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Optimal Precursors Triggering the Kuroshio Intrusion Into the South China Sea Obtained by the Conditional Nonlinear Optimal Perturbation Approach
Author(s) -
Liang Peng,
Mu Mu,
Wang Qiang,
Yang Lina
Publication year - 2019
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2018jc014545
Subject(s) - altimeter , climatology , perturbation (astronomy) , barotropic fluid , intrusion , anticyclone , geology , nonlinear system , oceanography , geodesy , physics , geochemistry , quantum mechanics
The Kuroshio Intrusion (KI) into the South China Sea (SCS) is a key process that greatly modulates the variability of dominant phenomena in the northern SCS. Using the Regional Ocean Modeling System, the optimal precursor (OPR) triggering the KI is obtained by the Conditional Nonlinear Optimal Perturbation (CNOP) approach. The OPRs exhibit the anticyclonic eddies (AEs) spatial pattern in the southern region (19°N–20.3°N, 119°E–122°E) of the Luzon Strait. The evolution processes of the OPRs indicate that the northwestward movement and rapid growth of AEs force the Kuroshio to bend westward continuously, which leads to the transition of the Kuroshio path from leaping state to intruding state. Eddy‐energetic analyses suggested that the barotropic instabilities are responsible for the evolution of the OPRs and thus triggering the KI, while the local wind stress plays a minor role in the triggering process. Additional examinations based on satellite altimeter data and ocean reanalysis data further confirm that the AE‐like perturbation similar to the obtained OPR indeed plays a key role in the KI triggering process.