Author response to interactive comment of H. Grothe and M. J. Rossi: “Spectroscopic evidence for large aspherical β-NAT particles involved in denitrification in the December 2011 Arctic stratosphere”

The investigation by Woiwode et al. (2016) represents an improved and updated reinterpretation of spectroscopic data on the existence of NAT particles in the Artic lower stratosphere. However, the whole evidence is based on the symmetric nitrate deformation band ν2=δs(NO3), which is in general the weakest band of the overall mid-infrared spectrum of nitric acid hydrates. Also, the differences between the ν2 bands of NAT (α, β) and NAD (α, β) are rather small. These differences may also be caused by different crystal structures or different morphologies and textures of the very same phase. This might be worth to be mentioned in the text. Unless concomitant changes in other parts of the mid IR spectrum are not conclusively observed, minor changes in one of the IR absorptions alone constitute weak evidence for the reasons cited above.