In engineering studies, harbor resonance, including quality and amplification factors, is typical... more 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.
Acta Adriatica: International Journal of Marine Sciences, 2023
This review first pays tribute to the famous Croatian oceanographer, Mira Zore-Armanda, and her s... more This review first pays tribute to the famous Croatian oceanographer, Mira Zore-Armanda, and her seminal work on the Adriatic water masses in 1963, and emphasises the importance of the densest Mediterranean water mass: North Adriatic Dense Water (NAddW). This water mass is generated through substantial wintertime surface cooling and evaporation over the wide northern Adriatic and is known to (1) influence the Adriatic-Ionian thermohaline circulation, (2) bring oxygen and carbon to the deep Adriatic layers and, (3) more generally, have a substantial impact on the physics and biogeochemistry of the whole Adriatic. Second, the NAddW physics, from preconditioning, through generation and spreading, to accumulation in Adriatic depressions, is reviewed. Then, the temporal evolution of the NAddW properties influenced and connected to (1) basin-wide interannual and decadal variability and (2) trends towards warmer and saltier source characteristic due to ongoing climate change, is discussed. The importance of long-term observations and atmosphere-ocean modelling in event, decadal and climate studies is then presented. Finally, a review of the identified gaps and perspectives for future research is concluding this article.
In order to analyse the differences between the results of the four simulations several additiona... more In order to analyse the differences between the results of the four simulations several additional analyses were performed. The presented supplementary material (Fig. S1 to S5 and text) complements the results of the article titled "Multi-model analysis of the Adriatic dense water dynamics". In particular, supplementary results include (a) spatial distributions of minimum bottom temperature and maximum bottom salinity and the corresponding timing of the extremes, (b) time series of daily bottom temperature and salinity in four subdomains and (c) daily volume transport along selected transects. S2 Results S2.1 Analysis of the extremes Spatial distributions of minimum bottom temperature and the corresponding timing of the minimums for the four simulations are shown on Fig. S1. In general, lowest temperatures are reproduced in the northern Adriatic down to 5 °C, along the western coast and in Kvarner Bay, while highest minimums are found in shallower parts of southern Adriatic up to 15 °C. MEDSEA minimums mostly occurred in winter, in the western part of middle Adriatic during spring, whereas in Jabuka Pit minimum temperatures were reproduced in autumn 2014 (Fig. S1a and b). For ROMS hind, the main difference is in the Jabuka Pit where the minimums occurred in summer (Fig. S1c and d). ROMS full minimums mostly happened in winter but also in spring in a part of Kvarner Bay and in the middle Adriatic (Fig. S1e and f). It can be seen that ROMS full reproduced lowest temperatures in a patch in the northern Adriatic. For AdriSC ROMS, temperature minimums are also present mostly in winter while in parts of the middle Adriatic including Jabuka Pit they occurred in spring (Fig. S1g and h). In the SAP, minimums are mostly reproduced in autumn and partly in winter and spring by all models.
(2022) Different life strategies of the three commercially exploited scallop species living under... more (2022) Different life strategies of the three commercially exploited scallop species living under the same environmental conditions.
This study aims to enhance our understanding of the bora-driven dense-water dynamics in the Adria... more This study aims to enhance our understanding of the bora-driven dense-water dynamics in the Adriatic Sea using different state-of-the-art modelling approaches during the 2014-2015 period. Practically, we analyse and compare the results of the following four different simulations: the latest reanalysis product for the Mediterranean Sea, a recently evaluated fine-resolution atmosphere-ocean Adriatic Sea climate model, and a long-time-running Adriatic Sea atmosphere-ocean forecast model used in both hindcast and data assimilation (with 4 d cycles) modes. As a first step, we evaluate the resolved physics in each simulation by focusing on the performance of the models. Then, we derive the general conditions in the ocean and the atmosphere during the investigated period. Finally, we analyse in detail the numerical reproduction of the dense-water dynamics as seen by the four simulations. The likely prerequisites for proper modelling of the ocean circulation in the Adriatic basin, including a kilometre-scale atmosphere-ocean approach, nonhydrostatic atmospheric models, fine vertical resolutions in both atmosphere and ocean, and the location and forcing of the open boundary conditions, are thus discussed in the context of the different simulations. In conclusion, a 31-yearlong run of the fine-resolution Adriatic Sea climate model is found to be able to outperform most aspects of the reanalysis product, the short-term hindcast, and the data-assimilated simulation in reproducing the dense-water dynamics in the Adriatic Sea.
