Development of Nested Local Scale Wave Model for Storm Study in Brandon Bay Using SWAN

A numerical wave model has been developed for Brandon Bay on the west coast of Ireland to investigate storm wave conditions in the Bay. The model consists of a regional North-East Atlantic domain at a resolution of 0.05° and a nested local Brandon Bay domain resolved at 0.001° (approximately 110 m). The model uses freely available datasets. Wave boundary conditions for the regional model are retrieved from NOAA's global Wave-Watch III dataset, while those for the local model are supplied from the regional model. The wind input is from the NOAA-NECP global CCMP atmospheric dataset which was verified against measured data from a temporary local wind station in the study area. The regional model was calibrated against offshore buoys within the north-eastern Atlantic ocean for one month between May and June 2017. The local model was calibrated against AWAC measurement data for a similar period. During calibration, sensitivity tests were conducted for the domain size, wave growth formula, white capping formula, diffraction and wave breaking parameters. The calibrated models were finally validated against three months of measured data from January 2020 to February 2021. As a first step towards characterising storm conditions in the Bay, a hindcast for a one-year period (2020) was simulated. The wave outputs were used to analyse the storminess characteristics in the Bay.