DATE2022-05-25 10:16:53
TITLEMultiple drivers of extreme sea levels in the northern Adriatic Sea in the recent past
AUTHORSChristian Ferrarin (1) ,Piero Lionello (2) ,Mirko Orlić (3) ,Fabio Raicich (4) ,Gianfausto Salvadori (2)
  1. 1) Cnr-ismar, Venice (Italy) ,2) University Of Salento, Lecce (Italy) ,3) University Of Zagreb, Zagreb (Croatia) ,4) Cnr-ismar, Trieste (Italy)
ABSTRACTMany coastal locations are already experiencing an alarming growth of flood threat due to global warming and consequent rise of the level of the oceans. It is likely that within the next decades what we now consider to be extreme events will happen at every high tide. Extreme sea levels (ESLs) at the coast result from the combination of astronomical tides with atmospherically forced fluctuations at multiple time scales. Seiches, river floods, waves, inter-annual and inter-decadal dynamics and relative sea-level rise can also contribute to the total sea level. While tides are usually well described and predicted, the effect of the different atmospheric contributions to the sea level and their trends are still not well understood. Meso-scale atmospheric disturbances, synoptic-scale phenomena and planetary atmospheric waves act at different temporal and spatial scales and thus generate sea-level disturbances at different frequencies. In this study, we analyze tide-gauge time series, model reanalyses and climate simulations to investigate the relative role of the different driving factors in the extreme sea levels distribution in the recent past. The adopted approach consists in isolating the different contributions to the sea level by applying least-squares fitting and Fourier decomposition and evaluating the capacity of reanalysis and climate modelling in reproducing the observed variability. While storm surges are the main drivers of the most extreme events, tides and long-term forcing associated with planetary atmospheric waves and seasonal to inter-annual oscillations are predominant in determining recurrent nuisance flooding. Numerical models adequately capture the variability of the main ESL drivers in the northern Adriatic Sea, thus demonstrating that they can be used for predicting the future evolution of coastal flood risk. This work has been partially supported by the Interreg Italy-Croatia AdriaClim project (Climate change information, monitoring and management tools for adaptation strategies in Adriatic coastal areas; project ID 10252001).