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Interannual Modulations of the 50‐Day Oscillations in the Celebes Sea: Dynamics and Impact

2018; Wiley; Volume: 123; Issue: 7 Linguagem: Inglês

10.1029/2018jc013960

2169-9291

Xiao Chen, Bo Qiu, Shuiming Chen, Xuhua Cheng, Yiquan Qi,

Tropical and Extratropical Cyclones Research

Abstract Intense 50‐day oscillations have been previously observed at the entrance of Celebes Sea, and their formation has been suggested to be a result of Rossby wave resonance where the frequency of cyclonic eddy shedding by the intruding Mindanao Current matches that of the gravest Rossby mode of the semienclosed Celebes Sea basin. Using the ocean state estimate of 1993–2016 from the Estimating the Circulation and Climate of the Ocean, Phase II, we detected strong interannual modulations in the shedding of cyclonic eddies at the Celebes Sea entrance. Active eddy sheddings occurred during 1993, 2002–2003, 2006–2010, and 2013–2015. Southward shifting of the wind‐driven North Pacific tropical gyre and the concurrent strengthening of the Mindanao Current southeast of the Mindanao Island in these years are found to be inducive for the generation of cyclonic eddies intruding into the Celebes Sea. Modulated by the activity of eddy sheddings, the upper ocean water mass properties in both the Celebes Sea and Makassar Strait exhibit noticeable interannual changes with less saline waters appearing in the 75‐ to 175‐m layer during the active eddy shedding years.