Tomographic 3D reconstructions of artificial releases of SO2 in the atmospheric boundary layer

Turbulence in the planetary boundary layer controls the exchange fluxes of passive and active tracers between the Earth’s surface and the atmosphere. In climate and meteorological models, such effects of turbulence need to be parameterized, ultimately based on experimental data. A modeling/experimental approach was developed within the COMTESSA project to study turbulence statistics. Using controlled tracer releases, UV camera images and estimates of the background radiation, different tomographic algorithms were applied to obtain time series of 3D representations of the scalar dispersion. We used initially synthetic data to investigate different reconstruction algorithms with emphasis on algebraic iterative methods, studying the dependence of the reconstruction quality on the discretization resolution and the geometry of the experimental device in both 2D and 3D cases. For the iterative methods we assessed the computational aspects of the iterative algorithms focusing of the phenomenon of semi-convergence applying a variety of stopping rules. In addition to the synthetic studies, we present actual tomographic 3D reconstructions of artificial SO2 puffs using multiple camera measurements from the experimental campaigns in Norway.