Journal of Tropical Oceanography ›› 2023, Vol. 42 ›› Issue (1): 1-9.doi: 10.11978/2022038CSTR: 32234.14.2022038

Special Issue: 全球变化专题

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Low-frequency wind stress forcing reduces El Niño diversity in numerical model

ZHANG Qi1(), LIAN Tao1,2,3()   

  1. 1. State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310000, China
    2. School of Oceanography, Shanghai Jiao Tong University, Shanghai 200000, China
    3. Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519000, China
  • Received:2022-02-24 Revised:2022-04-08 Online:2023-01-10 Published:2022-04-21
  • Contact: LIAN Tao. email: liantao@sio.org.cn
  • About author:
    ZHANG Qi (1997—), male, master student. email:
  • Supported by:
    National Natural Science Foundation of China(42022043); Zhejiang Provincial Natural Science Foundation of China(LR19D060001)

Abstract:

The El Niño-Southern Oscillation (ENSO) includes both low-frequency ocean-atmosphere coupling and high-frequency processes, yet the nonlinearity in ENSO dynamics prevents any quantitative estimation of the contributions of the two to ENSO development. The online low-frequency filtering technique was proposed in a recent work to exclude the high-frequency part of wind stress during ocean-atmosphere coupling in model, thus can be used to scale the impact of low-frequency ocean-atmosphere interaction on the ENSO dynamics. By comparing model simulations with and without the online low-pass filtering module, we found that removing the high-frequency wind forcing prolongs ENSO period and decreases El Niño diversity. The results confirm that the high-frequency momentum processes play a crucial role in the genesis of El Niño diversity.

Key words: coupling model, online low-frequency filtering, ENSO