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

建立了分辨率为1/6度的三维海洋模型，作为预测鄂霍次克海海水、海冰和溢油漂移/扩散的基础。模型由日风应力和月热通量驱动。与海面漂船、系泊ADCP和海洋雷达资料的比较表明，该模型成功地再现了东库页流（ESC）和大豆暖流的速度场。湍流速度在马尔可夫链模型的假设下用随机游走来表示。针对库页岛油田在0 m和15m深度释放颗粒的情况，进行了一系列颗粒跟踪实验。无论部署月份如何，15 m深度的大部分粒子沿库页岛海岸向南输送，最终到达北海道近海，与10月ESC的突然强化一致。地表粒子受风漂和洋流的影响，表现出较大的年变率。在近海风主导的年份，这些颗粒将被平流出主流，而不会被输送到北海道的近海。研究发现，ESC对阿穆尔河源污染物的漂移和扩散起着重要作用。2006年，在北海道石东海岸进行了一项回溯实验，以检测石油搁浅的死海鸟的来源，表明这些鸟是通过ESC从北部，可能是东部库页岛海岸运输过来的。在粒子跟踪实验中也加入了潮汐模拟模型的速度，以更好地代表扩散率。在海冰预测方面，利用西北地区的气温和坎察克半岛附近的海温，建立了较好的最大冰区预测方案。

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.