Atmos. Chem. Phys. Discuss., 13, 7397-7429, 2013
© Author(s) 2013. This work is distributed
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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 by lidar at an unprecedented temporal resolution of 30 s and 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 data set 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 significant periods at all time scales 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 −1.84 ± 0.31 for centroid altitude, −1.28 ± 0.29 for peak brightness and −1.62 ± 0.28 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. Discuss., 13, 7397-7429, doi:10.5194/acpd-13-7397-2013, 2013.
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