Analysis on a Meso-γ Scale of Local Short-Time Heavy Rainstorm
A local short-time heavy rainstorm, which takes place in the north-west of Shijiazhuang on 14 August 2008, is analyzed by means of Doppler radar, ground automatic station data and 4DVAR wind retrieval method. The obtained conclusions are as follows: (1) In general, the radar reflectivity exceed 60 dBz and convergence zone exist in radial velocity PPI when short-time heavy rainstorm occur. (2) It is possible that the short-time heavy rainstorm is forecasted more than 18 min in advance based on the radar products such as ET and VII. (3) 4DVAR method can clearly reveal the low-level wind field structure of rainstorm: A cyclonic vortex is first generated in the region of heavy rain, and then the southwest airflow in front of the vortex arouses severe convection echo which maintain stability because of the convergence always existing, and lead the local heavy rainstorm. Whereby, the meso-γ scale or small scale systems can be revealed by 4DVAR wind field retrieval, which can play an important role in forecasting the drop zone of heavy rainstorm, tracking the generation and evolution of meso-γ scale vortex, and understanding the mechanism of the local short-time rainstorm clearly.
Local heavy rainstormRadar products4DVAR wind retrieval
NETL
NSTL
万方数据
维普
