This is the first time showing that long-term polarization observations with a Doppler lidar are possible. Second, the methodology could be applied to other HALO lidars and thus expand the capabilities for observing atmospheric aerosol. Third: It shows that Finland (any maybe whole Scandinavia) is during summer time most of the time dominated by Pollen or other biogenic aerosol, something which is maybe attributed to the continental background class used in CALIPSO, and not yet fully understood.

Tornadoes are having impact on peoples live and are in a general interest.

This paper demonstrates that lidar CO₂ measurements can substantially complement current passive remote sensors by providing measurements above clouds and within cloud gaps. Furthermore, lidar provides data at high latitudes where spectroscopy suffers from low solar illumination and challenging albedo variations. This is of particular importance in the context of "Arctic amplification". The paper paves the way for future CO₂ and also CH₄ lidar measurements from satellites.