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Ann. Geophys., 36, 577-586, 2018
https://doi.org/10.5194/angeo-36-577-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Regular paper
03 Apr 2018
High-resolution vertical velocities and their power spectrum observed with the MAARSY radar – Part 1: frequency spectrum
Qiang Li1, Markus Rapp1,a, Gunter Stober2, and Ralph Latteck2 1Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, 82234 Oberpfaffenhofen, Germany
2Leibniz-Institut für Atmosphärenphysik, 18225 Kühlungsborn, Germany
aalso at: Meteorologisches Institut München, Ludwig-Maximilians-Universität München, Munich, Germany
Abstract. The Middle Atmosphere Alomar Radar System (MAARSY) installed at the island of Andøya has been run for continuous probing of atmospheric winds in the upper troposphere and lower stratosphere (UTLS) region. In the current study, we present high-resolution wind measurements during the period between 2010 and 2013 with MAARSY. The spectral analysis applying the Lomb–Scargle periodogram method has been carried out to determine the frequency spectra of vertical wind velocity. From a total of 522 days of observations, the statistics of the spectral slope have been derived and show a dependence on the background wind conditions. It is a general feature that the observed spectra of vertical velocity during active periods (with wind velocity  >  10 m s−1) are much steeper than during quiet periods (with wind velocity  <  10 m s−1). The distribution of spectral slopes is roughly symmetric with a maximum at −5/3 during active periods, whereas a very asymmetric distribution with a maximum at around −1 is observed during quiet periods. The slope profiles along altitudes reveal a significant height dependence for both conditions, i.e., the spectra become shallower with increasing altitudes in the upper troposphere and maintain roughly a constant slope in the lower stratosphere. With both wind conditions considered together the general spectra are obtained and their slopes are compared with the background horizontal winds. The comparisons show that the observed spectra become steeper with increasing wind velocities under quiet conditions, approach a spectral slope of −5/3 at a wind velocity of 10 m s−1 and then roughly maintain this slope (−5/3) for even stronger winds. Our findings show an overall agreement with previous studies; furthermore, they provide a more complete climatology of frequency spectra of vertical wind velocities under different wind conditions.
Citation: Li, Q., Rapp, M., Stober, G., and Latteck, R.: High-resolution vertical velocities and their power spectrum observed with the MAARSY radar – Part 1: frequency spectrum, Ann. Geophys., 36, 577-586, https://doi.org/10.5194/angeo-36-577-2018, 2018.
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Short summary
With the powerful MAARSY radar, we detected 3D wind fields and the vertical winds show a non-Gaussian distribution. We further obtained the frequency spectrum of vertical wind. The distribution of the spectral slopes under different wind conditions is derived and their comparisons with the background horizontal winds show that the spectra become steeper with increasing wind velocities under quiet conditions, approach a slope of −5/3 at 10 m/s and then maintain this slope for even stronger winds.
With the powerful MAARSY radar, we detected 3D wind fields and the vertical winds show a...
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