Thursday, 9 August 2007
Halls C & D (Cairns Convention Center)
Bow echoes represent one of the unique radar echo forms associated with severe convective organization, often being responsible for the production of long swaths of damaging surface winds, small tornadoes and flash floods. If such structures organize in lines, they often produce squall which, in turn, produce generalized straight line strong winds, named "derecho", an unusual term for the Romanian forecasters who hardly accepted the use of its counterpart, the tornado. This paper presents a catalog of the bow-echoes observed in Romania since the Doppler radar network was installed in 2004. Different characteristics of the bowed structure identified on the reflectivity and radial velocity radar fields , such as the rear inflow notch, bookend vortices, mid-altitude convergence zone and size, are analyzed and connected with the observed severity of the phenomena and with damage. Environment characteristics, such as wind shear and instability, are also presented in order to distinguish between flash flood and severe wind cases associated with bow echoes.
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