In this evaluation study, the coupled atmosphereocean Adriatic Sea and Coast (AdriSC) climate mod... more In this evaluation study, the coupled atmosphereocean Adriatic Sea and Coast (AdriSC) climate model, which was implemented to carry out 31-year evaluation and climate projection simulations in the Adriatic and northern Ionian seas, is briefly presented. The kilometre-scale AdriSC atmospheric results, derived with the Weather Research and Forecasting (WRF) 3 km model for the 1987-2017 period, are then thoroughly compared to a comprehensive publicly and freely available observational dataset. The evaluation shows that overall, except for the summer surface temperatures, which are systematically underestimated, the AdriSC WRF 3 km model has a far better capacity to reproduce surface climate variables (and particularly the rain) than the WRF regional climate models at 0.11 • resolution. In addition, several spurious data have been found in both gridded products and in situ measurements, which thus should be used with care in the Adriatic region for climate studies at local and regional scales. Long-term simulations with the AdriSC climate model, which couples the WRF 3 km model with a 1 km ocean model, might thus be a new avenue to substantially improve the reproduction, at the climate scale, of the Adriatic Sea dynamics driving the Eastern Mediterranean thermohaline circulation. As such it may also provide new standards for climate studies of orographically developed coastal regions in general.
This numerical work aims to better understand the behavior of extreme Adriatic Sea wave storms un... more This numerical work aims to better understand the behavior of extreme Adriatic Sea wave storms under projected climate change. In this spirit, 36 characteristic events-22 bora and 14 sirocco storms occurring between 1979 and 2019, were selected and ran in evaluation mode in order to estimate the skill of the kilometer-scale Adriatic Sea and Coast (AdriSC) modelling suite used in this study and to provide baseline conditions for the climate change impact. The pseudo-global warming (PGW) methodology-which imposes an additional climatological change to the forcing used in the evaluation simulations, was implemented, for the very first time, for a coupled ocean-wave-atmosphere model and used to assess the behavior of the selected storms under Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 greenhouse gas projections. The findings of this experiment are that, on the one hand, the AdriSC model is found capable of reproducing both the Adriatic waves associated with the 36 storms and the northern Adriatic surges occurring during the sirocco events and, on the other hand, the significant wave heights and peak periods are likely to decrease during all future extreme events but most particularly during bora storms. The northern Adriatic storm surges are in consequence also likely to decrease during sirocco events. As it was previously demonstrated that the Adriatic extreme wind-wave events are likely to be less intense in a future warmer climate, this study also proved the validity of applying the PGW methodology to coupled ocean-wave-atmosphere models at the coastal and nearshore scales.
This study aims to enhance our understanding of the bora-driven dense-water dynamics in the Adria... more This study aims to enhance our understanding of the bora-driven dense-water dynamics in the Adriatic Sea using different state-of-the-art modelling approaches during the 2014-2015 period. Practically, we analyse and compare the results of the following four different simulations: the latest reanalysis product for the Mediterranean Sea, a recently evaluated fine-resolution atmosphere-ocean Adriatic Sea climate model, and a long-time-running Adriatic Sea atmosphere-ocean forecast model used in both hindcast and data assimilation (with 4 d cycles) modes. As a first step, we evaluate the resolved physics in each simulation by focusing on the performance of the models. Then, we derive the general conditions in the ocean and the atmosphere during the investigated period. Finally, we analyse in detail the numerical reproduction of the dense-water dynamics as seen by the four simulations. The likely prerequisites for proper modelling of the ocean circulation in the Adriatic basin, including a kilometre-scale atmosphere-ocean approach, nonhydrostatic atmospheric models, fine vertical resolutions in both atmosphere and ocean, and the location and forcing of the open boundary conditions, are thus discussed in the context of the different simulations. In conclusion, a 31-yearlong run of the fine-resolution Adriatic Sea climate model is found to be able to outperform most aspects of the reanalysis product, the short-term hindcast, and the data-assimilated simulation in reproducing the dense-water dynamics in the Adriatic Sea.
