## 3 Discussion Results at the Hemispheric Scale
### Particle Size Distribution
The transport of \"giant\" mineral particles, which can be defined as particles with diameters exceeding 10 \(\upmu\)m, is rarely documented in the literature according to a recent study [102]. This study analyzes a specific Asian episode leading to the delivery of big particles in Korea thanks to mid-tropospheric strong winds. In Figure 6, the pattern close to Korea (showing that the maximum size bin is largely influenced by dust) confirms the possibility of long-range transport of \"giant\" particles far from emission areas. As mentioned in the Introduction, the added value of using models with fine horizontal resolutions [33] allows to better reproduce the processes of particle lifting like through the parametrization of deep convection processes activated in this version of CHIMERE [48]. However as suggested in [33], an explicit resolution of convection will enhance the capacity of the model to transport big particles on very long-range transport, but this remains too much time consuming so far for such large domains. Moreover, a recent study describing a conceptual model of dust dynamics showed that vertical transport can efficiently counteracts and limits the gravitational settling of coarse particles [103], according to Lidar observations in the frame of the SALTRACE experiment. Figure 5: Daily surface dust concentrations simulated by CHIMERE for the 16–19 March 2014 period. Figure 6: (Top) Map of the size bin number corresponding to the maximum surface concentrations for the mean total PM concentrations on 18 March 2014. (**Bottom**) Mean normalized size distributions for dust compared to black carbon and sulfate, averaged over the whole hemispheric domain for each model level [1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16] from the surface to the top on 18 March 2014. The evolution of the particle sizes is also shown in Figure 7 which provides an overview of dust concentration fields through latitudinal cross sections [0\({}^{\circ}\) N-90\({}^{\circ}\) N] averaged over boxes encompassing the Pacific and Atlantic Oceans, respectively, within longitudes ranges of [122\({}^{\circ}\) E-124\({}^{\circ}\) W] and [80\({}^{\circ}\) W-17\({}^{\circ}\) W]. Over the Pacific Ocean, concentrations peaks are located at 2-3 km in altitude at the interface with the boundary layer in mid latitude regions 35-40\({}^{\circ}\) N resulting mainly of the trans-Pacific transport of Asian dust emissions mixed with diluted Saharan dust transported by southwesterly fluxes. In Figure 7, the deep convection updraft flux integrated over the column is displayed as an indicator of the convective activity. A peak is observed over the Equatorial Pacific and an increase is also observed at mid latitudes, these convective processes could enhance the lift of dust particles within the free troposphere. Over the Atlantic Ocean the altitude of the maximum dust concentrations is lower, located within the marine boundary layer and very close to the Equatorial area at 5-10\({}^{\circ}\) N as the results of trans-Atlantic transport of Saharan dust by the trade winds (easterly flux). The dust concentrations peak are linked to the lowest contributions of fine particles (with diameter lower than 2.5 \(\upmu\)m), in background areas of the atmosphere the fine fraction contribution is generally higher due to the sedimentation and dry deposition of the biggest particles. In the lower troposphere, the lowest concentrations are simulated near the polar easterlies area (about 60\({}^{\circ}\) N) with a second concentrations peak between 2 and 3 km in altitude in the polar cell above 80\({}^{\circ}\) N; this specific location over the poles is confirmed during the AeroCom experiment [104]. A close look at vertical wind speeds shows slight positive vertical winds around 2-3 km in altitude (Figure S11 in Supplementary Materials) upper in altitude, which can explain this feature, generating stagnant conditions leading to higher concentrations.