20 Oct 2022
20 Oct 2022
Status: this preprint is open for discussion.

Modelling the barotropic sea level in the Mediterranean using data assimilation

Marco Bajo1, Christian Ferrarin1, Georg Umgiesser1,2, Andrea Bonometto3, and Elisa Coraci3 Marco Bajo et al.
  • 1Institute of Marine Sciences, National Research Council, Castello 2737/F, 30122 Venice, Italy
  • 2Klaipeda University, Coastal Research and Planning Institute, H.Manto 84, 92294 Klaipėda, Lituania
  • 3Institute for Environmental Protection and Research, S. Marco, 4665, 30122 Venice, Italy

Abstract. This paper analyses the variability of the sea level in the Mediterranean Sea and its reproduction with a barotropic model, with and without applying data assimilation. The impact of data assimilation is considered in hindcast and forecast simulations, considering its usefulness for both reanalysis studies and short-term forecasts. We used a two-dimensional finite element barotropic model with an ensemble Kalman filter, assimilating hourly sea-level observations from 50 stations along all the Mediterranean coasts. The results show a great improvement given by data assimilation in hindcast simulations for the reproduction of astronomical tide, surge and total sea level, even in coastal areas far from the assimilated stations (e.g. the Eastern Mediterranean Sea). The improvement is consistent also in forecasts, especially for the first day (~37 % average error reduction), and in case of storm surge events with a strong presence of seiche oscillations. Since these oscillations depend only on the initial state and not on the boundary conditions, they are corrected very effectively by data assimilation. Finally, based on observations, this article estimates the periods of the normal barotropic modes (seiches) in the Adriatic Sea, where they have been extensively studied, and in the Mediterranean Sea, where the present documentation is scarce.

Marco Bajo et al.

Status: open (until 15 Dec 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-1126', Anonymous Referee #1, 13 Nov 2022 reply
  • RC2: 'Comment on egusphere-2022-1126', Anonymous Referee #2, 17 Nov 2022 reply

Marco Bajo et al.

Model code and software

SHYFEM model with data assimilation Marco Bajo et al.

SHYFEM model Georg Umgiesser et al.

Marco Bajo et al.


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Short summary
This work uses sea-level observations and a model to reproduce the sea level in the Mediterranean basin. We considered various components, due to astronomical and meteorological forcing. Furthermore, the periods of oscillation of the sea level of the Mediterranean Sea were studied. This research aims to improve sea level prediction to prevent flood events and improve sea level reproduction in past periods, for climatological or other studies.