Atmos. Chem. Phys. Discuss., 10, 3605-3625, 2010
www.atmos-chem-phys-discuss.net/10/3605/2010/
doi:10.5194/acpd-10-3605-2010
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
On microphysical processes of noctilucent clouds (NLC): observations and modeling of mean and width of the particle size-distribution
G. Baumgarten, J. Fiedler, and M. Rapp
Leibniz-Institut für Atmosphärenphysik e.V., 18225 Kühlungsborn, Germany

Abstract. Noctilucent clouds (NLC) in the polar summer mesopause region have been observed in Norway (69° N, 16° E) between 1998 and 2009 by 3-color lidar technique. Assuming a mono-modal Gaussian size distribution we deduce mean and width of the particle sizes throughout the clouds. We observe a quasi linear relationship between distribution width and mean of the particle size at the top of the clouds and a deviation from this behavior for particle sizes larger than 40 nm, most often in the lower part of the layer. The vertically integrated particle properties show that 65% of the data follows the linear relationship with a slope of 0.42±0.02. For the vertically resolved particle properties (Δz=0.15 km) the slope is smaller and only 0.39±0.03. We compare our observations to microphysical modeling of noctilucent clouds and find that the distribution width depends on turbulence, the time that turbulence can act (cloud age), and the sampling volume/time (atmospheric variability). The model results nicely reproduce the measurements and show that the observed slope can be explained by eddy diffusion profiles as observed from rocket measurements.

Citation: Baumgarten, G., Fiedler, J., and Rapp, M.: On microphysical processes of noctilucent clouds (NLC): observations and modeling of mean and width of the particle size-distribution, Atmos. Chem. Phys. Discuss., 10, 3605-3625, doi:10.5194/acpd-10-3605-2010, 2010.
 
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