热带海洋学报 ›› 2025, Vol. 44 ›› Issue (1): 66-81.doi: 10.11978/2024034CSTR: 32234.14.2024034

• 海洋水文学 • 上一篇    下一篇

南海西北部连续台风激发的近惯性内波观测研究

刘杰1,2(), 闫桐1(), 经志友1   

  1. 1.热带海洋环境国家重点实验室, 中国科学院南海海洋研究所, 广东 广州 510301
    2.中国科学院大学, 北京 100049
  • 收稿日期:2024-01-30 修回日期:2024-02-22 出版日期:2025-01-10 发布日期:2025-02-10
  • 通讯作者: 闫桐
  • 作者简介:

    刘杰(1997—), 男, 安徽省阜阳市人, 硕士研究生, 从事海洋内波研究。email:

    两位匿名审稿专家和编辑对稿件提出的修改意见。

  • 基金资助:
    国家重点研发计划项目(2023YFC3008003); 国家重点研发计划项目(2023YFC3008001); 国家自然科学基金项目(42149907); 国家自然科学基金项目(42349907); 国家自然科学基金项目(42349584); 中国科学院南海海洋研究所自主部署项目(SCSIO202201); 中国科学院南海海洋研究所自主部署项目(SCSIO202204); 中国科学院南海海洋研究所自主部署项目(SCSIO202209); 中国科学院南海海洋研究所自主部署项目(SCSIO2023QY02)

Observations of near-inertial waves generated by three successive typhoons in the northwestern South China Sea

LIU Jie1,2(), YAN Tong1(), JING Zhiyou1   

  1. 1. State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2024-01-30 Revised:2024-02-22 Online:2025-01-10 Published:2025-02-10
  • Contact: YAN Tong
  • Supported by:
    National Key Research and Development Program of China(2023YFC3008003); National Key Research and Development Program of China(2023YFC3008001); National Natural Science Foundation of China(42149907); National Natural Science Foundation of China(42349907); National Natural Science Foundation of China(42349584); Development Fund of South China Sea Institute of Oceanology of the Chinese Academy of Sciences(SCSIO202201); Development Fund of South China Sea Institute of Oceanology of the Chinese Academy of Sciences(SCSIO202204); Development Fund of South China Sea Institute of Oceanology of the Chinese Academy of Sciences(SCSIO202209); Development Fund of South China Sea Institute of Oceanology of the Chinese Academy of Sciences(SCSIO2023QY02)

摘要:

文章基于2020年10—11月南海西沙潜标观测资料, 详细研究了三个连续台风激发近惯性内波(near-inertial waves, NIWs)的特征, 分析了不同台风引起NIWs的特征参数、衰减时间尺度、垂向结构, 以及背景涡度和流场对NIWs频率的调制作用。观测期间, 台风Saudel、Molave和Vamco激发NIWs垂向波长分别为109m、133m和117m, 垂向群速度分别为29m·d-1、26m·d-1和18m·d-1, 衰减时间尺度分别为3d、7d和15d。分析表明, 层结效应对垂向群速度变化影响显著, 同时Vamco事件中的长时间衰减尺度应为远场传来的EOF(empirical orthogonal function)第2模态NIWs所致。动力模态分解(dynamical mode decomposition, DMD)和EOF分析整体结果一致, 第1模态贡献均显著占优, 且海洋上层NIWs垂向分布结构相近。 在100m以浅、100~150m和150~350m层内, 近惯性动能(near-inertial kinetic energy, NIKE)分别主要分布于DMD的第1、第3和第2模态中。观测的NIWs频率均表现出蓝移特征, 台风Saudel与Molave事件中的蓝移是背景流场的多普勒频移效应和背景涡度的共同作用, Vamco期间气旋式涡旋带来的显著正背景涡度则是蓝移的主要原因。研究结果对深入理解强风致NIWs的结构、传播、衰减与能量分布等特征及其产生机理有裨益, 并且为NIWs在数值模式中的模拟和合理刻画提供了参考。

关键词: 连续台风, 近惯性内波, 模态分解, 南海

Abstract:

Based on mooring data deployed west of the Xisha Islands from October to November 2020, we investigated the characteristics of near-inertial waves (NIWs) triggered by three consecutive typhoons in detail, including the decay time scales and vertical structures of the NIWs, as well as the modulation of the background vorticity and current fields on the NIWs, etc. The vertical wavelengths of NIWs induced by Typhoon Saudel, Molave and Vamco are 109 m, 133 m and 117 m, respectively, and the vertical group speeds are 29 m·d-1, 26 m·d-1 and 18 m·d-1, respectively. The decay time scales for these internal waves are 3 d, 7 d and 15 d, respectively. It reveals that ocean stratification significantly impacts the vertical group speed of NIWs. The longest decay time in the Vamco case is attributed to the second EOF (empirical orthogonal function) mode of NIW propagated from far field. The results of the dynamical mode decomposition (DMD) and EOF are consistent with each other. Both show that the first modes contribute the most to near-inertial kinetic energy (NIKE), and the distributions of NIKE in different modes obtained from DMD and EOF are comparable. For example, the NIKE is mainly distributed in the first, third and second DMD modes at depths of < 100 m, 100~150 m and 150~350 m. The observed frequencies of the NIWs are all blue-shifted, and the blueshifts in Typhoon Saudel and Molave are due to the combination of the background current and vorticity, while the positive background vorticity due to the cyclonic eddy during the Vamco is the main reason for the observed blueshift. Our results are useful for a deeper understanding of the characteristics, propagation, dissipation and energy distribution of strong wind-induced NIWs and their mechanisms, and they also provide a good reference for numerical simulations.

Key words: consecutive typhoons, near-inertial waves, mode decomposition, South China Sea

中图分类号: 

  • P731.24