<p>Meteotsunami events – tsunami-like ocean waves driven by atmospher... more <p>Meteotsunami events – tsunami-like ocean waves driven by atmospheric disturbances – are, by nature, rare, specific to certain geographical regions and highly variable in time. Consequently, the coastal hazards due to these types of events are known to be difficult to forecast with state-of-the art numerical models presently applied around the world.</p> <p>In order to help the local communities to better prepare for these destructive events (e.g., set temporary protection against flooding and waves, avoid swimming, etc.) and minimize the losses, the Croatian Meteotsunami Early Warning System (CMeEWS) has been recently implemented in the Adriatic Sea in the testing mode. The CMeEWS is mostly based on the Adriatic Sea and Coast (AdriSC) modelling suite and uses an innovative deterministic-stochastic approach for extreme sea-level event predictions. It provides meteotsunami hazard forecasts depending on (1) daily deterministic forecasts by coupled kilometer-scale atmosphere-ocean models, (2) atmospheric observations and (3) stochastic forecasts of extreme sea-level distributions at endangered locations derived with a surrogate model approach. Some of these steps require substantial computational resources and needs an optimized data flow which, at end, defines the operability of the service.</p> <p>Here, the advantages but also the drawbacks of such an approach will be presented through several applications of the AdriSC modelling suite during meteotsunami events in the Adriatic Sea. The future challenges concerning meteotsunami extreme sea-level modelling will be discussed and some potential avenues to further develop the model skills will be considered.</p>
In this study, the Adriatic Sea and Coast (AdriSC) kilometre-scale atmosphere-ocean climate model... more In this study, the Adriatic Sea and Coast (AdriSC) kilometre-scale atmosphere-ocean climate model covering the Adriatic Sea and northern Ionian Sea is presented. The AdriSC ocean results of a 31-year-long (i.e. 1987-2017) climate simulation, derived with the Regional Ocean Modeling System (ROMS) 3 km and 1 km models, are evaluated with respect to a comprehensive collection of remote sensing and in situ observational data. In general, it is found that the AdriSC model is capable of reproducing the observed sea surface properties, daily temperatures and salinities, and the hourly ocean currents with good accuracy. In particular, the AdriSC ROMS 3 km model demonstrates skill in reproducing the main variabilities of the sea surface height and the sea surface temperature, despite a persistent negative bias within the Adriatic Sea. Furthermore, the AdriSC ROMS 1 km model is found to be more capable of reproducing the observed thermohaline and dynamical properties than the AdriSC ROMS 3 km model. For the temperature and salinity, better results are obtained in the deeper parts than in the shallow shelf and coastal parts, particularly for the surface layer of the Adriatic Sea. The AdriSC ROMS 1 km model is also found to perform well in reproducing the seasonal thermohaline properties of the water masses over the entire Adriatic-Ionian domain. The evaluation of the modelled ocean currents revealed better results at locations along the eastern coast and especially the northeastern shelf than in the middle eastern coastal area and the deepest part of the Adriatic Sea. Finally, the AdriSC climate component is found to be a more suitable modelling framework to study the dense water formation and long-term thermohaline circulation of the Adriatic-Ionian basin than the available Mediterranean regional climate models.
Journal Of Geophysical Research: Atmospheres, Feb 26, 2021
In process‐oriented studies, accurate representation of severe bora rotor dynamics in the norther... more In process‐oriented studies, accurate representation of severe bora rotor dynamics in the northern Adriatic is known to require the use of model resolutions of the order of 100 m. In regional climate studies, computation time and numerical cost are, however, minimized with resolutions of the order of 10 km. The latter is not accurate enough to drive the coastal dense water formation and the long‐term Adriatic‐Ionian thermohaline circulation resulting from these events. This work leverages the capacity of kilometer‐scale atmospheric models to balance accuracy and efficiency in coupled atmosphere‐ocean climate studies in the Adriatic Sea. The sensitivity of severe bora dynamics and air‐sea interactions to atmospheric model resolution is thus tested within the Adriatic Sea and Coast (AdriSC) modeling suite as well as with the best available reanalysis. The Weather Research and Forecasting (WRF) model at 15‐km, 3‐km, and 1.5‐km resolution, and ERA5 at 30‐km resolution, are compared for an ensemble of 22 severe bora storms spanning between 1991 and 2019. It is found that (1) ERA5 reanalysis and WRF 15‐km model highly diverge (up to 43% for the wind speed) from WRF 3‐km results while (2) WRF 3‐km conditions converge toward the WRF 1.5‐km solution for both basic bora dynamics (differences below 6% for the wind speed) and air‐sea interactions (differences 5 times smaller than with WRF 15‐km results). Consequently, kilometer‐scale atmospheric models should be used to reproduce properly the dense water formation during severe bora events and the long‐term thermohaline circulation of the Adriatic‐Ionian basin.
In engineering studies, harbor resonance, including quality and amplification factors, is typical... more 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.
