Multi-scale Integrated Analysis Of Extreme Heavy Rain In Shandong In Spring Of 2009

Based on multiple meteorological data, including NCEP reanalysis data of 1°×1°with 6h intervals, routine-observational data, AWS(Automatic Weather Station) data, Doppler radar data and FY2C meteorological satellite TBB data, the multi-scale characteristics of the extreme heavy rain happened in northwestern and central region of Shandong during 9-10 May 2009 were analyzed and its mechanism was also discussed. The results as follows:1. This extreme heavy rain occurred mainly in northwest of Shandong and north of central regions of Shandong. This rainfall occurred longer duration, but the heavy precipitation period mainly occurred from 20 9th to 3 10th, and from 6 to 10. This extreme heavy rainfall had obvious mesoscale features.2.It was abnormal about the subtropical high which constrained and influenced by the formation of heavy rain in the large-scale system activity. Low-level jet (LLJ), shear line, and cyclone waves were the major systems which caused the extreme heavy rain. The coupling of high-level jet (HLJ) and LLJ made heavy rains maintained and strengthened. Physical quantities from the field analysis showed that:between 700hPa vertical velocity on the horizontal distribution and rain area had a good correspondence. Vertical Helicity analysis of large-scale heavy rain had a certain role in forecasting the direction.3.Meso-scale analysis showed that "09.05" Heavy Rain had a meso-βscale convective systems MPCS. Maximum precipitation Center appeared in the surface wind speed and the flow field convergence and the counter-clockwise area. When the heavy precipitation occurred, a number of positive and negative characteristics of the distribution area of the rainfall areas of divergence were staggered on the surface, and the precipitation areas appeared in the positive and negative convergence and divergence areas of the negative side of the contour-intensive.4,The radar speed map of the adverse wind areas had a good direction on short-term heavy rain. Generally when the adverse wind areas appeared, the value of reflectivity factor was up to 45dBz in echo area, and in three different elevation angles at the same time the areas observed. The speed of low-level jet and rainfall intensity had a certain relationship and the heavy rainfall periods for various high-layer wind speed requirements were different.