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Title: Atmospheric Kelvin-Helmholtz b illows captured by the MU radar, lidars and a fish-eye camera
Authors: Luce, Hubert
Kantha, Lakshmi
Yabuki, Masanori  kyouindb  KAKEN_id
Hashiguchi, Hiroyuki  kyouindb  KAKEN_id  orcid https://orcid.org/0000-0001-8033-0955 (unconfirmed)
Author's alias: 橋口, 浩之
Keywords: Kelvin–Helmholtz instability
Turbulence
Kelvin–Helmholtz billows
Wind shear
Kinetic energy dissipation rate
MU radar
Issue Date: 2018
Publisher: Springer Nature
Journal title: Earth and Planeta ry Science
Volume: 70
Thesis number: 162
Abstract: On June 11, 2015, a train of large-amplitude Kelvin–Helmholtz (KH) billows was monitored by the Middle and Upper Atmosphere (MU) radar (Shigaraki MU Observatory, Japan) at the altitude of ~ 6.5 km. Four to five KH billows in formation and decay stages were observed for about 20 min at the height of a strong speed shear (> ~ 30 m s⁻¹km⁻¹), just a few hundred meters above a mid-level cloud base. The turbulent billows had a spacing of about 3.5–4.0 km (3.71 km in average) and an aspect ratio (depth/spacing) of ~ 0.3. The turbulence kinetic energy dissipation rate estimated was of the order of 10–50 mWkg⁻¹, corresponding to moderate turbulence according to ICAO (2010) classification. By chance, an upward-looking fish-eye camera producing pictures once every minute detected smooth protuberances at the cloud base caused by the KH billows so that comparisons of their characteristics could be made for the first time between the radar observations and the pictures. The main characteristics of the KH wave (horizontal wavelength, phase front direction and phase speed) obtained from the analysis of the pictures were fully consistent with those found from radar data. The pictures indicated that the billows were advected by the wind observed at the height of the critical level. They also revealed a very small transverse extent (about twice the horizontal spacing) suggesting that the large-amplitude KH billows were generated by a very localized source. Micro-pulse lidar and Raman–Rayleigh–Mie lidar data also collected during the event permitted us to confirm some of the characteristics of the billows.
Rights: © The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
URI: http://hdl.handle.net/2433/255590
DOI(Published Version): 10.1186/s40623-018-0935-0
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