Proceedings with Extended Abstracts (single PDF file) - Radio ...

Observations of Typhoon 9426 (Orchid) with the MU radar:Meso--scale kinematic structure and meso- -scale precipitating cloudsYoshiaki Shibagaki 1 , Manabu D. Yamanaka 2 , Minori Kita-Fukase 3 , Hiroyuki Hashiguchi 4 ,Yasuyuki Maekawa 1 and Shoichiro Fukao 41: Osaka Electro-Communication University, Osaka 572-8530, Japan2: Graduate School of Science and Technology Kobe University Kobe 657-8501, Japan3: Weather News International company, Chiba 261-0023, Japan4: Radio Science Center for Space and Atmosphere, Kyoto University, Kyoto 611-0011, Japan1. IntroductionIn general, a main precipitation system of a tropical cycloneis of meso-scale, and itconsisted of meso--scale precipitation systems (or organized precipitation systems), such asprincipal band, secondary band, connecting band, and an eyewall. Kinematic structures of theprecipitation systems in various scales have been revealed in many observational studies.Since studies covering simultaneously the precipitation systems of different scale were few,however, a general structure of tropical cyclones has not been well understood.On 29-30 September 1994, we successfully observed Typhoon 9426 (Orchid) by the MU(middle and upper atmosphere) radar of the VHF band at Shigaraki, Shiga, Japan (136.10E, 34.85N), the center of which almost passed over the radar site (Fig. 1). This is the firstobservation to continuously obtain information up to the lower stratosphere including theinner core region. The typhoon was also observed by an UHF-band radar called the BoundaryLayer Radar (BLR) at a distance of 65 km southwest from the MU site. The purpose of thepresent paper is to demonstrate the meso--scale wind and precipitation fields, and to clarifymeso-and --scale features of rainbands and the inner core in the typhoon.2. Meso--scale kinematic structure of the typhoonIn front of the typhoon (Fig. 1), the meso--scale wind field is characterized by the low-levelcyclonic wind with the maximum and outflow regions tilted outward with height. The tiltedoutflow regions may be interpreted as internal gravity waves, proposed as a mechanism of theoutward-propagating rainband in previous studies. The continuous strong updraft occurswithin the stationary precipitating cloud through the orographic effect of the higher mountainregion. Meso--scale updrafts appear within the inner cloud and band-shaped cloud at upperlevel. The upper-level clouds seem to contribute to the formation and maintenance of thestratiform precipitation by the seeder-feeder mechanism. In the vicinity of the typhoon center,the tangential wind has the vertical spiral structure for the center, considered as a result fromthe deformation of the center of the decaying typhoon. In the rear of the typhoon without258