Study on the 3D Structure of the Severe Heavy Rainfall in Chuzhou area during 1~2 August 2008 with Dual-Doppler Radar

Due to the effect of the low-pressure system of Fung-Wong and the cold air, it produced a heavy precipitation in the east region of Anhui province in China, up to 429mm rainfall in Chuzhou and 414mm in Quanjiao from 0800 on 1 August to 0800 on 2 August 2008. It is a local, sudden and short time heavy rain. The three dimensional wind fields were retrieved by the volume scan data of the dual-Doppler radar located in Nanjing and Maanshan cities. The evolution of the 3D wind fields and the formation mechanism of the sudden heavy rainfall were investigated. It is a convective cloud precipitation based on the radar echo analyses. The meso-β-scale convective system (MβCS) and the meso-γ-scale system located on the MβCS played an important role on this heavy rainfall. The meso-β-scale convective cloud has high precipitation efficiency. The dual-Doppler retrieved wind reveals that the heavy rainfall was caused by the meso-β-scale shear line and meso-γ-scale convergence lines at the low and the medium levels. The shear line triggered and maintained the heavy rainfall. There were strong convergence and vorticity at the low and medium levels of the MβCS. The shear line spread from west to east, and the heavy rainfall center moved from the west to east at the same time. When the shear line at the low and medium levels began to weak, the precipitation began to weak too. The intensity of the precipitation weakened remarkably when the shear line dissipated. The 3D kinematic conceptual structure model of this heavy rainfall case is given too.

Keywords: Dual-Doppler radar; Wind retrieval; Heavy rainfall; Mesoscale structure