Diagnostic Study and Numerical Simulation on the Structure of Typhoon "Muifa" during Its Two Recurving Processes

A variety of data are used to analyze and study the two recurving processes of typhoon "Muifa", The results show that changes in the northwestern Pacific Subtropical high, the mid-latitude trough and cross-equatorial flows all have impacts on the two recurving processes of "Muifa". The internal TC structure such as the spiral cloud bands and eye wall changed little during the first recurving but they experienced huge changes during the second recurving with the formation of asymmetric structure, the replacement of eye wall and the merging of spiral cloud bands with eye wall. Numerical studies confirmed the above changes during the second recurving process. The mechanism study shows that the zonal and meridional components of environmental flow accounted for more than 83% of the steering flow for the first recurvature. For the second recurvature, the zonal component of storm-scale flow accounted for 23%-36%, while its meridional component accounted for 35%-47% of the steering flow.