Examination of seasonal variation of the equatorial undercurrent termination in the Eastern Pacific diagnosed by ECCO2

Jie WANG; Xuezhi BAI; Hengling LENG

doi:10.1007/s00343-021-0308-6

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Examination of seasonal variation of the equatorial undercurrent termination in the Eastern Pacific diagnosed by ECCO2

Physics | Updated：2023-05-20

- Examination of seasonal variation of the equatorial undercurrent termination in the Eastern Pacific diagnosed by ECCO2
- Examination of seasonal variation of the equatorial undercurrent termination in the Eastern Pacific diagnosed by ECCO2
- 海洋湖沼学报（英文） 2022年40卷第3期页码：870-890
- Affiliations：
  
  1.College of Oceanography, Hohai University, Nanjing 210098, China
  2.Key Laboratory of Marine Hazards Forecasting, Ministry of Natural Resources, Hohai University, Nanjing 210098, China
- Author bio：
  
  Xuezhi BAI, xuezhi.bai@hhu.edu.cn
- Funds：
  
  the National Key Research and Development Program of China(2017YFA0604600);the Fundamental Research Funds for the Central Universities(2019B63014);National Natural Science Foundation of China(41676019);© Chinese Society for Oceanology and Limnology, Science Press and Springer-Verlag GmbH Germany, part of Springer Nature 2022
- DOI：10.1007/s00343-021-0308-6
  中图分类号：
- 纸质出版：2022-03
- Accepted：
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Examination of seasonal variation of the equatorial undercurrent termination in the Eastern Pacific diagnosed by ECCO2[J]. 海洋湖沼学报（英文）, 2022,40(3):870-890.

Jie WANG, Xuezhi BAI, Hengling LENG. Examination of seasonal variation of the equatorial undercurrent termination in the Eastern Pacific diagnosed by ECCO2[J]. Journal of Oceanology and Limnology, 2022, 40(3): 870-890.
Examination of seasonal variation of the equatorial undercurrent termination in the Eastern Pacific diagnosed by ECCO2[J]. 海洋湖沼学报（英文）, 2022,40(3):870-890. DOI： 10.1007/s00343-021-0308-6.

Jie WANG, Xuezhi BAI, Hengling LENG. Examination of seasonal variation of the equatorial undercurrent termination in the Eastern Pacific diagnosed by ECCO2[J]. Journal of Oceanology and Limnology, 2022, 40(3): 870-890. DOI： 10.1007/s00343-021-0308-6.

摘要

Abstract

Seasonal variations of the equatorial undercurrent (EUC) termination in the Eastern Pacific

and their mechanism were examined using the Estimating the Circulation and Climate of the Ocean

Phase Ⅱ (ECCO2). The ECCO2 reproduced a weak and shallow eastward EUC east of the Galapagos Islands

with annual mean transport of half of EUC to the west of the Islands. The diagnosis of zonal momentum equation suggests that the zonal advection (nonlinear terms) drives the EUC beyond the Islands rather than the pressure gradient force. The EUC in the Far Eastern Pacific has the largest core velocity in boreal spring and the smallest one in boreal summer

and its volume transport exhibits two maxima in boreal spring and autumn. The seasonal variability of the EUC in the Eastern Pacific is dominated by the Kelvin and Rossby waves excited by the zonal winds anomalies in the central and Eastern Pacific that are associated with the seasonal relaxation or intensification of the trade wind. In the Far Eastern Pacific to the east of 120°W

the eastward propagation Kelvin waves play a dominate role in the seasonal cycle of the EUC

results in a semiannual fluctuation with double peaks in boreal spring and autumn. A construction of water mass budget suggests that approximately 24.1% of the EUC water east of 100°W has upwelled to the mixed layer by 0.35 m/d. The estimated upwelling is strongest during boreal autumn and weakest during boreal winter. It is also found that approximately 42.6% of the EUC turns westward to feed the south equatorial current (SEC)

13.2% flows north of the equator

and 20.1% flows south of the equator

mainly contributing to Peru-Chile undercurrent.

关键词

Keywords

references

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