During the Intensive Observation Period (IOP) 9c of the Convective and Orographically-induced Precipitation Study (COPS) on 20 July 2007 a frontal zone passed over the COPS region, with a Mesoscale Convective System (MCS) imbedded in it. The Raman lidar system BASIL which was deployed in Achern (Supersite R, Lat: 48.64 ° N, Long: 8.06 0 E, Elev.: 140 m) in the frame of the COPS was operated continuously during this day. The lidar data determined the lowering of the anvil clouds, which is a signature for the approaching thunderstorm. During the time frame 10:46-11:37 UTC cloud deck is present around 2 km, which represents a mid-level outflow from the thunderstorm. Wind profiler data reveal that the wind flow at higher levels is opposite with respect to low level winds. The effect of this is to moisten that level and precipitate (mostly virga) to recycle back. Waves like structures were also seen in the data just prior to the arrival of the thunderstorm, which are due to shear between inflow or outflow regions. Thus, two primary processes stand out: the elevated outflow region above the BL (2-3.5 km) and the presence of associated shear, which helped in modifying the environment. Measurements in terms of particle backscatter and water vapour mixing ratio are discussed to illustrate the above phenomena.

STUDY OF AN MCS USING RAMAN LIDAR IN THE FRAME OF THECONVECTIVE AND OROGRAPHICALLY-INDUCED PRECIPITATION STUDY

DI GIROLAMO, Paolo;
2009-01-01

Abstract

During the Intensive Observation Period (IOP) 9c of the Convective and Orographically-induced Precipitation Study (COPS) on 20 July 2007 a frontal zone passed over the COPS region, with a Mesoscale Convective System (MCS) imbedded in it. The Raman lidar system BASIL which was deployed in Achern (Supersite R, Lat: 48.64 ° N, Long: 8.06 0 E, Elev.: 140 m) in the frame of the COPS was operated continuously during this day. The lidar data determined the lowering of the anvil clouds, which is a signature for the approaching thunderstorm. During the time frame 10:46-11:37 UTC cloud deck is present around 2 km, which represents a mid-level outflow from the thunderstorm. Wind profiler data reveal that the wind flow at higher levels is opposite with respect to low level winds. The effect of this is to moisten that level and precipitate (mostly virga) to recycle back. Waves like structures were also seen in the data just prior to the arrival of the thunderstorm, which are due to shear between inflow or outflow regions. Thus, two primary processes stand out: the elevated outflow region above the BL (2-3.5 km) and the presence of associated shear, which helped in modifying the environment. Measurements in terms of particle backscatter and water vapour mixing ratio are discussed to illustrate the above phenomena.
2009
9783881484404
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11563/33050
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