Speaker
Description
For astroparticle projects that utilize the Earth's atmosphere as a calorimeter for detecting cosmic rays, real-time knowledge of atmospheric conditions and optical properties is essential. The ceilometer, a commercial meteorological lidar typically used for measuring cloud base height, vertical visibility, and cloud cover, represents a robust tool for characterizing the aerosol content of the atmosphere.
Currently, a ceilometer is deployed at the Observatory of the Astronomical Institute of the Czech Academy of Sciences in Ondřejov, operating in close proximity to the SST-1M Cherenkov telescope. We present an analysis of long-term ceilometer data from this device, including the development of a modified algorithm for aerosol layer detection and the evaluation of Vertical Aerosol Optical Depth (VAOD).
The VAOD is derived using both the Klett–Fernald method and an inverse lidar approach, allowing for a direct comparison of these techniques in terms of stability, accuracy, and applicability to ceilometer data. The study also includes an assessment of the long-term atmospheric conditions at the Ondřejov site, providing insight into aerosol variability and overall air quality.
Additionally, atmospheric data from the Copernicus program are incorporated to complement ground-based measurements and to validate the obtained results. The primary objective is to provide high-precision atmospheric calibration data for the analysis of SST-1M telescope observations and to establish a methodological framework for future deployments, including the planned installation of an identical ceilometer at the Roque de los Muchachos Observatory (La Palma).
The proposed approach enhances the reliability of energy reconstruction and cross-calibration of ground-based gamma-ray detectors by enabling continuous, automated monitoring of atmospheric transparency.