Major driver leading to winter SST variability in the Kuroshio recirculation gyre region and its decadal changes: Refreshening versus spring‐initiated reemergence processes
Résumé
The analyses using reanalysis data and one-dimensional ocean model during the past decades (1963-2012) revealed that the epoch-dependent refreshening and reemergence mechanisms alternatively influenced the winter sea surface temperature (SST) in the Kuroshio recirculation gyre region. During 1971-1985, the refreshening mechanism due to the strong East Asian winter monsoon significantly contributed to the interannual winter SST variability, consistent with previous works. In contrast, the spring-initiated reemergence process better explains the winter SST variability for 1991-2005, a period corresponding to a declined winter monsoon. The classical winter-to-winter reemergence did not occur during either studied period; thus, the observed spring-to-winter reemergence is an original feature in the Kuroshio recirculation gyre region. The winter monsoon-related strong atmospheric forcing and prominent year-to-year variability of spring SST are important prerequisites for the regional refreshening and reemergence of the winter SST anomaly, respectively.
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