230 Sub-Rainband Structure and Dynamic Characteristics in the Principle Rainband of Typhoon Hagupit (2008)

Thursday, 31 August 2017
Zurich DEFG (Swissotel Chicago)
Wen-Chau Lee, NCAR, Boulder, CO; and X. Tang and M. M. Bell

The principal rainband in the stationary band complex within tropical cyclones is currently depicted as a solitary and continuous precipitation region. However, the airborne radar observations of the principal rainband in Typhoon Hagupit (2008) reveal multiple sub-rainband structures. This study examines detailed structures of four segments within two sub-rainbands. These segments compose of organized active deep convection and associated stratiform precipitation, and possess many characteristics different from those documented in previous studies. The updraft and reflectivity cores are upright and elevated with two branches of downdraft on both sides. The tangential wind speed shows a clear middle level jet associated with the stratiform precipitation. The middle level jet extends to the lower levels in the segments with stronger convection. The overall structure of the sub-bands is similar and resembles that of the trailing stratiform squall lines in the middle latitude. The unique structures of the sub-bands show positive impacts to the vortex in terms of potential vorticity and angular momentum.
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