In this paper, diagnostic analyses were conducted on two target typhoons Flo(9019) and Ed(9018) in SPECTRUM-90. The results show that the asymmetric dynamic structure of typhoon has been clearly displayed with the data of intensive sounding and dropsonde. At middle troposphere, the dipole flow pattern is composed of a pair of cyclonic and anticyclonic gyres around typhoon center. The typhoon move along with the ventilation flow between the gyres.
The result of numerical simulation has shown that the simulated track with the consideration of asymmetric struture in model's initial field is more accurate than that without such input. Using TCM-90 intensive observational data, the results indicate that typhoon motion is not only affected by the above mentioned asymmetric dynamic structure, but also by the asymmetric thermodynamic structure of instability stratification. With altering typhoon's asymmetric thermal structure, simulated typhoon track shows the obvious tendency of approaching instability area of thermal stratification. Many studies were carried out on the impact of tropical cyclone inner structure on cyclone motion since SPECTRUM-90. It is reviewed in this paper as well that different characteristics of unusual motion of SPECTRUM target typhoon, such as sudden turning, recurving and looping, are closely related to asymmtric structure when enviroment flow is weak.