Effects of aerosols on temperature and wind in the planetary boundary layer simulated with ICON NWP model under different synoptic conditions

The error in short-term surface air temperature forecasts is significant in regions with high aerosol content. In addition, the use of aerosol climatologies that inaccurately describe aerosol properties can lead to substantial errors in meteorological forecasts on both global and regional scales. The purpose of this study is to assess the impact of the CAMS aerosol forecast on the accuracy of net shortwave radiation and air temperature calculations in the ICON model under cloudless conditions with different aerosol loads. Simulations were performed using the mesoscale NWP ICON model with the Tegen aerosol climatology, the CAMS aerosol climatology, and the operational CAMS aerosol forecast, allowing us to evaluate the sensitivity of model results to different aerosol representations.

Several case studies representing different synoptic situations over the Moscow region were selected, including high- and low-pressure systems and the passage of atmospheric fronts. The analysis focuses on clear-sky conditions in order to isolate the influence of aerosols from cloud-related radiative effects. Model results show that aerosols can change air temperature by more than 1 °C in the lower troposphere up to an altitude of approximately 800 hPa. Aerosols also significantly influence sensible and latent heat fluxes, as well as wind speed in the planetary boundary layer, particularly when aerosol optical thickness exceeds 0.4. These results demonstrate the importance of using realistic aerosol information for improving forecasts of boundary layer meteorological conditions.