few locations in the Mediterranean and Black Seas during 22-27 June 2014. Meteotsunamis were particularly numerous on 25 and 26 June in the Adriatic Sea, where at least six harbours and bays were stricken by powerful waves: strongest events occurred in Vela Luka (Korčula Island), a known meteotsunami hot-spot, where waves reached height of ~3 m, and in Rijeka dubrovačka Bay, where strong ~5 m/s currents accompanied ~2.5 m high waves. Intensification of high-frequency sea level activity was observed at both the eastern and western Adriatic tide gauge stations, with maximum recorded wave heights reaching ~68 cm (Ortona, Italy). A series of individual air pressure disturbances characterized by pronounced rates of air pressure change (up to 2.4 hPa/5 min), limited spatial extent (~50 km) and high temporal variability, propagated over the Adriatic on 2 days in question. Numerical hydrodynamic model SCHISM forced by measured and idealised air pressure disturbances was utilised to reproduce the observed Adriatic sea level response. Several important conclusions were reached: (1) meteotsunamis occurring at various parts of the coast were generated by different atmospheric air pressure disturbances; (2) topographic influence can be removed from sea level spectra by computing spectral signal-to-background ratios; the result, being related to the external forcing, resembles atmospheric pressure spectra; (3) sea response is strongly dependant on details of atmospheric forcing; and (4) over complex bathymetries, like the middle and south Adriatic ones, numerous effects, including Proudman resonance, edge waves, strong topographical enhancement and refractions on the islands placed on the pathway of atmospheric disturbances should be taken into account to fully understand meteotsunami generation and dynamics. An in-depth numerical study is planned to supplement the latter conclusion and to quantify contribution of each process. [ABSTRACT FROM AUTHOR]

The author focuses on meteorological tsunamis, also known as meteotsunamis, that have destructed parts of world oceans. He states that meteotsunamis are natural disasters and seiches are observed at several coasts, including Spain, Japan and East Coast of U.S. An overview of seismic activity, gravity waves, submarine landslides and squalls is offered.

The article aims to test the sensitivity of high-resolution mesoscale atmospheric model to fairly reproduce atmospheric processes that were present during the Boothbay Harbor meteotsunami on 28 October 2008. The simulations were performed by the Weather and Research Forecasting (WRF) model at 1-km horizontal grid spacing by varying initial conditions (ICs) and lateral boundary conditions (LBCs), nesting strategy, simulation lead time and microphysics and convective parameterizations. It seems that the simulations that used higher-resolution IC and LBC were more successful in reproduction of precipitation zone and surface pressure oscillations caused by internal gravity waves observed during the event. The results were very sensitive to the simulation lead time and to the choice of convective parameterization, while the choice of microphysics parameterization and the type of nesting strategy (one-way or two-way) was less important for reproducibility of the event. The success of the WRF model appears limited to very short-range forecasting, most advanced parameterizations, and very high-resolution grid spacing; therefore, the applicability of present atmospheric mesoscale models to future operational meteotsunami warning systems still has a lot of room for improvements. [ABSTRACT FROM AUTHOR]

A series of tsunami-like waves of non-seismic origin struck several southern European countries during the period of 23 to 27 June 2014. The event caused considerable damage from Spain to Ukraine. Here, we show that these waves were long-period ocean oscillations known as meteorological tsunamis which are generated by intense small-scale air pressure disturbances. An unique atmospheric synoptic pattern was tracked propagating eastward over the Mediterranean and the Black seas in synchrony with onset times of observed tsunami waves. This pattern favoured generation and propagation of atmospheric gravity waves that induced pronounced tsunami-like waves through the Proudman resonance mechanism. This is the first documented case of a chain of destructive meteorological tsunamis occurring over a distance of thousands of kilometres. Our findings further demonstrate that these events represent potentially dangerous regional phenomena and should be included in tsunami warning systems. [ABSTRACT FROM AUTHOR]

Abstract The paper presents the Adriatic Sea and Coast (AdriSC) Meteotsunami Forecast system, which has been developed to operationally forecast meteotsunamis – atmospherically-generated destructive ocean waves in the tsunami frequency band, in the Adriatic Sea. The challenges posed by modelling meteotsunamis are first reviewed, then the AdriSC Meteotsunami Forecast system set-up is presented in detail and finally the atmosphere and ocean model results are evaluated against 48 air pressure sensors and 19 tide gauges for six different meteotsunami events. The statistical analysis of the high-frequency model results reveals that the AdriSC atmospheric and ocean models can reproduce meteotsunami events, even though their performances highly vary depending on the event and observation location. A qualitative analysis of the maps of extreme sea level and mean sea level pressure high-frequency model results shows that even a slight shift in location (of the order of 1 to 10 km) of the atmospheric disturbances, responsible for the meteotsunami generation, results in the incapability of the ocean models to reproduce the observed floods occurring during the meteotsunami events. This study presents the first available thorough evaluation of a deterministic meteotsunami forecast system. As such, it establishes that a carefully envisioned modelling system, even if imperfect, can be implemented to reproduce and forecast meteotsunami events. Highlights • A modelling suite for operational forecast of meteotsunamis was developed. • Prerequisites for meteotsunami modelling are at the edge of the model performances. • Meteotsunami events have been qualitatively reproduced in the Adriatic Sea. • The suite can be used for hazard assessment within a meteotsunami warning system. [ABSTRACT FROM AUTHOR]