Dust Aerosol Radiative Effects During a Dust Event and Heatwave in Summer 2019 Simulated with a Regional Climate Atmospheric Model over the Iberian Peninsula

Mineral dust particles significantly influence the Earth’s climate through direct and semi-direct radiative effects. This study investigates these effects and their meteorological impacts during a dust intrusion and heatwave over the Iberian Peninsula in summer 2019 using a regional climate model. Three simulations with different spectral nudging configurations are evaluated. During the central period, the mean direct and semi-direct radiative effects in the shortwave spectrum at the top of the atmosphere (bottom of the atmosphere) are −0.4 ± 0.4 (−3.9 ± 2.3) Wm−2 and +0.1 ± 1.7 (−0.1 ± 1.9) Wm−2, respectively. In the longwave spectrum, these effects are +0.1 ± 0.1 (+0.3 ± 0.1) WmWm−2 and 0.0 ± 0.6 (+0.9 ± 1.1) Wm−2, respectively. The semi-direct effect mitigates 18.8% of the dust-induced warming in the full atmosphere and alters meteorological variables. The liquid water path decreases by −0.2 ± 4.5 mg m−2, the cloud fraction in the upper (lower) troposphere reduces (increases) by −0.2 ± 1.2 (+0.1 ± 1.3) %, and the near-surface air temperature drops slightly by −0.2 ± 0.2 °C. The results highlight substantial spatial variability and underscore the importance of considering semi-direct radiative effects in radiative analysis.