## 4 Results  
In the evaluation step, we investigated the relationships of all retrieved or calculated parameters: \(U_{\rm m}\), \(r_{\rm m}\), \(Cor_{\rm wr}\), \(DI\), \(SI\), and storm motion speed. Many parameters have no dependence on each other. Thus, only those parameters which have obvious relationships are presented in this section.  
The characteristics of decay are presented in Figure 7. Figure 7(a) shows that the decay index has a positive linear correlation with maximum wind. The correlation coefficient is 0.74. This feature coincides with the modified Rankine vortex statistics presented by [PERSON] et al. [11]. As shown in Figure 7(b), if wind speed decreases quickly with an increasing radius, the wind and radius are more linearly dependent. The correlation coefficient of \(DI\) and \(Cor_{\rm wr}\) is 0.72. The relationship between \(DI\) and storm motion are not related in general.  
Figure 6: Simulated symmetric wind fields within a 200 km radius for (**a**) Typhoon Jebi and (**b**) Hurricane Gaston. The spatial resolution is 1 km. Straight borders are same as those in SAR images.  
As shown in Figure 8, \(SI\) values increase with increasing maximum wind speeds. On average, the simulated wind fields of the TCs with high intensities tend to be more similar to SAR retrievals than the TCs with low intensities. This indicates that a strong TC generally has a symmetric wind field. This characteristic coincides with [PERSON] et al.'s investigation, although they used the asymmetry index (\(AI\)) and two different reconstruction models [25]. In their study, the \(AI\) values increase with increasing maximum wind speeds (see Figure 6d in [25]). In addition, according to the TC cases in our study, \(SI\) is independent of storm motion speed.  
Figure 8: The dependence of symmetry index on maximum wind speed, based on 41 TC cases’ wind field simulations and SAR retrievals. Black curve is the trend line. Red, blue and green dots stand for cases observed in the Atlantic, Eastern Pacific and Western Pacific, respectively.  
Figure 7: The dependences of decay index on (**a**) maximum wind speed and (**b**) correlation coefficient of wind speed and radius. Black curve is the trend line. Red, blue and green dots stand for the cases observed in the Atlantic, Eastern Pacific and Western Pacific, respectively.  
The comparison of \(U_{\text{m}}\) and averaged wind speed (\(U_{\text{Avg}}\)) in three sections of TC field, along with TC intensities and motion speeds, are illustrated in Figure 9. In order to ensure the comparability of each section, if a section in an image has less than 50% coverage, the image was removed. After removal, there were 22 TC cases left. These cases were then arranged in ascending order of TC intensity, as shown in Figure 9a, and in ascending order of motion speed, as depicted in Figure 9b. According to the comparison, there are 14, 2, and 6 highest \(U_{\text{m}}\) cases for the right, back, and left side, respectively. There are 14, 3, and 5 highest \(U_{\text{Avg}}\) cases for the right, back, and left side, respectively. The right side is the strongest section for the maximum and average. The back side is the weakest section. The maximum wind speed in each section increases with increasing TC intensity. The wind difference between the right and left side sections increases with increasing motion speed. In Figure 9b, the wind difference (black dashed trend line) and motion speed (blue line) have an obvious correlation. For the first 19 cases whose motion speeds are not large, the difference between motion speed and averaged wind difference is around 2.5 m/s. Their correlation coefficient is 0.76.  
Figure 9: (**a**) Maximum and averaged surface wind in three TC sections: right side, back side, and left side. Twenty-two TC cases are arranged in ascending order of TC intensity; (**b**) motion speed and averaged wind difference between the right and left side sections. TC cases are arranged in the ascending order of storm motion speed.