Fig nbsp xA Effect of wave forces on the

The tidal model was validated at several tidal gauge stations within the Irish Sea. The validation results relatively near to the site CAL-101 presented here. ADCP (acoustic Doppler current profiler) data collected during August 2013, at Holyhead Deep (ADCP1, Fig. 1a), and February 2014, off the northern coast of Anglesey (ADCP2, Fig. 1a), were used for current validation. Fig. 4a shows the comparison of model outputs and observed data at Holyhead tidal gauge. Table 2 also shows the performance of the model for water elevation and current velocity. The mean absolute error, which is reported in Table 2, is defined as.equation(4)MAE=1M∑i=1M uco(i)−ucm(i) where M   is the number of data points, uco and ucm are observed and predicted values of depth averaged velocities, respectively. The current ellipses for M2 and S2 based on the model results and observations have also been compared in Fig. 4b. The model error for M2 and S2 amplitudes were 5 cm and 8 cm, and for phases were 2° and 1°, respectively. For ADCP1, the errors of the current ellipse axes directions were 7° and 8° for M2 and S2 while less than 2% for magnitudes of the ellipses major axis. The small error in tidal ellipse directions may be associated with the 3-D nature of the flow [40] at archaeocyathids location, which is deeper than the surrounding areas. Similar discrepancies for current velocities have been reported in a previous study of the region which used ADCIRC depth averaged model [12]. Similar results can be seen for ADCP2. The mean absolute error of current velocity for two measurement locations is less than 0.20 m/s. Overall, given the magnitudes of the errors, model performance for both tidal elevations and currents is convincing.