Articles | Volume 17, issue 3
Research article
27 Mar 2017
Research article |  | 27 Mar 2017

Time clustering of wave storms in the Mediterranean Sea

Giovanni Besio, Riccardo Briganti, Alessandro Romano, Lorenzo Mentaschi, and Paolo De Girolamo

Abstract. In this contribution we identify storm time clustering in the Mediterranean Sea through a comprehensive analysis of the Allan factor. This parameter is evaluated from a long time series of wave height provided by oceanographic buoy measurements and hindcast reanalysis of the whole basin, spanning the period 1979–2014 and characterized by a horizontal resolution of about 0.1° in longitude and latitude and a temporal sampling of 1 h Mentaschi et al. (2015). The nature of the processes highlighted by the AF and the spatial distribution of the parameter are both investigated. Results reveal that the Allan factor follows different curves at two distinct timescales. The range of timescales between 12 h to 50 days is characterized by a departure from the Poisson distribution. For timescales above 50 days, a cyclic Poisson process is identified. The spatial distribution of the Allan factor reveals that the clustering at smaller timescales is present to the north-west of the Mediterranean, while seasonality is observed across the whole basin. This analysis is believed to be important for assessing the local increased flood and coastal erosion risks due to storm clustering.

Short summary
Results of 36-years of hindcast in the Mediterranean Sea are analysed to detect time clustering of wave storms using the Allan factor. The analysis reveals that some areas of the basin are characterized by storm clustering for timescales t < 50 days, while seasonality is dominant at large scales. The findings highlight a deviation from the Poisson distribution in some sub-basins of the Mediterranean Sea. Implications for coastal erosion/flooding need to be studied further.
Final-revised paper