No abstract

At the present time, ocean current is being operationally monitored mainly by combined use of numerical ocean nowcast/forecast models and satellite remote sensing data. Improvement in the accuracy of the ocean current nowcast/forecast requires additional measurements with higher spatial and temporal resolution as expected from the current observation network. Here we show feasibility of assimilating high-resolution seabird and ship drift data into an operational ocean forecast system. Data assimilation of geostrophic current contained in the observed drift leads to refinement in the gyre mode events of the Tsugaru warm current in the north-eastern sea of Japan represented by the model. Fitting the observed drift to the model depends on ability of the drift representing geostrophic current compared to that representing directly wind driven components. A preferable horizontal scale of 50 km indicated for the seabird drift data assimilation implies their capability of capturing eddies with smaller horizontal scale than the minimum scale of 100 km resolved by the satellite altimetry. The present study actually demonstrates that transdisciplinary approaches combining bio-/ship- logging and numerical modeling could be effective for enhancement in monitoring the ocean current.

No abstract

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 firstorder 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.

The National Maritime Resea【ch Institute has conducled the research and development on " the environr lental fhendly shipping support system fbr coastal vessels " suppOrted by NEDO using actual cement tanker and RORO ship coopelate with ship ' s owncrs 、 The present study des α ibes a practical methodology on the sh 負 p ' s log speed estimated by analyzing accumulated actual navigadon data of coastal vessels ． The estimated values are checked by the relative veiocity with respecuo water derived from propeller analysis using measured