Development of prediction system for drifting/diffusion of sea water, sea ice, and spilled oil in the Sea of Okhotsk

点击翻译按钮获取中文摘要

As the base of prediction for drifting/diffusion of sea water, sea ice and spilled oil in the Okhotsk Sea, 3-dimensional ocean model with the resolution of 1/6 degree was developed. The model is driven by daily wind stress and monthly heat flux. Comparison with surface drifter, moored ADCP, and ocean radar data shows that the model successfully reproduces the velocity field for the East Sakhalin Current (ESC) and Soya Warm Current. The turbulent velocities are represented by random-walk on the assumption of a Markov-chain model. A series of particle tracking experiments was carried out for the case that particles are released from the Sakhalin oil field at depths of 0 m and 15m. Regardless of the deployment month, most particles at depth 15 m are transported southward along the Sakhalin coast, in accordance with the abrupt intensification of the ESC in October, finally arriving offshore of Hokkaido. Particles at the surface, affected by wind drift in addition to the ocean current, show larger yearly variability. In offshoreward-wind dominant years, the particles would be advected out of the mainstream of the current and not be transported offshore of Hokkaido. The ESC is found to play important roles on drifting and spreading of the Amur origin contaminants. A backward-tracking experiment was performed to detect the origin of dead seabirds with oil beaching on the shores of Shiretoko Hokkaido in 2006, suggesting that these birds were transported from the north, possibly east Sakhalin coast via the ESC. Velocities from the tidal simulation model were also included in the particle tracking experiments to better represent the diffusivity. As for the sea ice prediction, the good prediction scheme for the maximum ice extent was developed, using air temperature in the northwest region and sea surface temperature off the Kamtchack Peninsula.