【摘要】：Rammasun intensified rapidly from tropical storm to super typhoon in the northern South China Sea(NSCS)before its landfall on Hainan Island. Analysis of observed data shows that the anomalous ocean upper layer warm water(WW) is important to the rapid intensification of Rammasun. During the period of Rammasun, sea surface temperature(SST) in the NSCS was much warmer than the climatological SST. The anomalous WW supplied more energy to Rammasun, resulting in its rapid intensification. Numerical simulations further confirm that the NSCS WW plays an important role in the rapid intensification of Rammasun. As the WW is removed, the intensification of Rammasun is only 25 h Pa, which is 58.1% of that in the original SST-forced run.