Validation of a radiative transfer model with measurements of UV radiation inside a commercial aircraft

A radiative transfer model for the determination of UV radiation on arbitrarily oriented surfaces is validated by spectral measurements taken directly on the inner surface of a cockpit window of an Airbus A321-231 during a flight from Frankfurt, Germany to Malaga, Spain on 23 August 2018. The simulations consider the UV spectral range from 290 to 400 nm and take into account both the measured spectral transmittance of a cockpit window as well as its construction-related orientation. Comparisons are performed for selected route segments with largely cloud-free conditions. The cruising level of the Airbus on these segments was nearly constant between 11.27 and 11.29 km. UV irradiance measurements at the cockpit window give values within a range of 19 and 26 W m(-2). The comparison of modelled and measured irradiances show a very good agreement, i.e. the relative differences between simulated and measured values range from -2.1% to +4.3%. In addition, horizontally and vertically oriented sensors are simulated for the same flight. The validation results generally underpin the application potential of the model. As an example of this, UV irradiances incident on differently oriented surfaces, as could occur inside and outside of a future flying taxi on a short-haul flight between Munich and Augsburg at low cruising level, are shown.