A 35-GHz polarimetric Doppler millimeter-wavelength radar and its application in observing clouds surrounding typhoon

Clouds play a significant role in the climate change, weather modification, cloud physics and the numerical weather prediction. Millimeter-wavelength radars are one of the most important instruments for researching clouds. In this paper, the first 8mm wave -length cloud radar with Doppler and polarization capabilities in China is introduced, its design, parameters, calibrations and application in measuring clouds surrounding Typhoon are discussed. Due to many advanced technologies such as coherence accumulation and pulsating compression are applied in this radar. Two receivers are used to measure the de-polarization factor. The minimum effective radar reflectivity factor that is measured by the radar at a range of 10 km is about -40dBz.

The cloud radar measurements of reflectivity (Z), Doppler velocity (V), velocity spectrum width (W) and the de-polarization factor (LDR) at vertical incidence are used to analyze the microphysical and dynamical process of the cloud and precipitation surrounding Typhoon in August, 2008. The simultaneously observed reflectivity with S-band weather radar (SA), spaced at 76km is also used to compare the cloud radar observation. The results show that reflectivity observed by cloud radar is consistent with the SA radar as well as echo height and the melting layer, but the millimeter-wavelength radar can reveal more detailed structural information of clouds and weak precipitation than S-band radar. The vertical structure of radar reflectivity and LDR can catch transform of particles from ice to water. The vertical velocity and velocity spectrum width explored the updraft and strong turbuance in stratiform cloud. The cloud radar will provide experience in researching millimeter wavelength radar technology and its application in China.