【摘要】 为探究重灾台风0908号莫拉克(Morkot)成灾的内在原因,利用NCEP/NCAR1°×1°资料和WRF数值模式,以及观测分析和数值模拟方法,对"莫拉克"过台湾岛强度始终维持在960hPa不减的现象进行研究。观测分析发现"莫拉克"强度不减与其西南方向的0907号台风天鹅(Goni)相互作用有关,物理量诸如水汽、散度、涡度等持续从"天鹅"输入"莫拉克",如水汽输入层次主要集中在950～850hPa,600hPa以上很少;涡度(垂直速度)也存在低层正涡度(负散度)输送,高层负涡度(正散度)输送。利用WRF数值模式作控制试验和抹掉台风天鹅的敏感试验,试验结果表明有涡度、水汽通量、散度等物理量从天鹅向莫拉克输送卷入,从而对莫拉克过台湾岛强度的维持不减存在一定的支持作用。更多还原

【Abstract】 Typhoon Morakot(0908)caused severe damage.In order to explore the underlying reasons,the phenomenon that the intensity of the typhoon always remained around 960h Pa and did not reduce when it passed over the island of Taiwan is studied from both observational and numerical simulation results,by using the NCEP/NCAR1°×1°data and WRF numerical model.The observational analysis shows that the no reduction of Typhoon Morakot’s intensity was closely related to the interaction between Morakot and Goni(0907),which was in its southwest direction,and some physical quantities from Typhoon Goni were continuously transported into Morakot,such as the inputting of water vapor were mainly from 950 to 850 hPa,but rarely above 600h Pa.The transmission of vertical velocity existed in the whole layer,extending from 1000h Pa to 300h Pa.The positive vorticity(negative divergence)was transferred at the lower levels,and the negative vorticity(positive divergence)at the upper levels.Using the WRF numerical model for each control and sensitivity experiment in which Typhoon Goni was filtered,the results show that vorticity,moisture flux,divergence,and other physical quantities from Typhoon Goni were transported and involved in Typhoon Morakot,and thus they gave positive contribution to the maintenance and no reduction of Typhoon Morakot intensity when it passed over the island of Taiwan.更多还原