Title: Selective Response of the South China Sea Circulation to Summer Monsoon

Journal: Journal of Physical Oceanography, 47:1555-1568, doi:10.1175/JPO-D-16-0288.1

Authors: YANG H. -Y.*, L. -X. Wu, S. -T. Sun, and Z. -H. Chen

Abstract: The response of the South China Sea (SCS) circulation to intraseasonal variability of the summer monsoon is studied with both observations and a 1.5-layer reduced-gravity model. Intraseasonal variability of the SCS summer monsoon is characterized by evolution of the wind jet intensity in the midbasin with typical amplitude of 6 m s−1 and several peaks on its power spectrum between 10 and 60 days. However, this study finds that intraseasonal variability of the sea surface height (SSH) in the SCS presents significant variability to the southeast of Vietnam with amplitude of 6 cm and a period only between 40 and 60 days. This implicates the frequency selectivity of oceanic response to wind forcing. Numerical experiments suggest that the intrinsic variability of the SCS circulation accounts for this phenomenon. Based on the Rossby basin mode theory, this is explained by the interaction between the long, westward-propagating Rossby waves and the short, eastward-propagating Rossby waves.