Dear Authors,

Thank you for submitting your revised manuscript that has addressed the referees' comments and questions. I am happy to accept your work for publication in ACP.

In the Introduction, and elsewhere, there are some other well-cited studies of the effects of chemical aging on the ice nucleation properties of mineral dust that you might consider including and discussing briefly. The FROST-2 campaign at LACIS condensed sulphuric acid onto mineral aerosol particles, and found this inhibited the deposition freezing, while immersion freezing was partially decreased.

Sullivan, R. C.; Petters, M. D.; DeMott, P. J.; Kreidenweis, S. M.; Wex, H.; Niedermeier, D.; Hartmann, S.; Clauss, T.; Stratmann, F.; Reitz, P.; Schneider, J.; Sierau, B. Irreversible loss of ice nucleation active sites in mineral dust particles caused by sulphuric acid condensation. Atmos. Chem. Phys. 2010, 10, 11471–11487.
Reitz, P.; Spindler, C.; Mentel, T. F.; Poulain, L.; Wex, H.; Mildenberger, K.; Niedermeier, D.; Hartmann, S.; Clauss, T.; Stratmann, F.; Sullivan, R. C.; DeMott, P. J.; Petters, M. D.; Sierau, B.; Schneider, J. Surface modification of mineral dust particles by sulphuric acid processing: implications for ice nucleation abilities. Atmos. Chem. Phys. 2011, 11, 7839–7858, doi:10.5194/acp-11-7839-2011.
Niedermeier, D.; Hartmann, S.; Wex, H.; Clauss, T.; Kiselev, A.; Sullivan, R. C.; DeMott, P. J.; Petters, M. D.; Reitz, P.; Schneider, J.; Mikhailov, E.; Reimann, B.; Bundke, U.; Stetzer, O.; Sierau, B.; Shaw, R. A.; Mentel, T. F.; Stratmann, F. Experimental study of the role of physicochemical surface processing on the IN ability of mineral dust particles. Atmos. Chem. Phys. 2011, 11, 11131–11144.

In related experiments, Arizona test dust (which Atkinson et al. later found contains K-feldspars, which explains the high INA of this dust) was exposed to nitric acid vapor. This was found to impair deposition freezing while immersion freezing was unaltered. The possible reasons for the differences between the effects of sulphuric and nitric acid were discussed. It was concluded that the nitric acid reaction products dissolve off the surface in the immersion mode to either re-expose the original ice active sites, or new surface sites if irreversible chemical alteration of the surface resulted.

Sullivan, R. C.; Miñambres, L.; DeMott, P. J.; Prenni, A. J.; Carrico, C. M.; Levin, E. J. T.; Kreidenweis, S. M. Chemical processing does not always impair heterogeneous ice nucleation of mineral dust particles. Geophys. Res. Lett. 2010, 37, doi:10.1029/2010GL045540.

The role of the reaction product versus chemical alteration of surface sites was then investigated by Sihvonen et al.:
Sihvonen, S. K.; Schill, G. P.; Lyktey, N. A.; Veghte, D. P.; Tolbert, M. A.; Freedman, M. A. Chemical and physical transformations of aluminosilicate clay minerals due to Acid treatment and consequences for heterogeneous ice nucleation. J. Phys. Chem. A 2014, 118, 8787–96, doi:10.1021/jp504846g.

Finally, just recently a study on the effect of secondary organic aerosol coatings on the INA of mineral dust concluded that there was no discernible effect in the immersion freezing mode. Similar to the nitric acid aging, presumably the SOA is dissolved off the surface when immersed in droplets to uncover the surface sites. This paper was just recently accepted for publication in ACP:
Heterogeneous Ice Nucleation Properties of Natural Desert Dust Particles Coated with a Surrogate of Secondary Organic Aerosol
Zamin A. Kanji, Ryan C. Sullivan, Monika Niemand, Paul J. DeMott, Anthony J. Prenni, Cedric Chou, Harald Saathoff, and Ottmar Möhler
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-905, 2018
Revised manuscript accepted for ACP (discussion: closed, 4 comments)

Best regards,
Ryan Sullivan
ACP Co-Editor