Research On The Onset Of South China Sea Monsoon And The Reconstructure Of South Asia High

In term of NCEP / NCAR reanalysis data, the characteristics of the onset of South China Sea (SCS) summer monsoon and the westward of South Asia High (SAH) are analyzed. The onset of SCS summer Monsoon is simulated by means of numerical model. The main results are as follows:(1) It is found that the SCS summer monsoon establishment is characterized by the SAH migrating swiftly to Indo-China Peninsula (ICP) and the Bay of Bengal (BOB) trough deepening, the subtropical high belt break and withdraws associated with the westerly expanding to the South China Sea. The meridian temperature difference (MTD) experience abrupt change before the onset of SCS summer monsoon, While the area between 100 ~ 110°E belongs to the intermediate belt and the area where the sign of MTD switch vary the earliest.(2) By analyzing multi year mean data, it is revealed that during the SAH migrating westward in Mar., there is a splitting and reconstruction process. The SAH is not just moving west but split above Philippines, then the west part enhances and the eastern disappear. It can be verify by analyzing mutil year data, what's more, the recon structure period can be used as the index of SCSM.(3)Associated with the reconstruction of SAH, the tropical convection expands north from Sumatra along ICP. The latent heat release might lead to the reconstruction of the SAH.(4) The numerical experiment shows that GRAPES successfully reproduces the evolution of summer monsoon's onset, such as the rapid conversion of easterlies and the subtropical high withdrawing. With the NOAA17 AMSUB data assimilated into the initial field, the simulation has distinguished improvement. The disturb from mid- latitude and the westly of India Ocean have affect on the onset of SCSM.(5) Simulations of the reconstructive process of SAH have be done to reveal the relations between the SAH and the latent heat on Indo-China Peninsula.