中文摘要：

利用OAFlux热通量资料和ERA-Interim高度场资料，分析了热带印度洋区域潜热通量的变化与南海夏季风爆发之间的关系，初步探讨了热带印度洋潜热通量变化对南海夏季风爆发早晚的影响过程。结果表明，2月热带印度洋区域的潜热通量与南海夏季风爆发之间存在密切的联系，当2月热带印度洋区域潜热通量较常年偏多（少）时，当年南海夏季风爆发偏晚（早）。当2月热带印度洋的潜热通量异常偏多（少）时，海洋向大气释放更多（少）的潜热，潜热通量通过对流凝结作用对大气加热形成大气热源，再通过大气环流逐渐影响2—4月的高度场，使得南海上空的850hPa高度场出现异常偏高（低），即副热带高压偏强（弱）。异常强（弱）的副热带高压结合孟加拉湾弱（强）的异常西南风，造成南海夏季风爆发偏晚（早）。因此可以认为热带印度洋2月的潜热通量变化是影响南海夏季风爆发的重要因素。

英文摘要：

In order to study the influencing factors for the onset of South China Sea summer monsoon （SCSSM）, this paper uses the OAFlux heat flux data and ERA-Interim geopotential height data to analyze the relationship between the variability of latent heat flux over tropical Indian Ocean and the onset of SCSSM. It then studies the process of influence of the latent heat flux over tropical Indian Ocean on the onset of SCSM. The results show that there is close correlation between the onset of SCSSM and the latent heat flux over the tropical Indian Ocean in February. The onset of SCSSM is later （earlier） when the latent heat flux is larger （smaller） over the tropical Indian Ocean in February. Further study shows that the larger （smaller） latent heat flux over tropical India Ocean in February heats the air to form a local atmospheric heat source. Then the-heat source influences the geopotential height field from February to April via the atmospheric circulation . These make the subtropical high stronger （weaker） at 850 hPa in April. The abnormal strong （weak） subtropical high and the weaker （stronger） southwest wind will directly affect the onset of SCSSM later （earlier）. It is suggested that the latent heat flux over the tropical Indian Ocean in February is the primary mechanism that influences the onset of SCSSM.