Characteristics of the upper-level outflow and its impact on the rapid intensification of Typhoon Roke (2011)

In this study, we investigate the structural characteristics of upper-level outflow and its impact on rapid intensification (RI) Typhoon Roke (2011), which experienced an evident transformation from equatorward to poleward during RI period. The simulations by Weather Research Forecasting Model suggest that extends 100 hPa 150 hPa, with warm core at around hPa. is enhanced ahead typhoon intensification, closely related outflow-environment interaction. Further analyses indicate early stage (2011) before RI, strong updraft south center are enhanced, favoring onset RI. During period, divergent flow near entrance southwesterly jet in front trough, induces outflow. eddy flux convergence angular momentum inward propagated a 1000-km radius further enhances leads development vertical motion north center. Then intensifies rapidly. Simultaneously, shallow weak positive potential vorticity (PV) anomaly increases inner-core PV, sustained (2011). After reaches peak intensity, intensity decreases due increase wind shear approaching jet. It indicated interaction between upper-tropospheric trough has significant influence TC.