## 3 Results
### Variations in Infrared Radiance at NO 5.3 \(\mu\)m  
After determining the timing of the auroral event, we selected 32 datasets obtained from measurements performed by the SABER instrument using Channel 6. This particular channel primarily captures the NO 5.3 \(\upmu\)m radiation. The measurements were taken at approximately 55\({}^{\circ}\)N 160\({}^{\circ}\)W, spanning around 23:00 UT on 18 November to 18:00 UT on 23 November. By employing the limb sounding technique with SABER, which integrates the measurement path radiance along the line of sight, it was evident that the majority of the radiance contribution originated from the radiation at the tangent point. Hence, we plotted the temporal variations in radiance within the altitude range of 50-250 km at the tangent point. Figure 2 illustrates the observed changes in radiance over time. Due to the transition of SABER from the \"north-view\" mode to the \"south-view\" mode on 23 November, there were no available data after 18:00 UT near this time point. Additionally, SABER provided only a single orbital measurement on 18 November, resulting in an absence of data prior to 23:00 UT. As shown in Figure 2, the NO 5.3 \(\upmu\)m radiance was in a quiet period during 19 November, with the average radiance value of 1.41 \(\times\) 10\({}^{-4}\) W/m\({}^{2}\)/sr throughout the entire altitude region. The radiance value first reached its peak at around 120 km altitude after 12:00 UT on 20 November due to the disturbance caused by the aurora. It then gradually extended to other altitudes and elevated upward to 250 km by 22:00 UT, with a radiation enhancement spanning 50 to 250 km. The maximum radiance across the entire altitude region reached 3.38 \(\times\) 10\({}^{-3}\) W/m\({}^{2}\)/sr at 08:00 UT on 21 November of 123 km altitude, which was about 10 times larger than the average value during quiet periods. Thereafter, the radiance outside the altitude region of 100-125 km gradually decreased, while the radiance within this range remained high. This can be attributed to the dependence of reaction rates on temperature for NO (v = 1) [32; 53], despite the peak density of NO (v = 0) being concentrated around 105 km [19]. As a result, the radiance enhancement first appeared around 120 km and remained at a high level for about 40 h in this range. By 10:00 UT on 22 November, the entire altitude region returned to the quiet period level. However, at 18:00 UT on 22 November, the radiance suddenly increased again at around 120 km altitude and expanded within an approximately 20 km altitude region. Although the extent and intensity of this second auroral event were smaller than the first one, the radiance still reached 9.85 \(\times\) 10\({}^{-4}\) W/m\({}^{2}\)/sr at 13:00 UT on 23 November, about 7 times higher than the average value during quiet periods. This observation is consistent with the variations observed in the space environmental parameters in Figure 1, which were caused by a \"little peak\" in the solar wind speed on 22 November and the occurrence of a relatively weaker \"secondary aurora\" detected by the AE index around 16:00 UT on 23 November, and the occurrence of a relatively weaker \"secondary aurora\" detected by the  
November. Additionally, a trend of radiance recovery was observed after 17:00 UT on 23 November, despite the lack of data. Preliminary statistical analysis was conducted on the radiance data of Figure 2 by dividing the heights equally into four altitude regions: 50-100, 100-150, 150-200, and 200-250 km. The standard deviation (STD), minimum (MIN), and maximum (MAX) values of the radiance in these four height ranges were analyzed, and the results are shown in Table 1 and the dot-line chart in Figure 3.  
Figure 3: STD (black squares), MIN (red dots), and MAX (blue triangles) values for four different altitude regions.