Abstract: The onset of the summer monsoon over the South China Sea is studied by the global spectral model(T42L9) of the Institute of Atmospheric Physics. The onset of the summer monsoon over the South China Sea is closely related to the intense convergence at 850hPa over the South China Sea, which is constituted by the cross-equatorial southerly divergent wind over the eastern Indian, the westerly divergent wind along the southern flank of the Tibetan Plateau, the northerly divergent wind along the eastern periphery of the Plateau, and the easterly divergent wind of the Western Pacific. Various sensitive numerical model experiments show that latent heating of the Southeast Asia and the dynamic effects of the Tibetan Plateau are both very important to those four divergent airstreams and that convergence.

Key words: onset of the South China Sea summer monsoon, numerical model experiment, latent heating of the Southeast Asia, dynamic effect of the Tibetan Plateau