Abstract:
Based on 35 Northeast Cold Vortex cases during 2008-2011 and Micaps observation data,the statistic and diagnosis for storm rainfall areas of Northeast Cold Vortex were carried out.The results indicate that most of storm rainfalls occur in the Ⅱand Ⅲ quadrants.There are three high probability areas with storm rainfall in theⅡquadrant.The three areas include the middle part of Jilin province,the borders of China and Korea and Liaodong Peninsula with the maximum probability of 0.6.There is only one high probability area (the North of Hebei province) in the Ⅲ quadrant with probability of 0.5.Furthermore,based on the NCEP/NCAR reanalysis data and the method of composite analysis with the diagnostic values of dynamic conditions and thermal conditions,the distribution of probability of storm rainfall areas are compared.The above analysis shows that there is an obvious transportation of water vapor belt on synoptic scale at low altitudes when the Northeast Cold Vortex is forming.At the same time,a clear wet tongue is formed when water vapor convergence together and the storm rainfall tends to occur on the tip of the wet tongue.Moisture flux divergence,
vector divergence and moisture potential vorticity could be factors for satisfactional forecast of the storm rainfall areas and the areas with high diagnostic value coincide with the high probability areas of storm rainfall,especially in the I,Ⅱ and Ⅲ quadrants of the Northeast Cold Vortex.