## 3 Results and Discussion  
### Aerosols, Clouds, and Solar Fluxes during the Evolution of DAEC  
To have an easy view of the simultaneous evolution of cloudiness and aerosol loadings over the MB and its areas undergoing the African dust export, Figure 2 displays the geographical distributions of MERRA-2 DOD (left column) and ISCCP-H cloud amount (right column) during the three days of the examined DAEC, i.e., from 16 to 18 June 2016 (values are at 12:00 UTC). The dust export originates from Algeria and Tunisia and extends over the Gulf of Gabes, the Tyrrhenian Sea, Italy, and up to the Adriatic Sea on the first day (16 June 2016, Figure 2i-a) of the episode. Maximum dust loadings (DOD values up to 1.4, reddish colors) are noted on this day over the eastern Tunisian coasts and southern Tunisia inland. During the next two days (17 and 18 June 2016, Figure 2i-b,c) dust export moves eastward, with medium-to-high dust loadings (DOD around 0.5) covering the entire area of Greece and the Balkans. On these days, the maximum DOD values are reduced (reddish colors disappear and maximum DOD values reach up to about 1), compared to the first day of the DAEC, but high loadings cover wider areas of central and eastern MB. As shown in the right column of Figure 2, significant CFs (up to 0.9-1.0) are observed across the dust export path during the three days of the DAEC, against clear-sky conditions or low cloud cover over these areas before (on 15 June 2016) the dust episode, which provides evidence that the evolving Mediterranean dust episode plays a key role in the formation of both liquid- and ice-phase clouds by providing CCN and IN (Figure S7). This was also found by [50], where MODIS CF data were used, instead of those of ISCCP-H. In addition, as shown in this study (Figure 2) and by [50], the clouds over the areas that continued to undergo dust transport on the second and third day of the DAEC (17 and 18 June) either dissipate or diminish, with their cloud top height and temperature decreasing and increasing, respectively (Figure S8). The comparison between the ISCCP-H-based cloud cover of our Figure 2 and the corresponding ones of MODIS (Figure 5 in [50]) reveals that the two cloud products have similar geographical patterns, but ISCCP-H generally overestimates cloud amount, especially over N. Africa and the Aegegan Sea. Such an overestimation was also found in [73] who compared the ISCCP-H total cloud amount to that from the Cloud, Albedo, and Surface Radiation dataset from AVHRR data-edition 2 (CLARA-A2) surface-based observations at 22 meteorological stations in Europe, from the European Climate Assessment & Dataset (ECA & D). This overestimation may be associated with the viewing angle of the geostationary satellites or to the detection of cirrus clouds by satellites, which is not possible for surface observations. Additionally, a comparison between CFs from previous versions of ISCCP and MODIS datasets over Europe made by [60] revealed an overestimation of ISCCP in spring and summer. The DDREs are strongly dependent on three key aerosol (dust) optical properties, namely optical depth, single scattering albedo (SSA), and asymmetry parameter (AP), with DOD and SSA being the primary ones [55]. The geographical distribution of MERRA-2 SSA and AP at 550 nm during the three days of the examined DAEC, as well as one day before and after the DAEC, is shown in Figure S9 (DOD is shown in Figure 2 and has already been discussed). The SSA values over the dust export regions, during the three days of the DAEC, vary between 0.92 and 0.94, i.e., values that are representative of Saharan DAs [74]. Similar and slightly lower (0.91-0.92) SSA values are observed over N. Africa. Higher SSA values, up to 0.95 (yellowish colors) or 0.97 (reddish colors), are observed over Mediterranean Sea areas not undergoing dust export and dominated by non-absorbing sea-salt aerosols.