Characterisation of low-frequency sea level oscillations in the Mediterranean sea
- Authors: Vesna Bertoncelj, Matjaž Ličer, Dušan Žagar, Davide Bonaldo
- Citation: Acta hydrotechnica, vol. 32, no. 57, pp. 121-133, 2019. https://doi.org/10.15292/acta.hydro.2019.09
- Abstract: Implementing adequate defences for low-lying coastal area against coastal flooding requires thorough knowledge of all potential influences leading to increased sea levels, including low-frequency sea level oscillations. We present and describe several methods applicable for the analysis of low-frequency sea level oscillations in the Mediterranean Sea: wavelet analysis, spectral analysis, moving-periodogram analysis, and rotary spectral analysis. These methods were applied for characterisation of subinertial sea level oscillations with periods greater of the period of inertial oscillation (18 hours in the Northern Adriatic Sea) on measured sea surface elevations and current velocities in the Mediterranean Sea. Preliminary analysis was performed on observations of a storm event in the Adriatic Sea at the end of January and the beginning of February 2014, revealing a peak in the frequency spectrum in the frequency band between 0.3−0.4 day−1. Further analysis was done on long-term tide gauge measurements available for 62 stations in the Mediterranean basin. The application of the selected methods provided a preliminary set of seasonal occurrences and durations of subinertial oscillation. This sets the ground for further investigation into the propagation of low-frequency sea level oscillations throughout the Mediterranean basin and for characterisation of the mechanisms triggering the process, including with regard to climate change.
- Keywords: sea level oscillations, subinertial oscillations, Adriatic Sea, Mediterranean Sea, wavelet analysis, spectral analysis, moving periodogram
- Full text: a32vb.pdf
- References:
- Archetti, R., Paci, A., Carniel, S., Bonaldo, D. (2016). Optimal index related to the shoreline dynamics during a storm: The case of Jesolo beach. Natural Hazards and Earth System Sciences, 16(5), 1107–1122. https://10.5194/nhess-16-1107-2016.
- Bertoncelj, V. (2018). Low-frequency sea level oscillations in the Mediterranean Sea. Unpublished thesis, University of Ljubljana, Faculty of Civil and Geodetic Engineering.
- Bonaldo, D., Orlić, M., Carniel, S. (2018). Framing Continental Shelf Waves in the southern Adriatic Sea, a further flushing factor beyond dense water cascading. Scientific Reports, 8(1), 660. https://10.1038/s41598-017-18853-2.
- Candela, J., Lozano, C. J. (1994). Barotropic Response of the Western Mediterranean to Observed Atmospheric Pressure Forcing. The Seasonal and Interannual Variability of the Western Mediterranean Sea, Coastal and Estuarine Studies, 46, 325–359. https://10.1029/CE046.
- Clementi, E., Pistoia, J., Escudier, R., Delrosso, D., Drudi, M., Grandi, A., Pinardi, N. (2019). Mediterranean Sea Analysis and Forecast (CMEMS MED-Currents 2016-2019) (Version 1). Copernicus Monitoring Environment Marine Service (CMEMS). doi: https://doi.org/10.25423/CMCC/MEDSEA_ANALYSIS_FORECAST_PHY_006_013_EAS5.
- Cushman-Roisin, B., Gačić, M., Poulain, P.-M., Artegiani, A. (2001). Physical Oceanography of the Adriatic Sea. Springer-Science+Business Media, B.V. https://10.1007/978-94-015-9819-4.
- Dukhovskoy, D. S., Morey, S. L., O’Brien, J. J. (2009). Generation of baroclinic topographic waves by a tropical cyclone impacting a low-latitude continental shelf, Continental Shelf Research, 29(1), 333–351. https://10.1016/j.csr.2008.01.007.
- Emery, W. J., Thomson, R. E. (2001). Data analysis methods in physical oceanography. p. 612.
- Falcieri, F. M., Kantha, L., Benetazzo, A., Bergamasco, A., Bonaldo, D., Barbariol, F., Malačič, V., Sclavo, M., Carniel, S. (2016). Turbulence observations in the Gulf of Trieste under moderate wind forcing and different water column stratification. Ocean Science, 12(2), 433–449. https://10.5194/os-12-433-2016.
- Gomis, D., Ruiz, S., Sotillo, M. G., Álvarez-fanjul, E., Terradas, J. (2008). Low frequency Mediterranean sea level variability: The contribution of atmospheric pressure and wind. Global and Planetary Change journal, 63, 215–229. https://10.1016/j.gloplacha.2008.06.005.
- Gomis, D., Tsimplis, M., Marcos, M. (2012). The Climate of the Mediterranean Region: Mediterranean Sea-Level Variability and Trends. https://10.1016/B978-0-12-416042-2.00004-5.
- Heinzel, G., Rüdiger, a, Schilling, R., Hannover, T. (2002). Spectrum and spectral density estimation by the Discrete Fourier transform (DFT), including a comprehensive list of window functions and some new flat-top. Max Plank Institute, 1–84. https://395068.0.
- Holthuijsen, L. H. (2007). Waves in oceanic and coastal waters. Cambridge University Press. https://10.1017/CBO9780511618536.
- Pirazzoli, P. A., Tomasin, A. (2002). Recent Evolution of Surge-related Events in the Northern Adriatic Area. Journal of Coastal Research, 18(3), 537–554. https://10.4000/mediterranee.174.
- Schwab, D. J., Rao, D. B. (1983). Barotropic oscillations of the Mediterranean and Adriatic Seas. Tellus, 35A(5), 417–427. https://10.1111/j.1600-0870.1983.tb00216.x.
- Sektor za analize in prognoze površinskih voda, Urad za hidrologijo in stanje okolja (2014). Hidrološko poročilo o visokih vodah v dneh med 30 . januarjem in 3 . februarjem 2014 (Hydrological report on high waters between 30 January and 3 February 2014). pp. 1–8.
- Šepic, J., Vilibic, I., Lafon, A., Macheboeuf, L., Ivanovic, Z. (2015). High-frequency sea level oscillations in the Mediterranean and their connection to synoptic patterns. Progress in Oceanography journal, 137, 284–298. https://10.1016/j.pocean.2015.07.005.
- Thompson, R. O. R. Y., Luyten, J. R. (1976). Evidence for bottom-trapped topographic Rossby waves from single moorings. Deep Sea Research and Oceanographic Abstracts, 23(7), 629–635. https://10.1016/0011-7471(76)90005-X.
- Thomson, R. E., Emery, W. J. (2014). Data Analysis Methods in Physical Oceanography. Elsevier. https://10.1016/C2010-0-66362-0.
- USACE (2002). Coastal Engineering Manual. Engineer Manual 1110-2-1100. Washington, USA.: U.S. Army Corps of Engineers.
- Vilibić, I., Šepić, J., Pasarić, M., Orlić, M. (2017). The Adriatic Sea: A Long-Standing Laboratory for Sea Level Studies. Pure and Applied Geophysics. https://10.1007/s00024-017-1625-8.
- Welch, P. D. (1967). The use of fast Fourier transform for the estimation of power spectra: A method based on time averaging over short, modified periodograms. IEEE Transactions on Audio and Electroacoustics, 15(2), 70–73. https://10.1109/TAU.1967.1161901.