## 3 Results
### Comparative Analysis of Temperature Profiles from the Surface to 3000 m  
Figure 6 shows the applicability of ERA5 temperature at various heights. Though the near-surface temperature is mainly influenced by solar radiation and weather conditions, the topography and vegetation cover in the mountainous areas of southeast China are also major factors. The red lines in Figure 6(a1-i1) indicate the temperatures of the ERA5  
Figure 4: (**a1–f1**) Wind rose plots of mean wind speed observations in 16 directions at each height compared to the ERA5 reanalysis data; (**a2–f2**) scatter plots of wind direction observations at each height compared to the ERA5 wind directions.  
reanalysis data at each height, and the blue lines indicate the temperatures obtained from the MWR observations at each height. Overall, the ERA5 reanalysis data at 0, 50, 100, and 200 m show some small deviations from the MWR observations, the ERA5 reanalysis data at 1000 m and 1500 m agree well with the MWR observations, and the ERA5 reanalysis data at 2000 m and 3000 m show large deviations from the MWR observations. In Figure 6(a1), a large deviation is evident. In the comparison of surface temperatures, the ERA5 reanalysis data have deviations in some periods, and the temperatures of the ERA5 reanalysis data are significantly lower than those of the observations in the period from 1 to 17 May, while it is slightly warmer than the observations from 22 to 26 May. Moreover, the ERA5 reanalysis data was slightly higher than the observed temperatures during the heavy rainfall period from 18 to 22 June. However, the ERA5 data show a trend of temperature variations at the mountain site, and the temperature of the ERA5 reanalysis data deviates slightly from the MWR observations due to the local circulation and the rapid change in regional weather phenomena.  
Figure 5: _Cont._  
In Figure 6(a1-e1), the deviations of the ERA5 reanalysis data are generally higher than those of the MWR observations before 20 May, and lower than those of the MWR observations after 20 May, and the temperature of the ERA5 data is higher than that of the observed data on 28 July, when southeast China was affected by the typhoon. In Figure 6(f1,g1), the ERA5 reanalysis data and the observed temperatures from the MWR show a good agreement at 1000 m and 1500 m. Under the influence of the typhoon, the temperature observations after July 28 are lower than the ERA5 temperature data at altitudes other than 1000 and 1500 m, and the ERA5 data temperatures at altitudes of 1000 and 1500 m are less affected by the typhoon. A poor correlation between the ERA5 reanalysis data and the observations are found at 2000 m and 3000 m. The systematic deviation is 2 K at 2000 m and more than 5 K at 3000 m. In Figure 6(h2,i2), the scatter plot reveals a discrepancy between the actual data points and the red dotted line, as the fitted line exhibits a considerable displacement from its corresponding reference line. However, the temperature trend of the ERA5 reanalysis data is improved in Figure 6(h1,i1), and the error only occurs in special weather conditions. The temperature of ERA5 reanalysis data are well correlated in the middle and bottom layers over mountainous areas. However, in the upper layers above 2000 m, there is a phenomenon whereby the higher the altitude, the larger the deviation. These large temperature deviations at higher altitudes have been mentioned in previous studies [13]. The accuracy of the ERA5 reanalysis data itself is also insufficient, and although the resolution has reached 0.25\({}^{\circ}\)\(\times\) 0.25\({}^{\circ}\), the accuracy of 31 km also makes it unable to precisely describe the exact meteorological elements at a location. We also compare the observations with the ERA5 data through the U,V component of the wind, as detailed in Figure S7.