Study on actual behavior of mesoscale eddies in oceanic turbulence with satellite-image analysis and numerical simulation

黑潮、潮等洋流对日本岛链周边流场影响较大，以中尺度涡旋为特征，水平长度尺度为几百公里。虽然中尺度涡旋的行为与沿海环境密切相关，但中尺度涡旋的动力演变仍有许多未知因素。另一方面，本项目负责人利用NOAA极地轨道气象卫星的图像处理技术，监测海面水温和速度矢量的大尺度格局，并试图考察日本岛链周围的洋流结构和中尺度涡旋的实际运动。为了进一步发展上述研究，本项目研究了日本岛链周围流场中尺度涡旋的实际行为。在此基础上，我们尝试发展包括中尺度涡旋在内的海流的数值方法。本项目的主要成果如下：(1)基于卫星图像分析的海洋湍流测量利用NOAA/AVHRR热红外数据进行了海洋湍流可视化和海面速度测量。每天通过采集卫星数据对海洋湍流进行持续监测。结合上述卫星资料和其他已发表的海洋湍流资料，我们构建了日本岛链周围海洋湍流数据库。(2)采用新的嵌套方法进行海流模拟为了将上述实测海流数据有效地整合到海流模拟中，提出了一种新的海流模型嵌套程序，并将其应用到海流模拟中。通过计算结果与观测结果的比较，证实了本文方法的基本有效性。少

Ocean currents such as the Kuroshio and Oyashio, which strongly influence on the flow fields around Japan-Island-Chain, are characterized by the mesoscale eddies with the representative horizontal length scale of a few hundreds kilometers. Although the behaviors of the mesoscale eddies are closely related with the coastal environments, there are a number of unknown factors for the dynamical evolution of the mesoscale eddies. On the other hand, the head investigator in this project has been monitoring the large-scale patterns of the water temperature and velocity vectors on sea surfaces with the image processing for the polar orbiting meteorological satellite NOAA, and then attempted to examine ocean current structures and the actual motion of mesoscale eddies around Japan-Island-Chain. For further evolutions of the above study, in the present project, we investigate the actual behavior of mesoscale eddies in the flow fields around Japan-Island-Chain. Furthermore we try to develop the n … More umerical method of ocean current including the mesoscale eddies. The main results of the project are expressed in the followings.(1)Measurements for oceanic turbulence with the satellite-image analysisWe have conducted flow visualizations and sea-surface velocity measurements with NOAA/AVHRR thermal infrared data. Every day the monitoring of the oceanic turbulence has been continuously performed by capturing the satellite data. Combing the above satellite-based data and other published data concerning the oceanic turbulence, we have constructed the database for the oceanic turbulence around Japan-Island-Chain.(2)Ocean current simulations with a new nesting approachTo effectively incorporate the above measured ocean-current data on ocean current simulations, a new nesting procedure for ocean current model was developed and then applied to the ocean current simulation. Through the comparison of the computed and observed results, we have confirmed the fundamental validity of the present method. Less