. Due to on-going global warming, extreme storm surges are expected to threaten a greater number ... more . Due to on-going global warming, extreme storm surges are expected to threaten a greater number of coastal communities worldwide. However, global and regional climate simulations of extreme events are still not accurate enough to respond to the growing needs of the local decision makers to prepare for these rising hazards. We present a new approach using (sub-)kilometre-scale coupled atmosphere-ocean-wave models and demonstrate the feasibility to provide meter-scale assessments of the impact of climate change on storm surge hazards. As a proof of concept, we focus in the Adriatic Sea and analyse the sea levels of two kilometre-scale 31-year long simulations used in evaluation and extreme warming modes. First, we demonstrate that, at 1-km resolution, the model errors are reduced by up to a third compare to state-of-the-art regional and global models. Second, we show that meter-scale storm surge results – obtained by further downscaling extreme events extracted from the kilometre-scale simulations – contrast with the previously published literature. In particular, we found that some understudied regions of the Adriatic coast might be more vulnerable to sea level rise and atmospherically driven storm surges induced by extreme climate warming than the well-researched Venice Lagoon. Following these preliminary results, we present a newly developed methodology directly downscaling extreme events from global climate models. Within this framework, the numerical resources, previously spent to produce long-term simulations, are used efficiently to quantify the climate change uncertainty and to properly assess the meter-scale storm surge hazards.
In this study, the Adriatic Sea and Coast (AdriSC) kilometre-scale atmosphere-ocean climate model... more In this study, the Adriatic Sea and Coast (AdriSC) kilometre-scale atmosphere-ocean climate model covering the Adriatic and northern Ionian Seas is presented. The AdriSC ocean results of a 31-year long (i.e. 1987-2017) climate simulation, derived with the Regional Ocean Modeling System (ROMS) 3-km and 1-km models, are evaluated with respect to a comprehensive collection of remote-sensing and in situ observational data. In general, it is found that the AdriSC model is capable to reproduce the observed sea-surface properties, daily temperatures and salinities and the hourly ocean currents with good accuracy. In particular, the AdriSC ROMS 3-km model demonstrates skill in reproducing the main variabilities of the sea-surface height as well as the sea-surface temperature, despite a persistent negative bias within the Adriatic Sea. Furthermore, the AdriSC ROMS 1-km model is found to be more capable to reproduce the observed thermohaline and dynamical properties than the AdriSC ROMS 3-km model. For the temperature and salinity, better results are obtained in the deeper parts than in the shallow shelf and coastal parts, particularly for the surface layer of the Adriatic Sea. The AdriSC ROMS 1-km model is also found to perform well in reproducing the seasonal thermohaline properties of the water masses over the entire Adriatic-Ionian domain. The evaluation of the modelled ocean currents revealed better results at locations along the eastern coast and especially the northeastern shelf than in the middle-eastern coastal area and the deepest part of the Adriatic Sea. Finally, the AdriSC climate component is found to be a more suitable modelling framework to study the dense water formation and long-term thermohaline circulation of the Adriatic-Ionian basin than the available Mediterranean regional climate models. 1 Introduction Due to the temporal and spatial sparsity of the in situ observations, the study of the dynamics and variability of the ocean processes mostly relies on the constant developments and improvements of the available numerical modelling tools. Over the years, in the Adriatic Sea, significant progresses have thus been made by the ocean modelling community to overcome the challenges posed by the complex geomorphology of the region (Figs. 1.a and 1.b): (1) an extremely complex coastline with
Bulletin of the American Meteorological Society, 2023
Worldwide tsunamis driven by atmospheric waves-or planetary meteotsunami waves-are extremely rare... more Worldwide tsunamis driven by atmospheric waves-or planetary meteotsunami waves-are extremely rare events. They mostly occur during supervolcano explosions or asteroid impacts capable to generate atmospheric acoustic-gravity waves including the Lamb waves that can circle the globe multiple times. Recently, such ocean waves have been globally recorded after the Hunga Tonga-Hunga Ha'apai volcano eruption on 15 January 2022, but did not pose any serious danger to the coastal communities. However, this study highlights that the mostly ignored destructive potential of planetary meteotsunami waves can be compared to the well-studied tsunami hazards. In practice, several process-oriented numerical experiments are designed to force a global ocean model with the realistic atmospheric response to the Hunga Tonga-Hunga Ha'apai event rescaled in speed and amplitude. These simulations demonstrate that the meteotsunami surges can be higher than 1 m (and up to 10 m) along more than 7% of the world coastlines. Planetary meteotsunami waves thus have the potential to cause serious coastal damages and even human casualties during volcanic explosions or asteroid impacts either releasing intense acoustic energy or producing internal atmospheric gravity waves triggering the deep-ocean Proudman resonance at a speed of ~212 m s −1. Based on records of catastrophic events in Earth's history, both scenarios are found to be realistic, and consequently, the global meteotsunami hazards should now be properly assessed to prepare for the next big volcanic eruption or asteroid impact even occurring inland.
