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- ItemSimultaneous observations of a Mesospheric Inversion Layer and turbulence during the ECOMA-2010 rocket campaign(Göttingen : Copernicus, 2013) Szewczyk, A.; Strelnikov, B.; Rapp, M.; Strelnikova, I.; Baumgarten, G.; Kaifler, N.; Dunker, T.; Hoppe, U.-P.From 19 November to 19 December 2010 the fourth and final ECOMA rocket campaign was conducted at Andøya Rocket Range (69 N, 16 E) in northern Norway. We present and discuss measurement results obtained during the last rocket launch labelled ECOMA09 when simultaneous and true common volume in situ measurements of temperature and turbulence supported by ground-based lidar observations reveal two Mesospheric Inversion Layers (MIL) at heights between 71 and 73 km and between 86 and 89 km. Strong turbulence was measured in the region of the upper inversion layer, with the turbulent energy dissipation rates maximising at 2 W kg-1. This upper MIL was observed by the ALOMAR Weber Na lidar over the period of several hours. The spatial extension of this MIL as observed by the MLS instrument onboard AURA satellite was found to be more than two thousand kilometres. Our analysis suggests that both observed MILs could possibly have been produced by neutral air turbulence.
- ItemLITOS - A new balloon-borne instrument for fine-scale turbulence soundings in the stratosphere(Göttingen : Copernicus, 2011) Theuerkauf, A.; Gerding, M.; Lübken, F.-J.We have developed a new compact balloon payload called LITOS (Leibniz-Institute Turbulence Observations in the Stratosphere) for high resolution wind turbulence soundings in the stratosphere up to 35 km altitude. The wind measurements are performed using a constant temperature anemometer (CTA) with a vertical resolution of ∼2.5 mm, i.e. 2 kHz sampling rate at 5 m/s ascent speed. Thereby, for the first time, it is possible to study the entire turbulence spectrum down to the viscous subrange in the stratosphere. Including telemetry, housekeeping, batteries and recovery unit, the payload weighs less than 5 kg and can be launched from any radiosonde station. Since autumn 2007, LITOS has been successfully launched several times from the Leibniz-Institute of Atmospheric Physics (IAP) in Kühlungsborn, Germany (54° N, 12° E). Two additional soundings were carried out in 2008 and 2009 in Kiruna, Sweden (67° N, 21° E) as part of the BEXUS program (Balloon-borne EXperiments for University Students). We describe here the basic principle of CTA measurements and prove the validity of this method in the stratosphere. A first case study allows a clear distinction between non-turbulent regions and a turbulent layer with a thickness of some tens of meters. Since our measurements cover the transition between the inertial and viscous subrange, energy dissipation rates can be calculated with high reliability.
- ItemOn microphysical processes of noctilucent clouds (NLC): Observations and modeling of mean and width of the particle size-distribution(Göttingen : Copernicus, 2010) Baumgarten, G.; Fiedler, J.; Rapp, M.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 mean particle sizes up to 40 nm. For the vertically resolved particle properties (Δz = Combining double low line 0.15 km) the slope is comparable and about 0.39±0.03. For particles larger than 40 nm the distribution width becomes nearly independent of particle size and even decreases in the lower part of the layer. 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. © 2010 Author(s).