# Classification of Tropical Cyclone Tracks in the Northwest Pacific Based on the SD-K-Means Model
## 4 Results Analysis  
The proposed SD-K-Means clustering model divides TC tracks in the NWP between 2000 and 2022 into four distinct categories, labeled as Cluster 0, Cluster 1, Cluster 2, and Cluster 3. The specific classification outcomes are presented in Figure 3, with the number of TCs per cluster as follows: Cluster 0 contains 274 TCs, Cluster 1 contains 79 TCs, Cluster 2 includes 8 TCs, and Cluster 3 comprises 146 TCs. Each cluster exhibits distinct track patterns and characteristics. The following sections provide a detailed analysis and interpretation of the clustering results. Cluster 0: This cluster primarily consists of TCs that exhibit two main patterns:  
TCs that follow the first pattern are generated in the NWP and land on Hainan Island; or they turn near eastern China, initially move westward before curving northeastward near 20-30\({}^{\circ}\) N and 120-125\({}^{\circ}\) E, typically along the eastern coast of China. These TCs often impact northeastern China, the Korean Peninsula, and Japan. TCs following the second pattern, generally forming in the NWP around 130-140\({}^{\circ}\) E, move westward across the SCS and primarily impact Hainan, Guangdong, Vietnam, and Laos. In terms of intensity, \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Clustering Model** & **K-Means** & **DBSCAN** & **DTW-Based K-Means** & **SD-K-Means** \\ \hline DBI & 1.6221 & 0.9268 & 1.2229 & 1.1422 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of DBI values of multi-clustering models. TCs in this cluster exhibit moderate growth and shorter durations of maximum intensity compared with those in Cluster 1. Cluster 1: This cluster is composed almost entirely of turning-type TCs. These TCs also exhibit initial westward movement, followed by a turn to the northeast. However, from the position of the central track in Figure 4, it can be found that compared with the turning TCs in Cluster 0, the deflection positions of the turning TCs in this category are mostly near 20-30\({}^{\circ}\) N and 125-135\({}^{\circ}\) E, which are relatively further east, that is, relatively farther from the eastern coastline of China, and the straight distance to the west is shorter. From the perspective of activity and impact areas, TCs in this category mostly affect the Korean Peninsula and Japan. These TCs originate further east in the NWP (140-170\({}^{\circ}\) E). Figure 3: TC track clustering results. The black solid dots represent the TC formation locations, and the TC tracks of different colors represent the current TC intensities. The specific intensity levels are shown in the legend in the upper left corner of the figure. The classification is based on the RSCM-Tokyo intensity level classification standard. Compared with Cluster 0, they show faster intensification and longer periods of high intensity, indicating stronger storm systems overall. Cluster 2: This cluster contains the fewest TCs. These storms are typically generated east of 150\({}^{\circ}\)E in the central Pacific and rarely impact the Chinese coast. Most remain over the open ocean, though some may influence Japan. These TCs are among the strongest in terms of intensity and destructive potential. Cluster 3: Cluster 3 includes two typical TC types: Northeastward-moving TCs and Hainan-landfalling TCs formed in the SCS. The northeastward-moving TCs originate in the central NWP (east of 130\({}^{\circ}\) E) and primarily impact Japan. The Hainan-bound TCs, generated in the SCS (west of 120\({}^{\circ}\) E), travel westward without turning and mainly affect Hainan, Guangdong, Vietnam, and Laos. From an intensity perspective, TCs in this cluster display slower intensification and shorter durations of peak intensity, especially for those making landfall in Hainan, which tend to be weaker and shorter-lived. Next, this chapter analyzes the four types of TCs from multiple aspects, such as TC intensity and destructive potential, activity season, and landing situation.