## 3 Results  
The final classification model's ROC curve is displayed in Figure 4. The AUC values of the training and test sets in this study are 0.986 and 0.975, respectively, and much higher than the AUC value of a random prediction (0.5). This demonstrates how accurate the MaxEnt model was at forecasting the PP distribution in the study area. The PP distribution of Arxan is shown in Figure 5a. The PP values of 92 boreholes and 16 investigation points with permafrost were mainly distributed in the high-value domain, while the PP values of 109 boreholes without permafrost were mainly distributed in the low-value domain (Figure 5b,c). Among the 109 boreholes without permafrost, only one borehole has a PP value higher than 0.5, accounting for 0.9% of boreholes without permafrost. We took 1% as the tolerable error limit; so, we chose 0.5 as a cut-off point for the PP value. The area with a PP value lower than 0.5 was considered as a low probability of permafrost. Additionally, PP values between 0.5 and 1.0 were separated into five parts at 0.1 intervals to evaluate the PP distribution in the study area. Figure 3: Technical flowchart. The distribution of permafrost in Arxan is greatly affected by geographical factors (Figure 5a). The terrain of the study area is high in the middle and low in the west and southeast, and the permafrost is mainly distributed in the middle and west of the study area. It can be seen that the permafrost is mainly distributed in the GKM from the northeast to the southwest, followed by the low-altitude area in the northwest. It is only distributed in a small amount in the southeast of the GKM. PP gradually decreases from the middle to the west. The area with PP \(>\) 0.5 is 3079.6 km\({}^{2}\), accounting for 41.9% of the total study area. Among them, the area with PP \(>\) 0.8 is mainly distributed in the high-altitude area in the middle and southwest of the study area, accounting for 13.1% of the total study area. The area with a PP value of 0.6-0.8 accounts for 18.  
around the area with PP > 0.8. The area with a PP value of 0.5-0.6 is widely distributed in the west and north of the study area. Approximately 28% of the study area has a PP value distributed between 0 and 0.1 (Figure 6a). For areas with PP values higher than 0.5, the area with PP > 0.9 is the smallest, and the area of the remaining PP value intervals have a similar area proportion. The distribution of permafrost in the study area follows a vertical zonation law and is affected by altitude (Figure 6d). On the whole, for the area with PP < 0.8, the higher the PP value, the higher the altitude. The area with PP \(\leq\) 0.5 is widely distributed in the southeast part of the study area (Figure 5a), and the elevation in this part is mainly between 500 and 1600 m. The frequency increases with the elevation and reaches its peak at 1300 m. For the area with 0.5 < PP \(\leq\) 0.7, the altitude is mainly between 1100 and 1400 m, and the frequency peak is about 1350 m. The area with 0.7 < PP \(\leq\) 0.8 is mainly distributed between 1300 and 1500 m, and the frequency peak is about 1450 m. The area with PP > 0.8 is not distributed at higher altitudes, and the altitude distribution of the 0.8 < PP \(\leq\) 0.9 area is closer to that of the 0.5 < PP \(\leq\) 0.7 area. The area with 0.9 < PP \(\leq\) 1 is not only distributed in high altitude levels, but also distributed in low altitude levels. These low altitude areas are mainly distributed in the northwest of the study area. The cold air in the Mongolian Plateau is blocked from moving eastward, and it accumulates in this area. At the same time, the grass and shrub plants in this area are dense and keep the ground at a low temperature. These conditions are conducive to the preservation of permafrost. In general, for the area with 0 < PP \(\leq\) 0.8, the higher the PP value, the higher the altitude; the altitude distribution of the area with PP > 0.8 is wide. Areas with different PP values have significant differences in aspect distribution (Figure 6b).