Molecular atmosphere uncertainties and calibration at CTAO

The Cherenkov Telescope Array Observatory (CTAO) has set ambitious goals for the systematic uncertainties on energy and flux reconstruction. Achieving these goals requires a detailed understanding of the atmosphere over the CTAO sites and the development of atmospheric characterization and monitoring methods. In this contribution, we focus on the molecular atmosphere. First, we discuss ongoing efforts to estimate the systematic uncertainties in CTAO science performance introduced by variations in atmospheric conditions over different timescales and the extent to which these can be reduced through atmospheric monitoring methods. We concentrate on the effects of variations in the density profile of absorbing molecules (due to seasonal variations or stratosphere-to-troposphere transport events) on measured Cherenkov light density on the ground, and ongoing efforts to assess uncertainties introduced by the use of seasonal or tailored nightly molecular profiles. Finally, we discuss the molecular atmosphere characterization suite implemented in the calibration pipeline of the Data Processing and Preservation System (DPPS) of CTAO.