South China Sea Summer Monsoon Characteristics Analysis And Simulation And Analysis, The South Asia High Westward Characteristics

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 for two years. The main results are as follows:(1) It is found that the SCS summer monsoon establishment is characterized by the SAH migrating swiftly from the eastern side of Philippines 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 to meet the precipitation and convergence from middle-latitude.(2) During the the SAH migrating westward, there is a splitting and reconstruction process. The SAH splat above Philippines, then the west part enhanced and the eastern disappear.(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 meridional temperature difference (MTD) experience abrupt change before the onset of SCS summer monsoon. The sign of MDT changes earlier in low levels and area west of 105° E than other area. While the area between 100 ~ 110°E belongs to the intermediate belt, where the time difference of the sign of MTD switch vary relatively small.( 5 ) Analyzed the onset of SCS summer monsoon and simulated with numerical model. 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.