链接热带东印度洋环流的海洋波动桥梁

The Ocean Wave Bridge Linking the Circulation in the Tropical Eastern Indian Ocean

热带印度洋环流动力研究对认识海盆尺度物质和水体交换、区域乃至全球气候变化具有重要意义,亦服务于人类的生产生活。回顾了近年来基于中国科学院南海海洋研究所热带印度洋观测取得的环流动力方面的研究进展,探讨提出海洋波动桥梁概念,即:赤道波通过水平传播、垂向传播和东边界反射,在赤道上混合层、次表层和中深层调制着赤道流系的生成与变化;随着波动能量在东边界以沿岸开尔文波和反射罗斯贝波的形式往外赤道传输,赤道动力过程亦调节着外赤道的环流结构变化。作为能量传输的十字路口,海洋东边界是环流变化的动力支点。在其支撑下,海洋波动成为环流间重要的能量纽带,贡献于环流的动力联系,是东印度洋环流多尺度变化的重要内因。基于观测,初步探讨了大尺度气候模态等外因对热带东印度洋环流的影响。凝练的海洋波动桥梁动力学框架,为进一步研究热带印度洋的环流的特征、变化及影响提供科学启示。

A large-scale hydrological observational network has been maintained in the tropical Indian Ocean since 2010 by the South China Sea Institute of Oceanography,Chinese Academy of Sciences(CAS).This paper reviews the research progress on the circulation dynamics over recent years based on the CAS observations. The results reveal an "ocean wave bridge in the eastern boundary". On the equator,the currents in the upper layer,the thermocline,and the middle layer are significantly modulated by the equatorial Kelvin and Rossby waves directly forced by equatorial winds and reflected from the eastern boundary,which effectively transport energy horizontally and vertically. Off the equator,the currents are still regulated by the equatorial dynamics,as equatorial-origin wave signals transmit energy there relying on the eastern boundary in the form of coastal Kelvin waves and reflected Rossby waves. Under the support of the dynamic fulcrum of the eastern boundary,the ocean wave bridge is thus an energy belt,which links generation and variation of the circulation in the tropical eastern Indian Ocean. In addition to the internal factor,contributions of external factors such as large-scale climate mode on the circulation are also discussed. The dynamic framework of ocean wave bridge will provide scientific enlightenment for further research on the characteristics,changes,and effects of the tropical Indian Ocean circulation.