A new Lagrangian in-time particle simulation module (Itpas v1) foratmospheric particle dispersion

Abstract. Trajectory models are intuitive tools for airflow studies. But in general, they are limited to non-turbulent, i.e. laminar flow conditions. Therefore, trajectory models are not particularly suitable for investigating airflow within the turbulent atmospheric boundary layer. To overcome this, a common approach is handling the turbulent uncertainty as a random deviation from a mean path in order to create a statistic of possible solutions which envelops the mean path. This is well known as Lagrangian particle dispersion model (LPDM). However, the decisive factor is the representation of turbulence in the model, for which widely used models such as FLEXPART and HYSPLIT use an approximation. A conceivable improvement can be using a turbulence parameterisation approach based on the turbulent kinetic energy (TKE) on high temporal resolution. Here, we elaborated this approach and developed the LPDM Itpas, which is online coupled to the German Weather Service's mesoscale weather forecast model COSMO. It allows for benefiting from the prognostically calculated TKE as well as from the high-frequent wind information. We exemplary demonstrate the model's applicability for a case study on agricultural particle emission in Eastern Germany. The results obtained are discussed with regard to the model's ability to describe particle transport within a turbulent boundary layer. Ultimately, the simulations performed suggest that the newly introduced method based on prognostic TKE sufficiently represents the particle transport.