Proceedings Article | 12 July 2023
KEYWORDS: Computed tomography, Atmospheric optics, Turbulence, Observatories, Astronomical imaging, Telecommunications, Astronomy, Machine learning, Atmospheric turbulence, Adaptive optics
The atmospheric turbulence measurement and characterization is an essential information for optical link (telecommunication, telemetry, time transfer, ...) and for high-angular resolution imaging in astronomy. Indeed, its impact on the light propagation degrades the bit error rate of optical communication signals and decreases the resolution of astronomical images. In this framework, since 2015, the Calern Atmospheric Turbulence Station (CATS) monitors optical turbulence conditions at the Calern observatory, from the ground to the top of the atmosphere during both daytime and nighttime. This instrumental platform is completely autonomous and is equipped with a set of complementary instruments using original techniques for monitoring optical turbulence during both daytime and nighttime. The Profiler of Moon Limb (PML) measures, from Sun or Moon observations, the vertical profiles of the refractive index structure constant C 2 n with a high vertical resolution (∼ 100m at ground level). The Generalized Differential Image Motion Monitor (GDIMM) monitors the wavefront coherence parameters (seeing, isoplanatic angle, coherence time, scintillation, outer scale) from bright stars observations. To control the monitors, a weather station provides the ground meteorological conditions (pressure, temperature, relative humidity, wind speed, wind direction and irradiance), and the nighttime cloud fraction is given by an all-sky camera. In addition, a turbulence forecasting system has been developed and integrated in the CATS station to daily predict daytime and nighttime meteorological and optical turbulence conditions for the next 48h. In this paper we present the CATS station and its last upgrades, and in particular the forecasting tool developed and test either on Cerro Pachon (Chile) and on Calern Observatory (France).
