Integration of Weather Research and Forecasting (WRF) model with regional coastal ecosystem model to simulate the hypoxic conditions.

Regional ocean models require accurate weather data for atmospheric boundary conditions such as air temperature, wind speed, and direction to simulate the coastal environment. In this study, a numerical modelling framework was developed to simulate different physical, chemical, and biological processes in a semi-enclosed coastal ecosystem by integrating the Weather Research and Forecasting (WRF) model with a 3D hydrodynamic and ecosystem model (Ise Bay Simulator). The final analytic data of the global forecast system released by the National Centers for Environmental Prediction with a 0.25° horizontal resolution was used as an atmospheric boundary condition for the WRF model to dynamically downscale the weather information to a spatial and temporal fine resolution. This modelling framework proved to be an effective tool to simulate the physical and biogeochemical processes in a semi-enclosed coastal embayment. The WRF-driven ecosystem simulation and recorded Automated Meteorological Data Acquisition System (AMeDAS)-driven ecosystem simulation results were further compared with the observed data. The performance of both the recorded AMeDAS and WRF generated weather datasets were equally good, and more than 80% of the variation in bottom dissolved oxygen for shallow water and more than 90% for deep water was reproduced.

In situ estimates of horizontal turbulent diffusivity at the sea surface for oil transport simulation.

Despite many previous in situ estimates of horizontal diffusivity below the sea surface, horizontal diffusivity at the sea surface, which is a parameter required in the prediction of oil diffusion, has not been formulated. This study conducted in situ estimations to quantify horizontal diffusivity at the sea surface. To measure the horizontal diffusivity at and below the sea surface, clusters of thin sponge rubbers (simulating spilled oil), together with drifting buoys, were deployed on successive occasions in Sagami Bay, Japan. The experimental results revealed that horizontal diffusivity was larger at the sea surface than below. Based on the results, a procedure for estimating horizontal diffusivity at the sea surface was introduced to predict the diffusion of spilled oil, which was verified using numerical simulations. The simulation results showed good agreement with observations, suggesting the procedure is appropriate for the estimation of horizontal diffusivity at the sea surface.