# Influence of Atmospheric Flow Structure on Optical Turbulence Characteristics
## 5 Conclusions  
We performed a study of the atmospheric flows above the observatories and Lake Baikal. The WRF model accurately reproduced the airflows over the surface of the Lake, in the coastal area, as well as in the valley of River Angara. We should emphasize that this paper describes airflows in rough terrain with breeze air circulation, which significantly affects the vertical transfer of momentum and heat. The vertical transfer intensity depends on the large-scale air flow that suppresses vertical motions, as well as on the horizontal distributions of air temperature and local upward airflows. These physical representations were confirmed by a simulation of a boundary layer over mountainous terrain, described in [36]. Similar atmospheric situations were also simulated in [37]. [PERSON] et al. used the WRF model to diagnose breeze circulation and the interaction of large-scale, meso-scale and micro-scale movements in summer. Our results can be formulated as follows:  
1. We adapted the WRF model for the Baikal Astrophysical Observatory and Sayan Solar Observatory region. We shown that the YSU parametrization scheme reproduced the local air circulation during the day. The reproducibility of atmospheric parameters in the WRF model deteriorated under stable thermal stratification of the atmosphere. The same issue was pointed out in [38], which was a fine-resolution WRF simulation of stably stratified flows in shallow pre-alpine valleys. The authors found that the diurnal temperature range was underestimated in the WRF model;
2. The structure of turbulence over the BAO significantly depended on the orography and characteristics of meso-scale atmospheric disturbances (vortex and jet streams). The BAO is located at the periphery of a meso-scale atmospheric vortex structure with an anticyclonic direction of air flows in the daytime. An analysis of the energy spectra showed that the characteristic scales of this meso-scale vortex structure, whose center is formed north of the BAO, vary from 10 to 20 km;
3. We showed that the increase in image quality was due to weakening of the airflow over Lake Baikal, as well as a decrease in meso-scale wind speed fluctuations. In comparison with nighttime characteristics, the daytime spectral characteristics of the wind speed fluctuations, \(E_{n}\) and \(\int_{f_{1}}^{f_{2}}E(f)df/Int\), increased 2.5-3.3 and 2.0-3.4 times, respectively. The energy of high-frequency fluctuations in wind speed during the day also significantly increased. 4. We showed that the daytime spectrum of atmospheric meso-scale turbulence was close to the classical spectrum of strong turbulence (described by the \"\(-\)5/3\" law). At night and in the morning, the spectrum has a steeper slope on small scales. The spatial scales, based on which the spectrum changes its slope from \"\(-\)5/3\" to \(\sim\) \"\(-\)3\", are associated with the suppression of atmospheric turbulence in stably stratified atmospheric layers. The characteristic scales of the transition between different regions of the spectrum were 2-2.5 km. The obtained results are relevant for the development of methods to predict optical turbulence for ground-based telescopes, as well as the assessment of local transport of impurities [39; 40]. In the future, we plan to investigate the influence of baroclinic large-scale and meso-scale structures of atmospheric flow on dynamic and optical turbulence. These studies contribute to the development of methods for the diagnostics and prediction of astronomical image quality. Furthermore, WRF simulation is known to be sensitive to the type of atmospheric event and the combinations of physical parametrizations [41]. We need to evaluate the possibilities of modeling meso-scale processes above the observatory, taking into account different atmospheric events and parameterizations, including schemes based on the turbulent kinetic energy and its temporal transformations.