Stochastic Surrogate Model for Meteotsunami Early Warning System in the Eastern Adriatic Sea

Abstract

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.

Performance of the Adriatic early warning system during the multi-meteotsunami event of 11–19 May 2020: an assessment using energy banners

“…The Croatian Meteotsunami Early Warning System (CMeWS) receives three different kind of data: (1) high-resolution atmospheric and ocean model results provided by the Adriatic Sea and Coast (AdriSC) modelling suite (Denamiel et al, 2019a), (2) measurements from the MESSI (www.izor.hr/messi) observational network along the Adriatic coast and 3meteotsunami hazard assessments based on the stochastically estimated maximum elevation distributions derived from a meteotsunami surrogate model (Denamiel et al, 2019b(Denamiel et al, , 2020.…”

“…In this deterministic configuration, the ADCIRC model is forced every minute by the WRF 1.5-km wind and pressure fields, and every hour by the basic module sea-level fields (including tides). In operational mode (Denamiel et al, 2019a(Denamiel et al, , 2019b the AdriSC modelling suite runs every day with the basic module initial state and boundary conditions provided by (1) the previous day 12 UTC based analysis of the ECMWF 10-day forecast model (HRES at 0.1° resolution; Zsótér et al, 2014) for the atmosphere and (2) the Mediterranean Forecasting System (MFS/MEDSEA at 1/24° resolution; Pinardi et al, 2003) for the ocean. At midnight, the next 48 h hourly-forecast results from the basic module, as well as the 15 min-forecast results from the meteotsunami module for the next day, are published at http://www.izor.hr/adrisc.…”

“…Vela Luka, Stari Grad and Vrboska). To bridge such a problem, the meteotsunami stochastic surrogate model, used to propagate the uncertainties of the atmospheric disturbances to the meteotsunami waves, was thus developed within the CMeEWS (Denamiel et al, 2019b(Denamiel et al, , 2020.…”

“…meteotsunamis may occur) of the CMeEWS is triggered for all the days of the 11-19 May 2020 period (except the 12 th and 13 th when model results are not available). Following Denamiel et al (2019b), the event mode is triggered when the spatial coverage of the maximum temporal rate of change of the high-pass filtered air pressure, derived at each WRF 1.5-km grid sea point, are greater than 5 % ( Fig. S1 provided as supplementary material).…”

“…In the United States, meteotsunami early warning systems are still under development by the NOAA (National Oceanic and Atmospheric Administration) and will be based on high-resolution air pressure measurements combined with forecast models (Anderson et al, 2020). Finally, the recently developed Croatian Meteotsunami Early Warning System (CMeEWS) is based on an observational network of pressure sensors and tide gauges, as well as on the deterministic AdriSC modelling suite (Denamiel et al, 2019a) and the stochastic meteotsunami surrogate model (Denamiel et al, 2019b(Denamiel et al, , 2020. It provides meteotsunami hazard assessments depending on forecasted and measured https://doi.org/10.5194/nhess-2020-409 Preprint.…”