## 4 Results and Discussion  
### Wind Speed and Air Temperature Effects  
In this study, we systematically analyzed the effects of the wind speed and air temperature on the surface temperature of airport pavements and the onset of icing. The experiments were conducted under six different air temperature conditions (\(-3\)\({}^{\circ}\)C, \(-5\)\({}^{\circ}\)C, \(-7\)\({}^{\circ}\)C, \(-10\)\({}^{\circ}\)C, \(-15\)\({}^{\circ}\)C, \(-20\)\({}^{\circ}\)C) and three wind speed conditions (2 m/s, 4 m/s, 6 m/s). 1. Effect of Wind Speed on Pavement Surface Temperature  
At higher air temperatures (\(-3\)\({}^{\circ}\)C to \(-5\)\({}^{\circ}\)C), the pavement temperature decreased rapidly at first and then stabilized, as shown in Figure 6a,b. The cooling rate during the first 15 min was approximately 0.30-0.32 \({}^{\circ}\)C/min, after which it significantly slowed to nearly 0.01 \({}^{\circ}\)C/min. At lower air temperatures (\(-7\)\({}^{\circ}\)C to \(-20\)\({}^{\circ}\)C), the pavement surface temperature exhibited a three-phase decline: an initial rapid drop, a subsequent stable phase, and a final accelerated drop, as illustrated in Figure 6c-f. This temperature variation was most pronounced at a wind speed of 6 m/s, indicating that higher wind speeds accelerated the cooling process, ultimately resulting in temperatures that were 6.6 \({}^{\circ}\)C to 10.6 \({}^{\circ}\)C lower than the ambient air temperatures. 2. Effect of Air Temperature on Pavement Surface Temperature  
Under varying wind speed conditions, lower air temperatures led to faster and more pronounced decreases in the pavement surface temperature, as illustrated in Figure 7. At lower air temperatures (\(-10\)\({}^{\circ}\)C to \(-20\)\({}^{\circ}\)C), the temperature drop exhibited a linear trend, with the cooling rate increasing as the air temperature decreased. For instance, at a wind speed of 2 m/s, the cooling rates were \(0.05\)\({}^{\circ}\)C/min, \(0.09\)\({}^{\circ}\)C/min, and \(0.1\)\({}^{\circ}\)C/min at \(-10\)\({}^{\circ}\)C, \(-15\)\({}^{\circ}\)C, and \(-20\)\({}^{\circ}\)C, respectively, as depicted in Figure 7a. This trend in cooling rate became more significant with an increasing wind speed. Figure 6: Effect of wind speed on pavement surface temperature: (**a**–**f**), respectively, show the results under air temperatures of \(-3\)\({}^{\circ}\)C, \(-5\)\({}^{\circ}\)C, \(-7\)\({}^{\circ}\)C, \(-10\)\({}^{\circ}\)C, \(-15\)\({}^{\circ}\)C and \(-20\)\({}^{\circ}\)C.  
Figure 7: Effect of air temperature on pavement surface temperature: (**a**–**c**), respectively, show the results under wind speeds of 2 m/s, 4 m/s, and 6 m/s. Effect of Wind Speed on Icing Onset Time  
As shown in Figure 8, the impact of the wind speed on the icing onset time was most noticeable at higher air temperatures (\(-3\)\({}^{\circ}\)C to \(-7\)\({}^{\circ}\)C). As the wind speed increased from 2 m/s to 6 m/s, the icing onset time decreased significantly. For example, at \(-3\)\({}^{\circ}\)C, raising the wind speed from 2 m/s to 4 m/s reduced the icing onset time by 29.4% to 35.7%, while increasing the wind speed further to 6 m/s shortened the time by an additional 8.3% to 22.2%. However, at lower air temperatures (\(-10\)\({}^{\circ}\)C to \(-20\)\({}^{\circ}\)C), the sensitivity of the icing onset time to variations in the wind speed diminished. Effect of Air Temperature on Lcing Onset Time  
As the air temperature decreased, the icing onset time was significantly reduced, as illustrated in Figure 9. For instance, at a wind speed of 2 m/s, when the air temperature dropped from \(-3\)\({}^{\circ}\)C to \(-20\)\({}^{\circ}\)C, the icing onset time decreased by 85.5% to 94.4%, with a maximum reduction of 25 min. This suggests that lower air temperatures enhance the temperature gradient between the water layer and the air, resulting in faster heat loss and a quicker onset of icing. Effect of air temperature on icing onset time  
Figure 8: Effect of wind speed on icing onset time. Figure 9: Effect of air temperature on icing onset time.