Influence of aerosols on atmospheric variables in the HARMONIE model

• The HARMONIE model is used for evaluating aerosol influence on weather conditions.
• The main impact of aerosols occurs along frontal zones in a form of mesoscale cells.
• Aerosols affect mainly weak precipitation by changing their life-time.

The mesoscale HARMONIE model is used to investigate the potential influence of aerosols on weather forecasts, and in particular, on precipitation. The study considers three numerical experiments over the Atlantic–Europe–Northern Africa region during 11–16 August 2010 with the following configurations: (a) no aerosols, (b) only the sea aerosols, and (c) the four types of the aerosols: sea, land, organic, and dust aerosols. The spatio-temporal analysis of forecast differences highlights the impact of aerosols on the prediction of main meteorological variables such as air temperature, humidity, precipitation, and cloud cover as well as their vertical profiles. The variations occur through changes in radiation fluxes and microphysics properties. The sensitivity experiments with the inclusion of climatological aerosol concentrations demonstrate the importance of aerosol effects on weather prediction.