We thank the reviewer for the careful reading of the manuscript and the constructive remarks. We have taken the comments on board to improve and clarify the manuscript. Please find below a detailed point-by-point response to all comments (reviewer comments in bold, our replies in italics). We are also providing in the GMD online discussion a revised manuscript that reflects the suggestions and comments of all the reviewers, where changes with respect to the original submission are highlighted.

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... e feel that this has resulted in a stronger manuscript. C1 GMDD Interactive comment Printer-friendly version Discussion paper Line 108: why is it called the "two-size moment method"? Line 114: "the NDF is reconstructed with a linear function". Linear with re-gard to whet? particle mass? The reviewer is correct and these points deserved a better explanation in the paper. We changed the text and now it reads in the following way: "While in the original formulation the internal variable is the size (described by the volume or the radius) of the particles and in each section two moments of the size distribution are used to reconstruct the NDF with a linear function of the size (hence the name two-size moment), here the NDF is defined as a function of particle mass." Equation 10 : there seems to be a subscripted left square bracket in each equation that should not be subscripted. Done, thank you! Line 195: It's interesting that your control volumes are cylindrical sections with a vertical axis, not with an axis paral-lel to the plume axis. This implies that the axes of stacked cylinders are not co-linear. Yet in the mass flux equation (eq. 12) you calculate the mass flux from one cylinder to another as something like pi*rËĘ2*w, where w is the vertical velocity. What sort of approximations are implied in eq. (12) if the stacked cylinders are not co-linear? The mass flux across the horizontal section, without approximations, is given by C2 GMDD Interactive comment Printer-friendly version Discussion paper