## 4 Results
### Intensity 557.7 nm  
Figure 6 demonstrates annual variations in average nighttime I 557.7 nm airglow as obtained from the SABER, FPI and NRLMSIS model for 2017-2021 over the south of East Siberia. Figure 7 shows annual variations of monthly average nighttime intensities, the same as Figure 6. Minimal values of I 557.7 nm are observed in the winter-spring season, and maximal I 557.7 nm are essentially seen in summer and autumn. Seasonal variations of intensity are actually the same for different instruments from early winter to early summer and different in summer and autumn (Figure 6). Winter airglow intensities are \(\sim\)200-300 R, the intensity begins to decrease as the spring season begins, and minimal values of \(\sim\)100 R are reached in April. From spring to summer, we can see a sharp growth of intensity, up to 400 R in early summer, after which a convergence in data from different instruments begins. From satellite data, the intensity continues to enhance to maximal values of \(\sim\)500 R in July-August, and from ground data, the intensity begins to vary within 300-450 R. According to all instruments, intensity starts to decrease in August-September, but from interferometer data, it increases again in October and November, while SATI and SABER show a decrease in the intensity. The greatest discrepancy in the observed intensity is seen in November amounting to almost 200 R. As winter sets in, I 557.7 nm from all instruments become almost the same, reaching 200-300 R. According to NRLMSIS data, intensity variations do not exceed 200 R throughout the year. It should be noted that except for the April minimum, at all other times, the model intensity is consistent with the average monthly values obtained with the interferometer. Considerable differences are seen in June and November. In addition, the intensity obtained using the model has a local maximum  
Figure 5: Monthly average altitude and average statistical deviations of temperature minima from 2017 to 2021 from SABER (red) and NRLMSIS model (blue) data.  
in spring, when we observe the global minimum of intensity according to all instruments in question.  
Figure 8 shows the comparison of intensity peak positions in the height profile averaged over the month from data by SABER and NRLMSIS. One can note that from January to June, the behavior of both plots is relatively similar, the height of the airglow maximum growing from January to a maximum of 95.5-96 km in April and going down to summer minima of ~94 km in April-June. From satellite data, in the second half-year, the maximum altitude of the airglow peak of ~95 km is reached in August; according to model data, it is reached in September-October. December and January monthly average altitudes of the intensity maximum are significantly lower from model data than those from satellite data (92 and 94 km, respectively).  
Figure 6: Annual average intensity from 2017 to 2021 from SABER (red), FPI (green) and NRLMSIS model (blue) data.  
Figure 7: Monthly average I 557.7 nm from 2017 to 2021 from SABER (red), FPI (green), NRLMSIS model (blue) and SATI (violet) data and their deviations.  
Another interesting result is the asymmetric behavior of intensity and temperature related to changes in the circulation pattern. During circulation restructuring in spring, we can see a significant decay of airglow intensity and considerable temperature variations. In autumn, the circulation pattern changes without critical intensity decreases and temperature variations. The shift in the altitude of the intensity maximum to August in Figure 8 should indirectly spur the researchers to further search for the reason for this asymmetry.