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Atmos. Chem. Phys. Discuss., 10, 3605-3625, 2010
www.atmos-chem-phys-discuss.net/10/3605/2010/ doi:10.5194/acpd-10-3605-2010 © Author(s) 2010. This work is distributed under the Creative Commons Attribution 3.0 License. |
On microphysical processes of noctilucent clouds (NLC): observations and modeling of mean and width of the particle size-distribution
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.