Rough wave simulation and validation using onboard ship motion data in the Southern Hemisphere to enhance ship weather routing

In this study, three cases of rough-sea navigation in the Southern Hemisphere were reproduced using the National Oceanic and Atmospheric Administration's WAVEWATCH III. Different wind inputs with various spatial and temporal resolutions were considered, originating from the National Centers for Environmental Prediction Final (NCEP-FNL) Operation Model Global Tropospheric Analyses, the European Center for Medium-range Weather Forecasts Interim Reanalysis (ERA-Interim), and the Weather Research and Forecasting (WRF) model. The simulated waves (wave hindcasts) were validated using measured onboard ship motion data. Comparisons of measured and simulated pitch motion indicated that each of the different wind inputs produced reasonable first-order estimates of rough waves. However, for application to a ship's weather routing systems, wind input selection should be carefully considered. For example, near-surface winds from the ERA-Interim underestimated rough waves, while those from the NCEP-FNL Analyses had a contrary tendency. In addition, although the wind inputs from the ERA-Interim produced wave hindcasts that is more consistent with measured results, these same inputs generally underestimated the increasing-phase pitch motion under severe weather conditions, which poses a danger for ships. Thus, the use of wind inputs from NCEP-FNL Analyses or higher-resolution WRF model is recommended for application to ship weather routing systems.