Observation and analysis of atmospheric rainfall based on the very high frequency radar

Abstract

Very high frequency (VHF) radar can not only get higher resolution atmospheric three-dimensional (3D) wind fields, but also observe complex atmospheric echoes in the rainfall environment. This paper uses Chung-Li VHF Radar with five beams to observe the frontal rainfall and explore the physical process of atmospheric rainfall. The observed results indicate: 1) the height of bright band is at about 3.5 km with the thickness about 0.5 km and is lower about 0.5 km than the zero isotherm observed by the radiosonde. 2) When the strong updraft exists, the rainfall echoes will weaken and the bright band will be indistinct; when the downdraught exists, the rainfall echoes will strengthen and the bright band will be distinct. 3) The thickness of melting layer is about 1 km, the velocity of rainfall particles in the melting layer is smaller than that below it but spectral width is the opposite. The aspect sensitivity calculated from five beams shows that the radar rainfall echoes mainly come from the anisotropic scattering below the melting layer but isotropic scattering in the melting layer.