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Abstract
Derechos occur frequently in Europe and the United States, but reports of derechos in China are scarce.
In this paper, radar, satellite, and surface observation data are used to analyze a derecho event in South
China on 17 April 2011. A derecho-producing mesoscale convective system formed in an environment with
medium convective available energy, strong vertical wind shear, and a dry layer in the middle troposphere,
and progressed southward in tandem with a front and a surface wind convergence line. The windstorm can
be divided into two stages according to differences in the characteristics of the radar echo and the causes of
the gale. One stage was a supercell stage, in which the sinking rear inflow of a high-precipitation supercell
with a bow-shaped radar echo induced a Fujita F0 class gale. The other stage was a non-supercell stage
(the echo was sequentially kidney-shaped, foot-shaped, and an ordinary single cell), in which downbursts
induced a gale in Fujita F1 class.
This derecho event had many similarities with derechos observed in western countries. For example, the
windstorm was perpendicular to the mean flow, the gale was located in the bulging portion of the bow echo,
and the derecho moved southward along with the surface front. Some differences were observed as well.
The synoptic-scale forcing was weak in the absence of an advancing high-amplitude midlevel trough and
an accompanying strong surface cyclone; however, the vertical wind shear was very strong, a characteristic
typical of derechos associated with strong synoptic-scale forcing. Extremely high values of convective availa-
ble potential energy and downdraft convective available potential energy have previously been considered
necessary to the formation of weak-forcing archetype and hybrid derechos; however, these values were much
less than 2000 J during this derecho event.
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Citation
XIA Rudi, WANG Donghai, SUN Jianhua, WANG Gaili, XIA Guancong. 2012: An Observational Analysis of a Derecho in South China. Journal of Meteorological Research, 26(6): 773-787.
XIA Rudi, WANG Donghai, SUN Jianhua, WANG Gaili, XIA Guancong. 2012: An Observational Analysis of a Derecho in South China. Journal of Meteorological Research, 26(6): 773-787.
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XIA Rudi, WANG Donghai, SUN Jianhua, WANG Gaili, XIA Guancong. 2012: An Observational Analysis of a Derecho in South China. Journal of Meteorological Research, 26(6): 773-787.
XIA Rudi, WANG Donghai, SUN Jianhua, WANG Gaili, XIA Guancong. 2012: An Observational Analysis of a Derecho in South China. Journal of Meteorological Research, 26(6): 773-787.
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