The forecast for atmospheric and turbulence conditions above astronomical observatories is of interest to the astronomical community because it allows observations to be planned with maximum efficiency, a process called flexible scheduling. It can also be used to simulate long-term site testing to provide local information useful for the conception of focal and post-focal instrumentation. We have presented our forecasting tool in previous publications, but in this paper we focus on the importance of using local measurements to improve the predictive turbulence model and to better consider the local specificities of a given site, a process we call site learning. For this study, we use a local data base provided by the Calern Atmospheric Turbulence Station, which has been operational since 2015 at Calern Observatory. In addition, we use a set of several months of predictions to feed the turbulence model, taking into account daytime and nighttime conditions. This upgrade improves the quality of our forecasting by reducing the absolute bias between measurements and predictions from 25 to 50 per cent for each layer of the $C_n^2$, by 25 per cent for the seeing, and by 70 per cent for the isoplanatic angle.

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Free Space Optical (FSO) communication is an excellent tool for high-speed information transmission across a wide range of applications. It is now a key technology to overcome the rapidly increasing bandwidth limitations for space communications. However, FSO is directly affected by atmospheric propagation factors, such as meteorological conditions (cloud, fog, rain, etc.) and atmospheric turbulence conditions. A major challenge among these factors is atmospheric turbulence, which can lead to a phase distortion of the wavefront and to serious degradation of system performance. It is therefore crucial to overcome the effects of atmospheric turbulence in order to reliably monitor, assess the whole performance of the optical system and to fully exploit the potential of the FSO. Forecasts of meteorological and atmospheric turbulence conditions is of interest for optical link optimization because it can contribute to the efficient selection of the optical ground station network. It can also help to identify favorable time periods for laser optical links. In this study, numerical approach by Weather and Research Forecasting (WRF) model coupled with different turbulence models had been used. We compare the vertical profile of meteorological parameters (temperature, relative humidity, wind speed and wind direction) as well as the optical turbulence ( 2 ) conditions from the forecast model with the in-situ measurements, balloon-borne radiosoundings launched above Cerro Pachon Observatory in Chile. A new approach to estimate the outer scale ( 0 ) of turbulence is also presented and discussed.

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