In engineering studies, harbor resonance, including quality and amplification factors, is typical... more 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.
Acta Adriatica: International Journal of Marine Sciences, 2023
This review first pays tribute to the famous Croatian oceanographer, Mira Zore-Armanda, and her s... more This review first pays tribute to the famous Croatian oceanographer, Mira Zore-Armanda, and her seminal work on the Adriatic water masses in 1963, and emphasises the importance of the densest Mediterranean water mass: North Adriatic Dense Water (NAddW). This water mass is generated through substantial wintertime surface cooling and evaporation over the wide northern Adriatic and is known to (1) influence the Adriatic-Ionian thermohaline circulation, (2) bring oxygen and carbon to the deep Adriatic layers and, (3) more generally, have a substantial impact on the physics and biogeochemistry of the whole Adriatic. Second, the NAddW physics, from preconditioning, through generation and spreading, to accumulation in Adriatic depressions, is reviewed. Then, the temporal evolution of the NAddW properties influenced and connected to (1) basin-wide interannual and decadal variability and (2) trends towards warmer and saltier source characteristic due to ongoing climate change, is discussed. The importance of long-term observations and atmosphere-ocean modelling in event, decadal and climate studies is then presented. Finally, a review of the identified gaps and perspectives for future research is concluding this article.
In order to analyse the differences between the results of the four simulations several additiona... more In order to analyse the differences between the results of the four simulations several additional analyses were performed. The presented supplementary material (Fig. S1 to S5 and text) complements the results of the article titled "Multi-model analysis of the Adriatic dense water dynamics". In particular, supplementary results include (a) spatial distributions of minimum bottom temperature and maximum bottom salinity and the corresponding timing of the extremes, (b) time series of daily bottom temperature and salinity in four subdomains and (c) daily volume transport along selected transects. S2 Results S2.1 Analysis of the extremes Spatial distributions of minimum bottom temperature and the corresponding timing of the minimums for the four simulations are shown on Fig. S1. In general, lowest temperatures are reproduced in the northern Adriatic down to 5 °C, along the western coast and in Kvarner Bay, while highest minimums are found in shallower parts of southern Adriatic up to 15 °C. MEDSEA minimums mostly occurred in winter, in the western part of middle Adriatic during spring, whereas in Jabuka Pit minimum temperatures were reproduced in autumn 2014 (Fig. S1a and b). For ROMS hind, the main difference is in the Jabuka Pit where the minimums occurred in summer (Fig. S1c and d). ROMS full minimums mostly happened in winter but also in spring in a part of Kvarner Bay and in the middle Adriatic (Fig. S1e and f). It can be seen that ROMS full reproduced lowest temperatures in a patch in the northern Adriatic. For AdriSC ROMS, temperature minimums are also present mostly in winter while in parts of the middle Adriatic including Jabuka Pit they occurred in spring (Fig. S1g and h). In the SAP, minimums are mostly reproduced in autumn and partly in winter and spring by all models.
(2022) Different life strategies of the three commercially exploited scallop species living under... more (2022) Different life strategies of the three commercially exploited scallop species living under the same environmental conditions.
This study aims to enhance our understanding of the bora-driven dense-water dynamics in the Adria... more This study aims to enhance our understanding of the bora-driven dense-water dynamics in the Adriatic Sea using different state-of-the-art modelling approaches during the 2014-2015 period. Practically, we analyse and compare the results of the following four different simulations: the latest reanalysis product for the Mediterranean Sea, a recently evaluated fine-resolution atmosphere-ocean Adriatic Sea climate model, and a long-time-running Adriatic Sea atmosphere-ocean forecast model used in both hindcast and data assimilation (with 4 d cycles) modes. As a first step, we evaluate the resolved physics in each simulation by focusing on the performance of the models. Then, we derive the general conditions in the ocean and the atmosphere during the investigated period. Finally, we analyse in detail the numerical reproduction of the dense-water dynamics as seen by the four simulations. The likely prerequisites for proper modelling of the ocean circulation in the Adriatic basin, including a kilometre-scale atmosphere-ocean approach, nonhydrostatic atmospheric models, fine vertical resolutions in both atmosphere and ocean, and the location and forcing of the open boundary conditions, are thus discussed in the context of the different simulations. In conclusion, a 31-yearlong run of the fine-resolution Adriatic Sea climate model is found to be able to outperform most aspects of the reanalysis product, the short-term hindcast, and the data-assimilated simulation in reproducing the dense-water dynamics in the Adriatic Sea.
