Premium
Kelvin‐Helmholtz billows generated at a cirrus cloud base within a tropopause fold/upper‐level frontal system
Author(s) -
Luce Hubert,
Nishi Noriyuki,
Caccia JeanLuc,
Fukao Shoichiro,
Yamamoto Masayuki K.,
Mega Tomoaki,
Hashiguchi Hiroyuki,
Tajiri Takuya,
Nakazato Masahisa
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2011gl050120
Subject(s) - tropopause , cloud base , atmospheric sciences , geology , ice cloud , cirrus , jet stream , storm , wind shear , radiative transfer , cold front , climatology , environmental science , jet (fluid) , physics , stratosphere , wind speed , mechanics , cloud computing , oceanography , quantum mechanics , computer science , operating system
For the first time, trains of Kelvin‐Helmholtz billows of ∼100–1500 m in depth persisting for about 60 hours at the south extremity of a tropopause fold are reported. The structures were monitored by the VHF Middle and Upper atmosphere radar (Shigaraki, 34.85°N, 136.10°E) in November 2008 at the base of cirriform clouds simultaneously detected by a Ka‐band radar. ECWMF reanalysis data indicate that these clouds were advected and spread out by the sub‐tropical jet‐stream from a tropical storm area while dry and cold air penetrated beneath the upper‐level front. The KH billows were likely continuously generated over horizontal extent of several thousand kilometers for several days without evidence of breaking into three‐dimensional turbulence. Rather than radiative effects, our observations suggest that cooling by sublimation of ice particles precipitating in the frontal layer contributed to their generation. These results should motivate further studies on the interaction between clouds and shear instabilities.