Atmos. Chem. Phys., 13, 11757-11768, 2013
www.atmos-chem-phys.net/13/11757/2013/
doi:10.5194/acp-13-11757-2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
Quantification of waves in lidar observations of noctilucent clouds at scales from seconds to minutes
N. Kaifler, G. Baumgarten, J. Fiedler, and F.-J. Lübken
Leibniz Institute of Atmospheric Physics at the Rostock University, Kühlungsborn, Germany

Abstract. We present small-scale structures and waves observed in noctilucent clouds (NLC) by lidar at an unprecedented temporal resolution of 30 s or less. The measurements were taken with the Rayleigh/Mie/Raman lidar at the ALOMAR observatory in northern Norway (69° N) in the years 2008–2011. We find multiple layer NLC in 7.9% of the time for a brightness threshold of δ β = 12 × 10−10 m−1 sr−1. In comparison to 10 min averaged data, the 30 s dataset shows considerably more structure. For limited periods, quasi-monochromatic waves in NLC altitude variations are common, in accord with ground-based NLC imagery. For the combined dataset, on the other hand, we do not find preferred periods but rather significant periods at all timescales observed (1 min to 1 h). Typical wave amplitudes in the layer vertical displacements are 0.2 km with maximum amplitudes up to 2.3 km. Average spectral slopes of temporal altitude and brightness variations are −2.01 ± 0.25 for centroid altitude, −1.41 ± 0.24 for peak brightness and −1.73 ± 0.25 for integrated brightness. Evaluating a new single-pulse detection system, we observe altitude variations of 70 s period and spectral slopes down to a scale of 10 s. We evaluate the suitability of NLC parameters as tracers for gravity waves.

Citation: Kaifler, N., Baumgarten, G., Fiedler, J., and Lübken, F.-J.: Quantification of waves in lidar observations of noctilucent clouds at scales from seconds to minutes, Atmos. Chem. Phys., 13, 11757-11768, doi:10.5194/acp-13-11757-2013, 2013.
 
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