In this evaluation study, the coupled atmosphereocean Adriatic Sea and Coast (AdriSC) climate mod... more In this evaluation study, the coupled atmosphereocean Adriatic Sea and Coast (AdriSC) climate model, which was implemented to carry out 31-year evaluation and climate projection simulations in the Adriatic and northern Ionian seas, is briefly presented. The kilometre-scale AdriSC atmospheric results, derived with the Weather Research and Forecasting (WRF) 3 km model for the 1987-2017 period, are then thoroughly compared to a comprehensive publicly and freely available observational dataset. The evaluation shows that overall, except for the summer surface temperatures, which are systematically underestimated, the AdriSC WRF 3 km model has a far better capacity to reproduce surface climate variables (and particularly the rain) than the WRF regional climate models at 0.11 • resolution. In addition, several spurious data have been found in both gridded products and in situ measurements, which thus should be used with care in the Adriatic region for climate studies at local and regional scales. Long-term simulations with the AdriSC climate model, which couples the WRF 3 km model with a 1 km ocean model, might thus be a new avenue to substantially improve the reproduction, at the climate scale, of the Adriatic Sea dynamics driving the Eastern Mediterranean thermohaline circulation. As such it may also provide new standards for climate studies of orographically developed coastal regions in general.
This numerical work aims to better understand the behavior of extreme Adriatic Sea wave storms un... more This numerical work aims to better understand the behavior of extreme Adriatic Sea wave storms under projected climate change. In this spirit, 36 characteristic events-22 bora and 14 sirocco storms occurring between 1979 and 2019, were selected and ran in evaluation mode in order to estimate the skill of the kilometer-scale Adriatic Sea and Coast (AdriSC) modelling suite used in this study and to provide baseline conditions for the climate change impact. The pseudo-global warming (PGW) methodology-which imposes an additional climatological change to the forcing used in the evaluation simulations, was implemented, for the very first time, for a coupled ocean-wave-atmosphere model and used to assess the behavior of the selected storms under Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 greenhouse gas projections. The findings of this experiment are that, on the one hand, the AdriSC model is found capable of reproducing both the Adriatic waves associated with the 36 storms and the northern Adriatic surges occurring during the sirocco events and, on the other hand, the significant wave heights and peak periods are likely to decrease during all future extreme events but most particularly during bora storms. The northern Adriatic storm surges are in consequence also likely to decrease during sirocco events. As it was previously demonstrated that the Adriatic extreme wind-wave events are likely to be less intense in a future warmer climate, this study also proved the validity of applying the PGW methodology to coupled ocean-wave-atmosphere models at the coastal and nearshore scales.
This study aims to enhance our understanding of the bora-driven dense-water dynamics in the Adria... more This study aims to enhance our understanding of the bora-driven dense-water dynamics in the Adriatic Sea using different state-of-the-art modelling approaches during the 2014-2015 period. Practically, we analyse and compare the results of the following four different simulations: the latest reanalysis product for the Mediterranean Sea, a recently evaluated fine-resolution atmosphere-ocean Adriatic Sea climate model, and a long-time-running Adriatic Sea atmosphere-ocean forecast model used in both hindcast and data assimilation (with 4 d cycles) modes. As a first step, we evaluate the resolved physics in each simulation by focusing on the performance of the models. Then, we derive the general conditions in the ocean and the atmosphere during the investigated period. Finally, we analyse in detail the numerical reproduction of the dense-water dynamics as seen by the four simulations. The likely prerequisites for proper modelling of the ocean circulation in the Adriatic basin, including a kilometre-scale atmosphere-ocean approach, nonhydrostatic atmospheric models, fine vertical resolutions in both atmosphere and ocean, and the location and forcing of the open boundary conditions, are thus discussed in the context of the different simulations. In conclusion, a 31-yearlong run of the fine-resolution Adriatic Sea climate model is found to be able to outperform most aspects of the reanalysis product, the short-term hindcast, and the data-assimilated simulation in reproducing the dense-water dynamics in the Adriatic Sea.
