Evaluations for flow fields in a coastal reion with satellite-image analysis and numerical simulation

黑潮、大潮等洋流对日本-中国周边流场影响较大，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极轨气象卫星的图像处理技术，对海面水温和速度矢量的大尺度格局进行了监测，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，我们试图开发一种精确的工具，通过卫星图像处理和数值模拟来评估沿海流。项目主要成果如下：(1)利用卫星图像分析进行海洋湍流测量利用NOAA/VHRR热红外数据进行了湍流可视化和海面速度测量。我们每天都在办公室直接采集卫星数据，不间断地进行海洋湍流监测。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边海洋湍流数据库。(2)采用改进的数值模式模拟沿海流，为了有效地考虑近海对沿海流模拟的影响，提出了一种新的沿海流模式单向嵌套程序，并将其应用于孤岛周边沿海流模拟。在此基础上，提出了双向交互嵌套过程，对上述嵌套模型进行了改进。我们还尝试提高三维数值模型的数值精度，特别注意流体静力近似和西格玛坐标Less

Ocean currents such as the Kuroshio and Oyashio, which strongly influence on the flow fields around Japan-Island-China, 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 monitored 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, we here tried to develop an accurate tool to evaluate coastal currents with the satellite-image processing and numerical simulations. The main results of the project … More 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/VHRR thermal infrared data. Every day the monitoring of the oceanic turbulence has been continuously performed by directly capturing the satellite data in our office. 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) Coastal current simulations with improved numerical modelsTo effectively incorporate offshore influences on coastal current simulations, a new one-waynesting procedure for coastal current model was developed and then applied to the coastal current simulation around an isolated island. Furthermore, we presented the two-way interactive nesting procedure to modify the above nesting model. We also attempted to improve the numerical accuracy of the 3D numerical models with special attentions to the hydrostatic approximation and sigma-coordinates Less