Journal of Marine Sciences ›› 2021, Vol. 39 ›› Issue (3): 1-11.DOI: 10.3969/j.issn.1001-909X.2021.03.001

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The characteristics and formation mechanism of the oceanic mesoscale eddy origin in northwest of Sumatra

ZHANG Jiaying1,2, ZHOU Feng*1,2,3, TIAN Di1,2, HUANG Ting1,2,3   

  1. 1.State Key Laboratory of Satellite Ocean Environment Dynamics, Hangzhou 310012, China; 
    2.Second Institute of Oceanography, Ministry of NaturalResources, Hangzhou 310012, China; 
    3.School of Oceanography, Shanghai Jiao Tong University, Shanghai 200030, China
  • Online:2021-09-15 Published:2021-09-15

Abstract: There are abundant mesoscale phenomena in the Bay of Bengal and near the mouth of the bay. In this study, a 2.0 version of the Chelton's data set was used, which can distinguish mesoscale eddies in low-latitude regions, and obtain the genesis distribution of mesoscale eddies by tracing. The northwest sea off Sumatra (the area with 5 °N,94 °E as the core) is an important origin of mesoscale eddies. The eddy tracking of Lagrangian method shows that there were 57 cyclonic and 40 anticyclonic mesoscale eddies in the origin (3°N—6°N, 92°E—95°E) during 19932017. Spectrum analysis indicates that there are two significant periods of 180-day and 360-day in sea surface height anomalies. The dynamic mechanism of mesoscale eddies in this origin is the combined effect of topography and wind field, the Rossby wave propagating westward along 5°N increases instability and triggers the mesoscale eddy generation under the action of the ridge topography. The equatorial wind field is an important source of energy in the origin, and the local wind field can induce the polarity of the mesoscale eddy. This study also reveals the reason why the previous literatures described the northwest sea area off Sumatra as a high eddy kinetic area, but failed to identify many mesoscale eddies.

Key words: mesoscale eddy, eddy origin, eddy identification, statistical characteristic analysis, Rossby wave, Bay of Bengal

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