<p>Meteotsunami events – tsunami-like ocean waves driven by atmospher... more <p>Meteotsunami events – tsunami-like ocean waves driven by atmospheric disturbances – are, by nature, rare, specific to certain geographical regions and highly variable in time. Consequently, the coastal hazards due to these types of events are known to be difficult to forecast with state-of-the art numerical models presently applied around the world.</p> <p>In order to help the local communities to better prepare for these destructive events (e.g., set temporary protection against flooding and waves, avoid swimming, etc.) and minimize the losses, the Croatian Meteotsunami Early Warning System (CMeEWS) has been recently implemented in the Adriatic Sea in the testing mode. The CMeEWS is mostly based on the Adriatic Sea and Coast (AdriSC) modelling suite and uses an innovative deterministic-stochastic approach for extreme sea-level event predictions. It provides meteotsunami hazard forecasts depending on (1) daily deterministic forecasts by coupled kilometer-scale atmosphere-ocean models, (2) atmospheric observations and (3) stochastic forecasts of extreme sea-level distributions at endangered locations derived with a surrogate model approach. Some of these steps require substantial computational resources and needs an optimized data flow which, at end, defines the operability of the service.</p> <p>Here, the advantages but also the drawbacks of such an approach will be presented through several applications of the AdriSC modelling suite during meteotsunami events in the Adriatic Sea. The future challenges concerning meteotsunami extreme sea-level modelling will be discussed and some potential avenues to further develop the model skills will be considered.</p>
In this study, the Adriatic Sea and Coast (AdriSC) kilometre-scale atmosphere-ocean climate model... more In this study, the Adriatic Sea and Coast (AdriSC) kilometre-scale atmosphere-ocean climate model covering the Adriatic Sea and northern Ionian Sea is presented. The AdriSC ocean results of a 31-year-long (i.e. 1987-2017) climate simulation, derived with the Regional Ocean Modeling System (ROMS) 3 km and 1 km models, are evaluated with respect to a comprehensive collection of remote sensing and in situ observational data. In general, it is found that the AdriSC model is capable of reproducing the observed sea surface properties, daily temperatures and salinities, and the hourly ocean currents with good accuracy. In particular, the AdriSC ROMS 3 km model demonstrates skill in reproducing the main variabilities of the sea surface height and the sea surface temperature, despite a persistent negative bias within the Adriatic Sea. Furthermore, the AdriSC ROMS 1 km model is found to be more capable of reproducing the observed thermohaline and dynamical properties than the AdriSC ROMS 3 km model. For the temperature and salinity, better results are obtained in the deeper parts than in the shallow shelf and coastal parts, particularly for the surface layer of the Adriatic Sea. The AdriSC ROMS 1 km model is also found to perform well in reproducing the seasonal thermohaline properties of the water masses over the entire Adriatic-Ionian domain. The evaluation of the modelled ocean currents revealed better results at locations along the eastern coast and especially the northeastern shelf than in the middle eastern coastal area and the deepest part of the Adriatic Sea. Finally, the AdriSC climate component is found to be a more suitable modelling framework to study the dense water formation and long-term thermohaline circulation of the Adriatic-Ionian basin than the available Mediterranean regional climate models.
Journal Of Geophysical Research: Atmospheres, Feb 26, 2021
In process‐oriented studies, accurate representation of severe bora rotor dynamics in the norther... more In process‐oriented studies, accurate representation of severe bora rotor dynamics in the northern Adriatic is known to require the use of model resolutions of the order of 100 m. In regional climate studies, computation time and numerical cost are, however, minimized with resolutions of the order of 10 km. The latter is not accurate enough to drive the coastal dense water formation and the long‐term Adriatic‐Ionian thermohaline circulation resulting from these events. This work leverages the capacity of kilometer‐scale atmospheric models to balance accuracy and efficiency in coupled atmosphere‐ocean climate studies in the Adriatic Sea. The sensitivity of severe bora dynamics and air‐sea interactions to atmospheric model resolution is thus tested within the Adriatic Sea and Coast (AdriSC) modeling suite as well as with the best available reanalysis. The Weather Research and Forecasting (WRF) model at 15‐km, 3‐km, and 1.5‐km resolution, and ERA5 at 30‐km resolution, are compared for an ensemble of 22 severe bora storms spanning between 1991 and 2019. It is found that (1) ERA5 reanalysis and WRF 15‐km model highly diverge (up to 43% for the wind speed) from WRF 3‐km results while (2) WRF 3‐km conditions converge toward the WRF 1.5‐km solution for both basic bora dynamics (differences below 6% for the wind speed) and air‐sea interactions (differences 5 times smaller than with WRF 15‐km results). Consequently, kilometer‐scale atmospheric models should be used to reproduce properly the dense water formation during severe bora events and the long‐term thermohaline circulation of the Adriatic‐Ionian basin.
In engineering studies, harbor resonance, including quality and amplification factors, is typical... more 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.
