Short-term spectral and statistical analysis of sea surface elevation data from buoys located in the greek seas

Περίληψη

Sea surface elevation is of great interest due to its impact on every-day activities such as tourism and shipping as well as the information it provides for various scientific fields. As Greece has its main socio-economic activities along its coastline, data that focus on the condition of its marine state are of significant importance. The Poseidon Marine Monitoring Network of HCMR has been used in order to monitor, forecast and provide information about sea conditions, with the use of offshore located buoys. For this research, sea surface elevation data from 5 buoys in the Aegean and Ionian Seas were analyzed, both statistically and spectrally using a script in MATLABs Toolbox WAFO (Wave Analysis for Fatigue and Oceanography) that was developed. The records covered a sampling period of 17mins (i.e., 1024 sec), repeated every 3hours and with a sampling frequency of 1 Hz. For this analysis, the waves were defined as consecutive down-crossings of the sea surface elevation at the mean sea level (i.e. 0 m). The following wave characteristics were calculated: wave steepness , wave height , wave period , crest amplitude , trough amplitude , crest front period and crest back period (rear) . From the analysis, the following results were provided for the Aegean and Ionian Seas: For the North Aegean, [...] The correlation between statistical and spectral wave characteristics had values of r-square approximately 0.9. Future work will include a more detailed analysis of sea surface elevation, to obtain information about characteristics of wind waves and swell, as well as, a relation of maximum values of wave height with potential extreme events.