Distribution of Doppler Radar Radial Velocity of the Returnflow Events over North China
Using Doppler radar data, the four return flow events were analyzed. T he results are as follows: (1) PPI showed a large range symmetrical flaky reflec tivity with flat top. And 0℃ bright belt occurred in higher beams. (2) On VPPI, “0” line crossed through the radar station and showed a structure like “S”. The wind veered with height from NE to W, until SW with warm advection in lower layer. Acompanying with the cold advection around the top of boundary, efficienc y of precipitation became strong. (3) The wind direction were discontinuous in the vertical direction, NE in the low layer and SW in the middle. The vertical sh ear was observed on VAD.〖JP〗 The start and end time of precipitation was close ly related to the wind direction, including boundary layer NE wind and middle layer SW wind.