Comment on “Nucleation of Mesospheric Cloud Particles: Sensitivities and Limits” by L. Megner

Abstract

In my article "Minimal impact on condensation nuclei properties on observable mesospheric ice properties" (Megner, 2011, https://doi.org/10.1016/j.jastp.2010.08.006) I show that the observable bulk quantities of Noctilucent clouds are much less sensitive to the concentration of condensation nuclei than what previously has been believed. These results were challenged by Wilms et al. (2016, https://doi.org/ 10.1002/2015JA021764), who studied the effect of nucleation rate on cloud properties and find a sensitivity.In this comment I argue that the differences between the studies are less than they first appear: Both studies show a very limited sensitivity to ice condensation nuclei, especially when there are more than roughly 100 condensation nuclei per cubic centimeter. Observations do indicate that under normal conditions, there are at least around 100 particles per cubic centimeter in the region of formation, and thus that we are in the insensitive regime.

Dominant role of charged meteoric smoke particles in the polar mesospheric clouds

“…CC BY 4.0 License. observations, for reasons that are still under debate (Megner, 2011;Megner, 2019;Wilms et al, 2016;Wilms et al, 2019).…”

“…The lack of correlation between the ice particle radius r and the IWC is puzzling in the GS scheme (Megner, 2011;Megner, 2019;Wilms et al, 2016;Wilms et al, 2019), but straightforward in the CMN scheme: the ice particle radius r and concentration N are sensitive to the PMC height h rather than to the mean environment temperature T, while the IWC and the PMC thickness ∆Z are controlled by the mean environment temperature T, as shown in Figs. 6, 9, and 11.…”

Radar studies of ionospheric dusty plasma phenomena

“…The forming particles are transported in the atmospheric zonal and meridional circulation that are influenced by gravity waves. [5,6] The dust particles contribute to formation of icy particles when the temperature close to the mesopause reaches its frost point. The small dust acts as nucleation centres so the ice particles form faster than the homogenous condensation from gas phase does.…”

“…Models suggest that nucleation forms icy dust of radii 10-50 nm. [7] While models [5,6] assume that initial condensates of 0.2 nm size form in the meteor plumes, there is an uncertainty about the smallest size of the dust particles. Instruments on atmospheric rockets measure the impacts of charged dust particles.…”