Typhoon 9707 observations with the MU radar and L-band boundary layer radar

Typhoon 9707 (Opal) was observed with the VHF-band Middle and Upper atmosph ere (MU) radar, an L-band boundary layer radar (BLR), and a vertical-pointi ng C-band meteorological radar at the Shigaraki MU Observatory in Shiga pre fecture, Japan on 20 June 1997. The typhoon center passed about 80km southe ast from the radar site. Mesoscale precipitating clouds developed due to wa rm-moist airmass transport from the typhoon, and passed over the MU radar s ite with easterly or southeasterly winds. We primarily present the wind beh avior including the vertical component which a conventional meteorological Doppler radar cannot directly observe, and discuss the relationship between the wind behavior of the typhoon and the precipitating system. To investig ate the dynamic structure of the typhoon, the observed wind was divided int o radial and tangential wind components under the assumption that the typho on had an axi-symmetric. structure. Altitude range of outflow ascended from 1-3 km to 2-10 km with increasing distance (within 80-260 km range) from t he typhoon center, and inflow was observed above and below the outflow. Out flow and inflow were associated with updraft and downdraft, respectively. I n the tangential wind, the maximum speed of counterclockwise winds was conf irmed at 1-2km altitudes. Based on the vertical velocity and the reflectivi ty obtained with the MU radar and the C-band meteorological radar, respecti vely, precipitating clouds, accompanied by the wind behavior of the typhoon , were classified into stratiform. and convective precipitating clouds. In the stratiform precipitating clouds, a vertical shear of radial wind and th e maximum speed of counterclockwise wind were observed. There was a strong reflectivity layer called a 'bright band' around the 4.2 km altitude. We co nfirmed strong updrafts and downdrafts below and above it, respectively, an d the existence of a relatively dry layer around the bright band level from radiosonde soundings. In the convective precipitating clouds, the regions of strong and weak reflectivities were well associated with those of updraf t and downdraft, respectively.