Relationship Between Winter Snow Cover Days in Northeast China and Rainfall near the Yangtze River Basin in the Following Summer

Based on observed snow and precipitation data and NCEP/NCAR reanalysis data, the relationship between the number of winter snow cover days in Northeast China and the following summer's rainfall in the northern part of southern China is analyzed and the possible underlying mechanisms are discussed. The results indicate that a negative relationship is significant throughout the study period, especially more obvious after the 1980s. The pre-winter circulation patterns in years with more snow cover days and less summer rainfall in the south bank of the Yangtze River are almost the same. In years with more snow cover days, lower temperatures at the lower level over Northeast China are found in winter and spring. The winter monsoon is weaker and retreats later in these years than in those with fewer snow cover days. In spring of years with more snow cover days, anomalous cyclonic circulation is observed over Northeast China, and anomalous northerly wind is found in eastern China. In summer of these years, anomalous northeasterly wind at the lower level is found from the area south of the Yangtze River to the East China Sea and Yellow Sea; and with less southwesterly water vapor transport, the rainfall in the area south of the Yangtze River is less than normal, and the opposite patterns are true in years with fewer snow cover days. In recent years, the stable relationship between winter snow cover in Northeast China and summer rainfall in the Yangtze River basin can be used for summer rainfall prediction. The results are of great importance to short-term climate prediction for summer rainfall.