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Research on coastal ocean circulation patterns over long time periods is significant for various marine endeavors: environmental protection, coastal engineering construction, and marine renewable energy extraction. Based on sea surface current data remotely observed using a shore-based high frequency radar (HFR) system for one year (2016), spatiotemporal characteristics of surface flow fields of sea surface flow fields along the west coast of Ireland are studied using harmonic analysis, rotary spectral analysis and representative flow fields over different seasons and the whole year. Coastal surface currents in the study area are strongly affected by tidal dynamics of the M2 constituent, showing significant characteristics of regular semidiurnal tide, such as M2 and S2. The energy spectrum distribution indicates that the tidal constituents M2 and S2 are the dominant periodic energy constituents in a counterclockwise spectrum, which mainly presents rotating flow; the representative diurnal tidal constituents is the constituent K1, and its energy spectrum distribution is mainly clockwise. A comparison between probable maximum current velocity (PMCV) and measured maximum current velocity (MMCV) is presented. It shows that although tidal current characteristics in the study area are significant, the main driving force of the currents at the time of the maximum currents is wind energy. These results provide new insights into a region of huge societal potential at early stages of sustainable economic exploitation where few data currently exist. [ABSTRACT FROM AUTHOR]

Residual current characteristics are indicators for the net transports of sediments, nutrients, and pollutants, and for the dilution and diffusion of soluble substances in coastal areas, yet their driving mechanisms remain poorly understood. Here, we studied the characteristics of surface residual currents along the west coast of the island of Ireland, as well as the response mechanisms to wind at a seasonal scale based on the continuous observation data of high-frequency radar (HFR) for one year. Our analyses indicate that wind has a significant effect on generating surface residual currents, with correlation coefficients of 0.6–0.8 between wind speeds and residual current speeds at both annual and seasonal scales. However, the correlation between the directions of residual currents and the wind was not as significant as speed, likely because the directions of residual currents were not only affected by sea surface wind, but also by land boundary conditions in the research area. Moreover, the residual currents had a significant eastward flow trend identical to the wind direction at the maximum wind speed time, during which the effect of the tide on residual currents was relatively weak. Additionally, when compared with wind fields, HFR surface flow fields and surface residual current fields show that wind is the dominant driver of the variations of surface and residual flow fields. These findings shed light on coastal ecological and environmental management and can assist in the prevention and mitigation of marine disasters, by providing helpful information for improving the ability and accuracy of forecasting coastal currents. [ABSTRACT FROM AUTHOR]