Event-based validation of swell arrival time

The arrival time of ocean swells is an important factor for offshore and coastal engineering and naval and recreational activities, which can also be used in evaluating the numerical wave model. Using the continuity and pattern of wave heights during the same swell event, a methodology is developed for identifying swell events and verifying swell arrival time in models from buoy data. The swell arrival time in a WAVEWATCH III hindcast database is validated with in situ measurements. The results indicate that the model has a good agreement with the observations but usually predicts an early arrival of swell, about 4 h on average. A histogram shows that about one-quarter of swell events arrive early and three-quarters late by comparison with the model. Many processes that may be responsible for the arrival time errors are discussed, but at this stage it is not possible to distinguish between them from the available data.