关键词: 品质, 品质

Abstract: Blizzard process is one of the important disastrous weather in autumn and winter in Shandong Province, to strengthen the analysis of the disastrous weather forecast, improve the ability and level, the author based on the conventional observational data, the circulation situation and mesoscale and dynamic and thermodynamic characteristics of heavy snowstorm of return-flow events in Shandong Province on November since 2000 were analyzed. The results showed that: these heavy snowstorm of return-flow events had phase transformation (rain and snow), temperatures below 925 hPa was a very useful index for precipitation phase. The conceptual model of these events were the trough of 500 hPa and 700 hPa in the Hetao Area or east, the shear line of 850 hPa from the southwest to the Shandong, the high pressure from northwest to southeast of ground, directly affect system were trough, shear line and low-level jet. The thick layers of atmospheric humidity to middle troposphere or higher, the inversion layer were important characteristics of these events. The characteristics had strong convergence in the lower vapor flux divergence field, low zone of θse extended to the hinterland of the central plains, convective instability in the atmosphere of the top, alternately convergence and divergence of divergence from up to down, ascending motion of vertical velocity field from the surface to the tropopause.