数据驱动印度洋海域全局动力学研究

海洋洋流运动非常复杂, 研究其内在规律能为海上搜救、污染物扩散预测和海运航线设计提供科学依据. 本文将基于空间离散思路的广义胞映射方法应用于数据驱动的海洋系统全局动力学分析中, 研究印度洋海域的长期和短期内在动态结构及其特性. 文中考虑到印度洋海域典型季风气候等因素的影响, 利用1979—2019年该区域浮漂历史数据, 建立不同时间尺度(天、季节或年度)下表征系统状态演化的一步转移概率矩阵, 并以此形成以胞刻画的海洋系统数据驱动动力学模型. 通过拓扑分析, 实现对印度洋海域洋流长短期动态全局吸引性结构(涡漩中心)及其影响区域(涡旋区)的表征. 对比分析显示, 浮漂样本的实际观察与预测的响应分布和演化特征高度吻合, 从而验证所提方法和结果的有效性和正确性. 研究结果表明: 大约在南纬20° ~ 40°, 东经40° ~ 96°范围内可形成明显的长期大范围的稳定涡旋区域, 导致大部分表面漂浮物动态聚集在该区域, 而南纬40°以南和赤道附近则表现为海洋表面流动的排斥性. 同时, 海洋系统中的短期动态涡旋结构主导了表面漂浮物的瞬态路径和趋势, 在2014年3月8日—14日期间形成南印度洋洋流的逆时针环流特点. 

DATA-DRIVEN GLOBAL DYNAMICS OF THE INDIAN OCEAN

The inherent law and mechanism, underlying the complex ocean currents in sea, can offer scientific support for marine engineering, such as search and rescue at sea, pollutant diffusion forecast, shipping route design. In this paper, the generalized cell mapping method based on the idea of space discretization is proposed to carry out the global analysis for finding long-term and short-term dynamic structures underlying the Indian Ocean. Taking the typical monsoon and climate features in the ocean region into account, the one step transition probability matrices in different interval levels are created based on the drifter database from 1979—2019 to describe the evolutions of state of the system. Then, the long-term and short-term profiles of attraction (vortex core) and its region of influence (vortex area) are revealed and characterized by means of topological analysis. In comparison, the predicted distributions and features of responses are highly consistent with real observations of drifters to verify the rationality and validity of the proposed method and results. It is shown that the long-term vortex area is obviously presented in the region of latitude 20° to 45° south, longitude 40° to 96° east, which causes the dynamic concentration of drifters on the region, while the repellency for drifter trajectories is also observed both near the south of latitude 40° south and the equator. Meanwhile, the short-term dynamic vortices can dominate transient paths and tendency of drifters to induce the counterclockwise circulation of current in the southern Indian Ocean.