台湾地形诱生中尺度系统对台风Meranti(1010)迅速加强影响的数值研究

The Effect of Mesoscale Systems Induced by the Topography of Taiwan on the Rapid Intensification of Typhoon Meranti(1010)

台风Meranti(1010)北上进入台湾海峡过程中迅速加强,登陆时达到其最大强度。利用中国气象局上海台风研究所最佳路径资料、NCEP GFS 0.5°×0.5°资料及中尺度数值模式WRF,诊断分析台湾地形诱生的中尺度系统对台风Meranti迅速加强的影响。研究发现,Meranti在进入海峡过程中,台湾地形在台湾海峡内诱生出中尺度涡旋,激发中尺度扰动波列,加强台风环流内的垂直运动。台风水汽、热量的收支诊断表明,强烈的上升运动使热量和水汽向上输送,加强台风内的积云对流和潜热释放,使其强度增强。计算台湾地形诱生中尺度系统与台风间的动能交换发现,中尺度系统通过加强垂直运动向台风中高层输送涡动动能,使中尺度系统动能向台风动能转换,为Meranti的迅速加强提供能源。敏感性试验表明,如果台湾地形不存在,中尺度系统消失,台风的水汽、热量的向上输送和积云对流明显减弱,Meranti则不能达到迅速加强标准。

Typhoon Meranti（1010） intensified rapidly after entering Taiwan Strait, and reached its peak just before landfall. Based on the best track data provided by Shanghai Typhoon Institute, China Meteorological Administration, the National Centers for Environmental Prediction Global Forecast System reanalysis data on 0.5？×0.5？ grids and numerical experiments, we investigate the effect of the mesoscale systems induced by the topography of Taiwan on the rapid intensification of typhoon Meranti（1010）. Results indicated that the topography of Taiwan induced a couple of mesoscalevortexes and disturbance wave trains, which helped intensify the vertical motion in the circulation system of typhoon after it entered Taiwan Strait. A diagnostic analysis of moisture and heat budgets demonstrates that the strong vertical motion is favorable for upward transport of heat and moisture, which promotes the development of cumulus convection. The latent heat release in deep cumulus convective clouds plays an important role for the intensification of Meranti. In addition, the kinetic energy exchange between Meranti and the mesoscale systems are calculated. The results indicate that the conversion from mesoscale kinetic energy to TC kinetic energy provides the main energy source for the rapid intensification of Meranti. The meso-scale systems induced by the topography of Taiwan intensify the vertical transport of eddy kinetic energy, leading to significant increases in TC kinetic energy and eventually the TC intensification. However, numerical sensitivity experiments show that the mesoscale systems will disappear if the topography of Taiwan is removed. In this situation, upward transport of moisture and heat and cumulus convection all distinctly decrease and TC Meranti cannot intensify rapidly.