Scientific Reports (Jul 2021)

Mooring observed intraseasonal oscillations in the central South China Sea during summer monsoon season

  • Sen Jan,
  • Ming-Huei Chang,
  • Yiing Jang Yang,
  • Chung-Hsiung Sui,
  • Yu-Hsin Cheng,
  • Yu-Yu Yeh,
  • Chung-Wei Lee

DOI
https://doi.org/10.1038/s41598-021-93219-3
Journal volume & issue
Vol. 11, no. 1
pp. 1 – 12

Abstract

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Abstract The South China Sea (SCS) is a high biodiversity region in the world ocean, supports abundant marine resources to the peripheral nations, and affects weather/climate in southeast Asia. A better understanding of its circulation is important to better prediction and management of the SCS. Here we reveal sizable intraseasonal oscillations at period ~ 50 days between May and November 2017 in the acoustic Doppler current profiler observed velocity in the central SCS. Satellite observed wind and sea level data together with a process-oriented numerical experiment suggest that the oscillations were caused by locally-generated and remotely-penetrated westward-propagating Rossby waves. The summer southwesterly monsoon strengthening/weakening and the resultant Ekman pumping velocity and shoreward Ekman transport increase/decrease and consequent coastal sea level rise/fall off the west coast of Palawan create westward-propagating Rossby waves causing velocity oscillations in the central SCS. Besides the local generation, Rossby waves with sea level anomaly > 0.2 m propagating from the Pacific through the Sulu Sea into the SCS could contribute to the intraseasonal velocity oscillations in the central SCS.