热带海洋学报 ›› 2026, Vol. 45 ›› Issue (1): 140-153.doi: 10.11978/2025024CSTR: 32234.14.2025024

• 海洋水文学 • 上一篇    下一篇

印度洋赤道深层流的季节内变化特征及其驱动机制*

钟卿文1,2(), 陈更新1(), 陈举1, 何云开1   

  1. 1热带海洋环境与岛礁生态全国重点实验室(中国科学院南海海洋研究所), 广东 广州 511458
    2中国科学院大学, 北京 100049
  • 收稿日期:2025-02-18 修回日期:2025-03-25 出版日期:2026-01-10 发布日期:2026-01-30
  • 通讯作者: 陈更新, 研究员, 博士生导师。email: chengengxin@scsio.ac.cn
  • 作者简介:

    钟卿文(1997—), 广东省韶关市人, 博士研究生, 研究方向为海洋环流与波动动力学。email:

    *本研究所使用的数据来自国家自然科学基金共享航次计划项目, 相关航次编号(及项目批准号)为: NORC2015-10(41549910)、NORC2016-10(41649910)、1ORC2017-10(41749910)、NORC2018-10(41849910)、NORC2019-10(41949910)、NORC2020-10(42049910)、NORC2022-10+NORC2022-303(42149910), 航次由“实验1号”“实验3号”和“实验6号”组织实施, 在此一并致谢

  • 基金资助:
    国家自然科学基金共享航次计划项目(42149910); 国家自然科学基金(42476199); 国家自然科学基金(42476022); 国家自然科学基金共享航次计划项目(41549910); 国家自然科学基金共享航次计划项目(41649910); 国家自然科学基金共享航次计划项目(41749910); 国家自然科学基金共享航次计划项目(41849910); 国家自然科学基金共享航次计划项目(41949910); 国家自然科学基金共享航次计划项目(42049910)

Intraseasonal variability and dynamical mechanisms of equatorial deep currents in the Indian Ocean*

ZHONG Qingwen1,2(), CHEN Gengxin1(), CHEN Ju1, HE Yunkai1   

  1. 1State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 511458, China
    2University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2025-02-18 Revised:2025-03-25 Online:2026-01-10 Published:2026-01-30
  • Contact: CHEN Gengxin. email: chengengxin@scsio.ac.cn
  • Supported by:
    Shiptime Sharing Project of National Natural Science Foundation of China (NSFC)(42149910); National Natural Science Foundation of China(42476199); National Natural Science Foundation of China(42476022); Shiptime Sharing Project of National Natural Science Foundation of China (NSFC)(41549910); Shiptime Sharing Project of National Natural Science Foundation of China (NSFC)(41649910); Shiptime Sharing Project of National Natural Science Foundation of China (NSFC)(41749910); Shiptime Sharing Project of National Natural Science Foundation of China (NSFC)(41849910); Shiptime Sharing Project of National Natural Science Foundation of China (NSFC)(41949910); Shiptime Sharing Project of National Natural Science Foundation of China (NSFC)(42049910)

摘要:

