Studying molecular profiles above the Cherenkov Telescope Array sites
Unitat de Fisica de les Radiacions, Departament de Fisica and CERES-IEEC, Universitat Autonoma de Barcelona,
Published online: 15 January 2019
The Cherenkov Telescope Array (CTA) will bring a whole new insight to the gamma-ray Universe. In order to fulfill its performance requirements, we need to understand and correct the atmospheric effects that influence the acquired instrument data. One such systematic effect is due to the varying molecular density profile with time. We have studied such profiles for both CTA sites using publicly available historical data assimilation archives. Our study reveals that we can distinguish at least three differentiated seasonal periods at the northern site and at least two at the southern site, that allow to model the molecular part of the atmosphere using average profiles, as done with current Cherenkov telescope projects. Seasonal transitions are smoother at the southern site than at the northern one. Moreover, the latter shows a greater amplitude in density variations at an altitude of 15 km. We also explored deviations of the molecular profiles with respect to their mean values using a 5-years data set and concluded that they are always found within specifications.
© The Authors, published by EDP Sciences, 2019
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.