Review Reports - Effects of Aluminum/Carbon and Morphology on Optical Characteristics and Radiative Forcing of Alumina Clusters Emitted by Solid Rockets in the Stratosphere

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1- I am not a native English speaker but the text needs English correction and some sentences are hard to follow.

2- Line 29 “by government”: you mean which government?

3- Line 51-52: What do you mean: “Their results showed Al2O3 particles were more efficient and pose fewer technology-specific risks than sulfate aerosols for the same radiative forcing.”

4- Use more references in your study, the number of references is too low.

5- Maybe it would be great if you mention how much Alumina (Al2O3) particles enter into the stratosphere every year or from every rocket? Is your study worth or the amount of Al2O3 is too low and not worth investigating?

6- Why did you not use any satellite data in your study?

7- AOD550nm mostly used for dust particles, maybe it will be great if you compare AOD550nm for dust and AL2O3.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This nice paper concerns the optical properties of alumina/carbon clusters ejected by rockets and their consequence on atmospheric radiative transfer, using different modeling approaches. The paper is well written and can be published if the following comments are considered.

Do the authors have also studied the effect in the troposphere, since the rockets first cross the troposphere before entering in the stratosphere (the authors speak of “from ground to the top of the atmosphere in lines 308-309) ?

References to stratospheric aerosols are not very suitable. There are some recent papers on volcanic aerosols and on non-sulfate stratospheric particles, manly coming from in situ measurements, that could be cited.

The yellow dots in figure 2 must be defined.

Line 184 : Can the author explain why they have considered 10 different clusters and not 5 or 20 or 100 ? Perhaps they can consider recent works on the number of different orientations or clusters that are necessary to retrieve mean optical properties.

Line 202: Because of increasing number of rocket launch per year, could this value strongly underestimate the reality of Al203 injection in the stratosphere?

Line 218: Should the authors consider the effect of the winter polar vortex that cleans the stratosphere by carrying down to the troposphere the stratospheric aerosols? Then, do the authors know if the possible deposition of these particles on the ices and snow in the polar region could decrease the Earth albedo?

Line 284: How the authors can be sure that this approximation represents the reality of the clusters in the stratosphere?

Figure 4b: The lighter grey dots are difficult to be seen (curve and legend).

Table 2: I am not sure it is necessary to provide 3 digits for the refractive index values, since these values can change from one author to another one ... (large set of values exist in the litterature for carbon particles).

Figure 8: Why are figures inserted in another figures (the smallest ones are difficult to read)?