Seasonal forecasting of winds, waves and currents in the North Pacific

Abstract

ABSTRACTThis study assesses the skill of seasonal forecasts for the environmental variables of surface wind speed, ocean surface current speed and significant wave height in the North Pacific. The ultimate goal is to use the forecasts for vessel routing. The surface wind speed and ocean surface current speed is taken from retrospective forecasts for the period of 1982–2015 using the Community Climate System Model 4. The wave data are obtained from a WAVEWATCH III experiment forced with winds and currents. Several lead time forecasts are investigated from 0–6 months, resulting in a total of 2720 years. This ensures that the findings from this study are robust. July is the most benign month in the North Pacific and is used as the target forecast. July surface wind speed and significant wave height are shown to be predictable, with the western North Pacific being the most predictable region. Beyond a lead time of 2 months, the forecast skill of significant wave height decreases. However, there is skill for July surface wind speed with initial conditions for January (lead time of 6 months). This study shows that there is potential to use seasonal forecast data for vessel routing, in particular, in the Tropics.Abbreviations: CCSM4: Community Climate System Model 4; CFSR: Climate Forecast System Reanalysis; ENSO: El Niño Southern Oscillation; ECMWF: European Centre for Medium-Range Weather Forecasts; ERA-Interim: ECMWF Interim Re-Analysis; ERS: European Remote Sensing; GFO: GEOSAT Follow-ON; Hs: Significant wave height; JCOMM: Joint Technical Commission for Oceanography and Marine Meteorology; LCS: Littoral Combat Ship; NCEP: National Centers for Environmental Prediction; NEMO: Nucleus for European Modelling of the Ocean; P90: 90th percentile; PDO: Pacific Decadal Oscillation; PMM: Pacific Meridional Model; ORAP5: ECMWF Ocean Re-Analysis Pilot 5; RMSE: Root Mean Square Error; ROC: Relative Operating Characteristics; RPS: Ranked Probability Score; RPSS: Ranked Probability Skill Score; SARAL: Satellite with ARgos and ALtiKa; SSALTO/DUACS: Segment Sol Multimissions d’Altimétrie, d’Orbitographie et de Localisation Précise of the Data Unification and Altimeter Combination; WAM: Wave Assimilation Model; WW3: WAVEWATCH III