Journal of Tropical Oceanography ›› 2023, Vol. 42 ›› Issue (1): 10-21.doi: 10.11978/2022014CSTR: 32234.14.2022014

Special Issue: 全球变化专题

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Interannual variability of subsurface high salinity water in eastern equatorial Indian Ocean*

TANG Jiaoyu1,2(), WANG Weiqiang1,3,4(), XU Kang1,3, ZHANG Zhenqiu1   

  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
    3. Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China
    4. Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 511458, China
  • Received:2022-01-25 Revised:2022-07-05 Online:2023-01-10 Published:2022-07-21
  • Contact: WANG Weiqiang. email: weiqiang.wang@scsio.ac.cn
  • Supported by:
    National Natural Science Foundation of China(42076020); Strategic Priority Research Program of Chinese Academy of Sciences(XDA20060502); Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou)(GML2019ZD0306); Youth Innovation Promotion Association of Chinese Academy of Sciences(2020340); Rising Star Foundation of South China Sea Institute of Oceanology, Chinese Academy of Sciences(NHXX2018WL0201); Independent Research Project of State Key Laboratory of Tropical Oceanography (South China Sea Institute of Oceanology, Chinese Academy of Sciences)(LTOZZ2101)

Abstract:

Based on the data of the comprehensive scientific cruise survey in eastern Indian Ocean from 2010 to 2019, Argo (array for real-time geostrophic oceanography) and SODA (simple ocean data assimilation), the interannual variability of subsurface high salinity water (SHSW) in eastern equatorial Indian Ocean was studied and its formation mechanisms was explored. The observation results limited to spring show that the high salinity water from Arabian Sea is distributed in 70~130m in eastern Indian Ocean equatorial section and exhibits significant interannual variations. And the result based on monthly SODA reveals that the trend of anomalous salinity of SHSW varies significantly in different periods, with a relatively stable trend from 2010 to 2015 and an obvious increasing trend from 2016 to 2019. Wind field and subsurface zonal current are dominant factors that control the interannual variability of the high salinity water by regression analysis of SHSW. Further analysis indicates that the anomalous easterly wind in equatorial Indian Ocean leads to the westward accumulation of water masses, then generates an eastward pressure gradient force, which in turn stimulates the anomalous subsurface eastward flow, and causes the increases of anomalous salinity of SHSW eventually. The dynamical connection is particularly remarkable in Indian Ocean Dipole, which further indicates that the interannual variability of SHSW is modulated by Indian Ocean Dipole.

Key words: eastern equatorial Indian Ocean, Arabian Sea high salinity water, subsurface high salinity water, Indian Ocean dipole