本文利用2015年3月—2021年5月热带印度洋观测网(tropical Indian Ocean observation net, TIOON)在赤道80°E、85°E和93°E布设的观测潜标所获取的环流时间序列, 结合BRAN2020 (Bluelink ReANalysis)环流流速数据以及JRA-55(Japanese 55-year Reanalysis)气象数据, 研究了印度洋赤道深层环流(1200m以下)的季节内变化特征及其驱动机制。观测结果显示, 深层环流流速平均值接近0, 纬向流速标准偏差范围为2.5~3.1cm·s−1, 经向流速标准偏差范围为2.6~3.1cm·s−1。纬向流和经向流的季节内周期信号强度分别占各自总流动强度的88%~91%和74%~84%, 揭示了深层环流中的显著季节内周期变率特征。小波分析表明, 深层纬向流季节内信号主要周期为10~100d, 其中80°E处的周期较长(50~90d), 而93°E处的主要为50d及更高频信号, 表现为蓝移现象, 即环流变化的主导频率随位置靠东而变高的现象。经向流季节内信号以60d周期最显著。赤道风应力异常是深层环流季节内变率的重要驱动因素。中海盆(80°E和85°E)深层环流季节内变率主要受纬向风应力异常驱动, 通过反射波动过程调制; 基于低阶斜压模态, 能量通过Kelvin波在东边界反射后形成的Rossby波向深层传递。东海盆(93°E)深层环流季节内变率主要受纬向和经向风应力异常驱动, 通过直接波动过程调制; 基于多阶斜压模态, 能量通过在环流西侧由风直接驱动产生的Yanai波向深层传递。根据线性波动理论, 本研究刻画了上述赤道波的能量传播射线, 结果显示地形对赤道波调制深海环流的动力过程有重要影响: 中海盆的平坦地形有利于向下向西传播能量的反射波动过程, 而90°E海脊可能会阻碍向下向东传播能量的直接波动过程。在平坦地形区域, 正压不稳定过程在经向上无显著差异且强度弱, 区域平均结果显示能量主要由平均流向环流季节内变率释放; 90°E海脊附近, 环流季节内变率与平均流之间存在更强的非线性动力作用, 表现为环流季节内变率向平均流转移能量。本研究加深了对深层环流动力学的理解, 为改进深海环流模拟提供了观测依据。

关键词: 印度洋环流, 赤道深层流, 季节内变率, 赤道波动

Abstract:

This paper examines the intraseasonal variability of equatorial deep currents (below 1200 m) in the Indian Ocean, utilizing time series data spanning from 2015 to 2021. These data were obtained from TIOON (tropical Indian Ocean observation net) moorings positioned at 80°E, 85°E, and 93°E on the equator, supplemented by continuous current velocity data from BRAN2022, wind velocity data from JRA-55, and temperature-salinity data from WOA23. Observations reveal that the standard deviation (STD) of zonal current velocities at these locations ranges from 2.5 to 3.1 cm·s−1, while the STD of meridional current velocities ranges from 2.6 to 3.1 cm·s−1. Notably, intraseasonal variability accounts for 88%-91% and 74%-84% of the total current variability for the zonal and meridional currents, respectively, underscoring its significance. Wavelet analysis indicates that the primary period of intraseasonal deep zonal currents is 10-100 days, with a longer period (50-90 days) observed at 80°E and a shorter period (< 50 days) at 93°E. This suggests a blue-shift phenomenon, where the variability in deep currents shifts to higher frequencies toward the east. Additionally, intraseasonal meridional currents exhibit a significant peak at the 60-day period. Equatorial wind stress anomalies are a crucial forcing factor driving intraseasonal variability in deep currents through both direct and reflected wave processes. In the central basin (80°E and 85°E), intraseasonal variability is primarily driven by zonal wind stress anomalies and modulated by a reflected wave process. Energy is transferred to the deep layers via Rossby waves formed by Kelvin waves reflected at the eastern boundary, primarily involving low-order baroclinic modes. Conversely, in the eastern basin (93°E), intraseasonal variability is driven by both zonal and meridional wind stress anomalies and modulated by a direct wave process. Energy is transferred to the deep layers via Yanai waves generated directly west of the current, involving multi-order baroclinic modes. Based on linear wave theory, this study illustrates the energy propagation rays of equatorial beams, emphasizing the critical role of topography in deep circulation dynamics. The flat topography of the central basin facilitates downward and westward energy propagation through reflected wave processes, while the ridge near 90°E may impede downward and eastward energy propagation through direct wave processes. Barotropic conversion (T4) analysis reveals strong nonlinear dynamics near the 90°E ridge, with significant energy transfer from intraseasonal variability to the mean flow. In contrast, over flat topography, the energy transfer is reversed—from the mean flow to intraseasonal variability—though notably weak. This study enhances our understanding of deep current dynamics and provides observational evidence to improve deep ocean circulation simulations.

Key words: Indian Ocean circulation, equatorial deep current, intraseasonal variability, equatorial wave

中图分类号: 

  • P731.27