Analysing trends of surface waves and currents within Maltese territorial waters

Abstract

The dynamic nature of water bodies encourages room for research on current and changing trends across different areas. The Mediterranean Sea serves as a passage for a large percentage of vessels, and the Maltese harbour welcomes many of these. Moreover, with the Blue Growth and Blue Economy targets set for Malta, marine traffic in the areas is expected to increase. Therefore, the goal of this research is to analyse the surface currents and waves in Maltese territorial waters. The satellite, model, and in-situ data that was analysed revealed trends and changing dynamics. Data between November 2019 and November 2021 was considered, and the results focused on surface currents magnitude, wave height and wave direction from four different datasets extracted from the Marine Copernicus Service. Custom MATLAB scripts were implemented to produce clusters and groups to determine any changes in the typical seasons and any abnormal variations. Self-Organising Maps (SOM) were used. This unsupervised Machine Learning method allowed similar values within each zone to be grouped. Moreover, using image segmentation and the K-means algorithm, the ROI was also automatically divided into zones. The results obtained for the wave height and currents trends were compared to existing literature. Autumn and winter months were found to exhibit higher wave heights than spring and summer ones. The magnitude of sea surface currents also proved to be stronger in the winter months and started to decrease around March. The automatic clustering of the data also indicated a possible shift in the typical seasons. Wind direction was not suitably divided into groups as direction can vary throughout the year and is not dependent on seasons or different months.