Having parameters representing closely the atmosphere and environment is of paramount importance to enable adaptive optics (AO) simulations that represent the final performances with a high level of fidelity. Also, when multiple AO-based projects are being developed in parallel for a single site, having a common basis, as much as possible complete and faithful to reality, is a very useful tool to be able to evaluate and compare their simulated performances. We present a full set of parameters dedicated to simulating AO systems for Paranal, obtained from on-site measurements whenever possible, including turbulence characteristics, laser guide star (LGS) and sodium layer features, and telescope environment. A particular attention has been put on validating the data measured on sky, on obtaining statistically meaningful data sets, and on identifying possible biases and environment or system specific effects that could affect the data. Emphasis is put on defining a set of requirements allowing to simulate and verify the AO performances, while keeping the number of these requirements to a realistic and workable level. This well-defined and limited set avoids overloading the simulation work while easing performances follow-up and comparison.
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