. Due to on-going global warming, extreme storm surges are expected to threaten a greater number ... more . Due to on-going global warming, extreme storm surges are expected to threaten a greater number of coastal communities worldwide. However, global and regional climate simulations of extreme events are still not accurate enough to respond to the growing needs of the local decision makers to prepare for these rising hazards. We present a new approach using (sub-)kilometre-scale coupled atmosphere-ocean-wave models and demonstrate the feasibility to provide meter-scale assessments of the impact of climate change on storm surge hazards. As a proof of concept, we focus in the Adriatic Sea and analyse the sea levels of two kilometre-scale 31-year long simulations used in evaluation and extreme warming modes. First, we demonstrate that, at 1-km resolution, the model errors are reduced by up to a third compare to state-of-the-art regional and global models. Second, we show that meter-scale storm surge results – obtained by further downscaling extreme events extracted from the kilometre-scale simulations – contrast with the previously published literature. In particular, we found that some understudied regions of the Adriatic coast might be more vulnerable to sea level rise and atmospherically driven storm surges induced by extreme climate warming than the well-researched Venice Lagoon. Following these preliminary results, we present a newly developed methodology directly downscaling extreme events from global climate models. Within this framework, the numerical resources, previously spent to produce long-term simulations, are used efficiently to quantify the climate change uncertainty and to properly assess the meter-scale storm surge hazards.
In this study, the Adriatic Sea and Coast (AdriSC) kilometre-scale atmosphere-ocean climate model... more In this study, the Adriatic Sea and Coast (AdriSC) kilometre-scale atmosphere-ocean climate model covering the Adriatic and northern Ionian Seas is presented. The AdriSC ocean results of a 31-year long (i.e. 1987-2017) climate simulation, derived with the Regional Ocean Modeling System (ROMS) 3-km and 1-km models, are evaluated with respect to a comprehensive collection of remote-sensing and in situ observational data. In general, it is found that the AdriSC model is capable to reproduce the observed sea-surface properties, daily temperatures and salinities and the hourly ocean currents with good accuracy. In particular, the AdriSC ROMS 3-km model demonstrates skill in reproducing the main variabilities of the sea-surface height as well as the sea-surface temperature, despite a persistent negative bias within the Adriatic Sea. Furthermore, the AdriSC ROMS 1-km model is found to be more capable to reproduce the observed thermohaline and dynamical properties than the AdriSC ROMS 3-km model. For the temperature and salinity, better results are obtained in the deeper parts than in the shallow shelf and coastal parts, particularly for the surface layer of the Adriatic Sea. The AdriSC ROMS 1-km model is also found to perform well in reproducing the seasonal thermohaline properties of the water masses over the entire Adriatic-Ionian domain. The evaluation of the modelled ocean currents revealed better results at locations along the eastern coast and especially the northeastern shelf than in the middle-eastern coastal area and the deepest part of the Adriatic Sea. Finally, the AdriSC climate component is found to be a more suitable modelling framework to study the dense water formation and long-term thermohaline circulation of the Adriatic-Ionian basin than the available Mediterranean regional climate models. 1 Introduction Due to the temporal and spatial sparsity of the in situ observations, the study of the dynamics and variability of the ocean processes mostly relies on the constant developments and improvements of the available numerical modelling tools. Over the years, in the Adriatic Sea, significant progresses have thus been made by the ocean modelling community to overcome the challenges posed by the complex geomorphology of the region (Figs. 1.a and 1.b): (1) an extremely complex coastline with
Bulletin of the American Meteorological Society, 2023
Worldwide tsunamis driven by atmospheric waves-or planetary meteotsunami waves-are extremely rare... more Worldwide tsunamis driven by atmospheric waves-or planetary meteotsunami waves-are extremely rare events. They mostly occur during supervolcano explosions or asteroid impacts capable to generate atmospheric acoustic-gravity waves including the Lamb waves that can circle the globe multiple times. Recently, such ocean waves have been globally recorded after the Hunga Tonga-Hunga Ha'apai volcano eruption on 15 January 2022, but did not pose any serious danger to the coastal communities. However, this study highlights that the mostly ignored destructive potential of planetary meteotsunami waves can be compared to the well-studied tsunami hazards. In practice, several process-oriented numerical experiments are designed to force a global ocean model with the realistic atmospheric response to the Hunga Tonga-Hunga Ha'apai event rescaled in speed and amplitude. These simulations demonstrate that the meteotsunami surges can be higher than 1 m (and up to 10 m) along more than 7% of the world coastlines. Planetary meteotsunami waves thus have the potential to cause serious coastal damages and even human casualties during volcanic explosions or asteroid impacts either releasing intense acoustic energy or producing internal atmospheric gravity waves triggering the deep-ocean Proudman resonance at a speed of ~212 m s −1. Based on records of catastrophic events in Earth's history, both scenarios are found to be realistic, and consequently, the global meteotsunami hazards should now be properly assessed to prepare for the next big volcanic eruption or asteroid impact even occurring inland.
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