The tide level displays information about the state of the sea current and the tidal motion. The tide level of the southern coast of Japan Island is affected strongly by Kuroshio Current flowing in the western part of...The tide level displays information about the state of the sea current and the tidal motion. The tide level of the southern coast of Japan Island is affected strongly by Kuroshio Current flowing in the western part of North Pacific Ocean. When Kuroshio takes the straight path and flow along the Japan Islands, the tide level increases, and it is calculated from two tide level data observed at Kushimoto and Uragami in the southern part of Kii Peninsula. In contrast, the tide level decreases at the time when Kuroshio leaves from the Japan Islands. In this paper, the hourly tidal data are analyzed using the Autocorrelation Function (ACF) and the Mutual Information (MI) and the phase trajectories at first. We classify the results into 5 types of tidal motion. Each categorized type is investigated and characterized precisely using the mean tide level and the unit root test (ADF test) next. The frequency of the type having unstable tidal motion increases when the Kuroshio Current is non-meandering or in a transition state or the tide level is high, and the type shows a non-stationary process. On the other hand, when the Kuroshio Current meanders, the tidal motion tends to take a periodical and stable state and the motion is a stationary process. Though it is not frequent, we also discover a type of stationary and irregular tidal motion.展开更多
文摘利用7套温盐初始场、5套开边界强迫场海洋数据产品与温盐流观测数据,基于有限体积海岸模型(Finite-Volume Coastal Ocean Model,FVCOM),开展数值模型的初始场敏感性试验与开边界敏感性试验,定义一个分叉角度指标描述黄海暖流分叉特征,利用小波分析和功率谱分析方法研究分叉角度的冬季季节内变率,进而分析冬季东中国海的流场结构,包括黑潮、台湾暖流、对马暖流等的路径、来源特征。结果表明:在渤、黄、东海中,使用涡解高精度海洋模型(OGCM for the Earth Simulator,OFES)的再分析数据作为温盐初始场,以及使用简单海洋数据同化资料(Simple Ocean Data Assimilation,SODA)作为开边界强迫场时,温盐流与观测值综合偏差最小,FVCOM的冬季数值结果最可靠;使用分叉角度指标可以直观地描述冬季黄海暖流的消退变化,受风场影响,分叉角度存在3 d、5~8 d的强周期变化。
文摘The tide level displays information about the state of the sea current and the tidal motion. The tide level of the southern coast of Japan Island is affected strongly by Kuroshio Current flowing in the western part of North Pacific Ocean. When Kuroshio takes the straight path and flow along the Japan Islands, the tide level increases, and it is calculated from two tide level data observed at Kushimoto and Uragami in the southern part of Kii Peninsula. In contrast, the tide level decreases at the time when Kuroshio leaves from the Japan Islands. In this paper, the hourly tidal data are analyzed using the Autocorrelation Function (ACF) and the Mutual Information (MI) and the phase trajectories at first. We classify the results into 5 types of tidal motion. Each categorized type is investigated and characterized precisely using the mean tide level and the unit root test (ADF test) next. The frequency of the type having unstable tidal motion increases when the Kuroshio Current is non-meandering or in a transition state or the tide level is high, and the type shows a non-stationary process. On the other hand, when the Kuroshio Current meanders, the tidal motion tends to take a periodical and stable state and the motion is a stationary process. Though it is not frequent, we also discover a type of stationary and irregular tidal motion.
