Diagnostic Analysis of a Historical Extreme Snow Process in Shandong

Abstract

Based on conventional surface data,reanalysis data from NCEP and TBB data,the comprehensive analysis of snowstorm occurred in Shandong province from 19 to 20 April 2013 was done. The results showas following. It is the main synoptic background to generate the snowstorm that 500 h Pa upper trough,700 h Pa southwest lowlevel jet and the shear line and 850 h Pa low-level northeaster made the backflowsnow. During the snowshorm,snowstorm area physical quantity in the space above the vertical section shows: A relative humidity of 90% or more under high humidity area downloaded and warm moist air along the southern low-level cold climbed,and after reach a certain height,the water vapor condenses snow,and snowstorm fell the center of the area was not located in the strong upward movement,but located in the north side of the center value biggest,between 28°N ~ 40°N has a high energy frontal zone,and along with the increase of latitude leaning to high altitude. Near the ground layer is an obvious convergence field,and distribution of TBB reaction during the snow-storm had meso-microscale system coordination,TBB maximum in between- 45 ~- 40 ℃. Terrain in the extreme blizzard events over a rapid decline in the temperature played a very important role.