## 3 Results and Discussion
### Vertical Profiles of DA Effects on SW Radiation, Thermal Structure, and Atmospheric Dynamics
Indeed, a distinct dust layer extending from 37\({}^{\circ}\) N-5\({}^{\circ}\) E to 45\({}^{\circ}\) N-20\({}^{\circ}\) E (Figure 5a,e), namely from the Algerian coasts to the northwestern coasts of the Balkans, with \(\sigma_{\rm ext,dust}\) values up to 9.1 \(\times\) 10\({}^{-2}\) km\({}^{-1}\), is found at altitudes ranging up to about 4-5 km, while reaching the surface over areas between 38\({}^{\circ}\) and 41\({}^{\circ}\) N. The significant dust loadings in this layer produce, through absorption of solar radiation, a considerable radiative heating (Figure 5b) reaching values up to 4 W/m\({}^{2}\) at heights (up to about 7-8 km) and locations with high dust loadings, namely over areas extending from the coasts of Algeria (37\({}^{\circ}\) N-5\({}^{\circ}\) E) to Romania (45\({}^{\circ}\) N-22\({}^{\circ}\) E). It should be noted that the maximum DA SW radiative heating is not observed exactly where the maximum dust loadings occur, but slightly higher inthe atmosphere. This is evident in the aforementioned plot areas between 37\({}^{\circ}\) N-5\({}^{\circ}\) E and 45\({}^{\circ}\) N-20\({}^{\circ}\) E, for which the maximum dust loadings extend from the surface up to about 5 km, whereas the maximum SW heating is found between about 3 and 6 km. The different height of maximum dust SW heating and loadings is explained by the fact that the SW atmospheric DDRE is not only dependent on the dust loadings, but also on the available solar radiation, which is decreasing downward. As a direct consequence of the induced solar radiative heating, DAs induce atmospheric heating rates, up to 0.04 K/3 h within the dust layer (Figure 5c). However, it should be noted that the heating rates illustrated in Figure 5, as well as in Figures 6 and 7, refer to atmospheric layers with inhomogeneous depth, \(\Delta\)P, which increase with height (see Equation (2)). The atmospheric warming caused by the absorption of solar radiation by DAs, where they occur, decreases the magnitude of normal (negative) atmospheric lapse rates. At very few locations, characterized by very small lapse rates, this can lead to temperature inversions. Such reduced temperature lapse rates (down to \(-\)0.5 K/km) and intense temperature inversions (up to +9 K/km) are noted just below the elevated dust layer (white and red shaded areas in Figure 5d). The magnitude of the dust-induced atmospheric heating rates seems to be small compared to the magnitude of the prevailing atmospheric lapse rates, which shows that the interaction (absorption) of solar radiation with (by) dust is not the main driver for the formation of the atmospheric lapse rate during the DAEC, which may be driven by other mechanisms, such as the advection of heat or thermodynamic processes. This deserves to be further investigated using tools, such as the WRF-Chem model, accounting for all these mechanisms, and this is planned for a future study. A somewhat larger dust radiative heating, varying from \(-\)0.7 to +1.2 K at 12:00 UTC and from \(-\)2 to +2 K at 00:00 UTC, was reported in [45] where the WRF-Chem model was used to estimate the effect of a dust episode on the atmospheric temperature (from the difference between model output temperatures accounting and not accounting for DAs), but under clear-skies, which maximizes the heating rates produced by DAs. On the second day of the DAEC, the selected slant path extends from SE Tunisia to southern Italy (Sicily and Taranto), the Adriatic Sea, and NW Balkans (Figure 6e). Significant dust loadings, larger than those in the first day of the DAEC, occur over the continental N. African areas along the slant path, and off the Gulf of Gabes, from the surface up to 7 km, with maximum loadings (\(\sigma_{\rm ext,dust}\) up to 3.6 \(\times\) 10\({}^{-1}\) km\({}^{-1}\)) within the first two kilometers above the Libyan coasts (Figure 6a).