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

Matthias Faust,Roger Funk,Ralf Wolke,Kerstin Schepanski,Steffen Münch

doi:10.5194/gmd-14-2205-2021

Abstract

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 the 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 could be the use of a turbulence parameterisation approach based on the turbulent kinetic energy (TKE) at high temporal resolution. Here, we elaborated this approach and developed the LPDM Itpas, which is coupled online to the German Weather Service's mesoscale weather forecast model COSMO. It benefits from the prognostically calculated TKE as well as from the high-frequency wind information. We 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.

Highlights

We are living in a polluted world
This is well known as the Lagrangian particle dispersion model (LPDM)
A conceivable improvement could be the use of a turbulence parameterisation approach based on the turbulent kinetic energy (TKE) at high temporal resolution

Summary

Introduction

We are living in a polluted world. Altogether, our industry, our mobility and our agriculture cause particulate matter emissions (Taiwo et al, 2014; Pant and Harrison, 2013; Kjelgaard et al, 2004) that decrease air quality and impact on human health in affected regions (Kim et al, 2015). Natural aerosol emissions like from soil erosion by wind can result in dusty haze plumes or mature dust storms which may locally cause poor air quality (Goudie, 2014). In central Europe, dust emissions can occur in agricultural environments. These are driven on the one hand by wind erosion and on the other hand by activities like tillage and harvest (Goossens, 2004). Wind erosion occurs predominantly in plains and on sandy soil under favourable conditions such as high wind speeds, low vegetation cover and low soil moisture. Dust emission by tillage is not a function of the wind velocity. Goossens (2004) estimated 4-timeshigher dust emissions caused by tillage operations than by natural wind erosion. Whereas wind erosion has been considered in aerosol–atmosphere models for several decades (e.g. Joussaume, 1990; Tegen et al, 2002; Huneeus et al, 2011), Published by Copernicus Publications on behalf of the European Geosciences Union

Methods

Discussion

Conclusion