The influence of reduced atmospheric transmission on the CTA-North performance

Cherenkov Telescope Array (CTA) is the next generation ground-based observatory for gamma-ray astronomy at very-high energies which will consist of the northern (CTA-N, La Palma, Spain) and southern (CTA-S, Paranal, Chile) arrays. The atmosphere, as an integral part of the Cherenkov telescope detector, has a great impact on the observed data, especially in means of reduced sensitivity. One of the main contributions to the systematic uncertainties arises from the presence of clouds. To minimize these systematic uncertainties a calibration of the detector response is of great importance. Here, the influence of cloud altitude and transmission on the CTA-N performance degradation using detailed Monte Carlo simulations has been investigated for the case that no measures are taken to characterize clouds and correct their effects. The degradation effect of the presence of clouds is primarily observed at low and middle energies but spans across the entire energy range.