THE FEATURES OF SOUTH CHINA SEA SUMMER MONSOON ONSET OF 2004 AND THE POSSIBLE EFFECTS OF LAND SURFACE PROCESS IN INDO CHINA PENINSULA II： NUMERICAL SIMULATION

Based on the diagnostic studies in part I, this second companion paper addresses the issue of possible effects of land-surface process over Indo-China Peninsula on the establishment of 2004 South China Sea (SCS) summer monsoon by using the MM5/NOAH LSM modeling systems. A series of numerical simulations were performed in order to investigate the sensitivity of SCS summer monsoon onset to regional soil moisture and precipitation anomalies. It is found that though the SCS summer monsoon onset date is essentially unaltered, soil moisture and precipitation anomalies over Indochina peninsula can make contributions to the intensity variations of SCS summer monsoon. Dry anomalies induced by the decrease of initial soil moisture and precipitation are associated with sensible heat flux increase and positive surface air temperature anomalies, which may led to the decrease of low-level air temperature difference (negative difference) between Indo-China Peninsula and SCS, and then weaken the SCS summer monsoon. In contrast, wet anomalies may intensify the SCS summer monsoon. These results revel that prior to the SCS summer monsoon onset, convection, and precipitation variations over the Indo-China Peninsula and the associated soil moisture anomalies to some extent affect the SCS summer monsoon establishment process. The article also discuss the associated low-level atmospheric condition and land surface energy and hydrology budgets over different land surface properties, analyze the corresponding physical mechanisms of how land surface process affect the SCS summer monsoon.