Based on the intensive observations at automatic weather stations over Fujian province,NCEP/NCAR reanalysis with 0.5°×0.5° resolution and simulations from WRF mesoscale numerical model,we have performed an analysis of the features of surface rainfall in the ex-treme heavy rainfall event induced by Typhoon"Meranti"(1614)in Fujian and the detailed three dimensional structures of airflow,tempera-ture and moisture,energy,dynamic and thermodynamic fields,and conducted a preliminary investigation of the reason why the extreme heavy rainfall of the typhoon spiral rain band locates in the northeast quadrant after the typhoon landfall.The main results are as follows.(1)Before typhoon's landing,it showed warm core,moist core and positive vorticity column features in the lower to mid-high levels of the typhoon circu-lation and the funnel-shaped structure of pseudo-equivalent potential temperature(θse)in the mid-high level.The radial inflow obviously per-sists in the boundary level.The asymmetry of typhoon spiral rain band is weak.Only in the southwest quadrant of the typhoon,the intensity and area of spiral rain band are not as strong and wide as in other quadrants.(2)After typhoon's landing,its warm and moist core disappears fast and the horizontal range of positive vorticity column decreases gradually.The funnel-shaped structure of θsein the mid-and upper-level touches down to the ground.The deep radial outflow begins to prevail in the southwest quadrant and the radial inflow start to weaken in the northwest quadrant.However,the deep radial inflow persists in the east and northeast quadrants,which leads to a spiral rain band mainly lo-cating in the northeast quadrant.(3)The severe precipitation in the spiral rain band mainly locates in the northeast quadrant after typhoon's landing,which is related to the decentration of tangential waves with wave numbers 0-3 in the typhoon circulation.(4)The extreme heavy rain in Xiamen and Quanzhou is mainly caused by typhoon inner core rain band,and that in Ningde and Fuzhou predominantly results from ty-phoon spiral rain band.It is also found that the environments and physical mechanisms are different for the formation of extreme heavy rainfall in the typhoon inner core and spiral rain band.%利用福建省地面加密自动站观测资料、NCAR/NCEP再分析资料(0.5°×0.5°)与WRF中尺度数值模式的模拟结果,对2016年第14号台风"莫兰蒂"引发的福建特大暴雨过程的地面降水特征以及台风登陆前后其流场、温湿场、能量场与动力、热力等三维精细结构特征进行了分析,并初步探讨了台风登陆后螺旋雨带强降水主要位于台风东北侧的原因.结果发现:(1)台风登陆前,台风底层到中高层为暖心、湿心和正涡度柱结构,中高层假相当位温(θse)为漏斗状结构,台风边界层存在明显的入流,台风螺旋雨带的非对称性相对较弱,仅在有多重气流结构的台风西南侧其螺旋雨带强度相对较弱且范围相对较小.(2)台风登陆后,台风的暖心、湿心结构特征很快消失,正涡度柱水平范围收缩,台风中高层θse漏斗状结构触地,台风西南侧转为较深厚的出流,西北侧低层入流减弱,而台风东侧和东北侧维持深厚入流,台风螺旋雨带主要位于台风东北侧.(3)台风登陆后螺旋雨带强降水主要位于台风的东北侧,这与台风环流内0-3波形成的"偏心"结构有关.(4)厦门至泉州一带大暴雨由台风内核雨带造成,福州至宁德一带大暴雨由台风螺旋雨带造成;台风内核雨带与螺旋雨带强降水形成的环境条件和物理机制存在一定差异.
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