登陆台风 “凡亚比”（1011）合力散度分布及演变特征研究

本文利用1011号台风“凡亚比”高分辨率数值模拟资料及合力散度方程，诊断分析了“凡亚比”台风的合力散度水平分布及演变过程。首先将模拟的“凡亚比”生命史划分为五个阶段，然后计算各阶段整层垂直积分的合力散度，得到以下发现：在“凡亚比”快速增强阶段，台风中心附近首先出现合力辐合区，外围为合力辐散区；“凡亚比”成熟期和鼎盛期，合力辐合区呈现出以台风中心为圆心，半径约150 km的近似圆形分布，且中心附近辐合强度最大，向外逐渐减弱，外围合力辐散区呈螺旋云带状分布，宽度约200 km；“凡亚比”第一次登陆过程中，台风中心与合力辐合极值中心发生偏离，合力散度强度逐渐减小，对称结构被破坏；二次登陆后，辐散区迅速衰减甚至消失，但台风中心附近仍存在比较明显的合力辐合。“凡亚比”整个生命史中，合力辐合的平均强度普遍大于辐散的平均强度，前者与台风强度有显著的正相关关系。总体上，合力散度的强信号始终与台风环流系统相伴随，其演变能较好地反映出台风强度及结构的发展和演变。

Study on Total Force Divergence Distribution and Evolution Features of Landfalling Typhoon Fanapi (1011)

Using high-resolution simulation data for the landfalling typhoon Fanapi (1011) and the total force divergence equation, the horizontal distribution and evolution of the total force divergence/convergence of Fanapi are diagnosed. The lifespan of Fanapi is divided into five stages, and the vertical integration of the total force divergence/convergence is then calculated. During the initial rapid intensification stage, a convergence zone of the total force appears. In the mature and vigorous period, the total force convergence area appears as a roughly circular shape with a radius of about 150 km centered on the typhoon location. The convergence intensity is strongest around the typhoon center and decreases outward. On the periphery of the convergence zone lies the divergence zone, appearing analogous to the spiral cloud bands with a width of about 200 km. The convergence intensity decreases gradually, and its maximum deviates from the typhoon center when Fanapi makes its first landfall and the symmetrical structure is destroyed. After the second landfall, the divergence region shrinks rapidly, whereas the convergence area is relatively significant. Throughout the life history of Fanapi, the average convergence intensity is generally higher than that of divergence and has a significant positive correlation with the typhoon intensity. In summary, a distinct signal of the total force divergence/convergence always accompanies typhoon circulation, and its evolution is also capable of identifying the development of the typhoon intensity and structure.