ドップラーライダーで検出したDust devilの特徴(渦・回転+大気(2),一般講演)

概要

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Using a three-dimensional scanning coherent Doppler lidar (3D-CDL), we conducted atmospheric boundary layer (ABL) observation in an urban area, Sapporo, Japan, from April of 2005 to June of 2007. During this period, we succeeded in detecting more than one hundred "invisible dust devils" in 7 days, which is the first detection of such a dust devil in urban areas. They appeared only in the daytime under relatively weak wind conditions with superadiabatic lapse rate near the ground surface, when the "fish net" pattern of wind fields in ABL scale was also detected by the 3D-CDL. Characteristics of relatively strong dust devils having vertical vorticity of more than 0.1s^<-1> are summarized as follows: the diameter ranged from 30m to 120m, the maximum vorticity was 0.26s^<-1>, and the number ratio of cyclonic to anti-cyclonic rotation was 2:1 on the average. Vertical vortices were also detected along sea-breeze fronts. This fact suggests that horizontal shear associated with the sea-breeze front would play an important role in their formation.
日本流体力学会の論文
2009-09-02