中文摘要：

近海台风强度急剧增强是预报中的难点。使用新一代中尺度WRF模式对台风＂海葵＂（1211）近海强度急剧增强过程进行数值模拟,并对数值模拟结果展开分析,研究引起台风强度突变的可能机理及相应结构变化。模拟结果表明,台风＂海葵＂的急剧增强与低层水汽输入的突然增加以及有利的高、低层辐散、辐合流场配置密切相关,且在＂海葵＂台风强度迅速增强的前6 h其高低层辐合、辐散流场呈现同时增强。台风结构变化的分析表明,在台风急剧增强时段台风结构趋于对称化,且低层眼壁范围小,高层眼壁范围向外扩展。伴随着台风强度增强,径向风速和切向风速也处在增大过程中,特别是台风急剧增强阶段,径向风速和切向风速增大更明显。另外,暖心强度逐渐加强,且暖心范围明显扩大并向低层扩展。同时随着台风强度的增强,垂直上升运动也逐渐增强。台风的这些结构变化都有利于其强度的维持和发展。

英文摘要：

The forecast of the rapid intensification of tropical cyclones over the offshore area remains difficult. In this article, the non-hydrostatic WRF （Weather Research and Forecast） model was used to study the rapid intensification of Typhoon Haikui （1211） offshore China. On the basis of successful simulation of the intensity change and track, the model output was further analyzed to determine the mechanism for the rapid intensity change with Typhoon Haikui. The results indicated that a remarkable increase of low-level moisture transportation towards the inner core, a favorable large-scale background field with low-level convergence and high-leve! divergence plays a key role in the rapid intensification of Haikui, and the last factor can be an indicator for the rapid intensity change of Typhoon Haikui about 6 hours in advance. Analyses on the structure change showed that the typhoon was structurally symmetric during the rapid intensification, and the range of eyewall was small in the low-level but extended outward in the high-level. Besides, vertical ascending motion and the radial- and tangential-wind speeds increased with the increasing typhoon intensity, especially during the process of rapid intensification. Furthermore, the warm core of the typhoon increased from about 7 ℃ to 11 ℃ during the process with the warm core extending outward and towards the lower layer. All of the above structure changes contribute to the maintenance and development of typhoon intensity.