Abstract:Under the climatic background of rare precipitation in dry season of Yunnan, the prediction of abnormal drought or flood climate events has been one of the most challenging problems in short term climate prediction. It is of great significance to improve the accuracy of climate prediction by analyzing the climatic causes of abnormal precipitation in dry season. In January, the main period of midwinter, the rainfall in Yunnan is characterized by skewness distribution and the interannual change is very significant. The general circulations between more and less rainfall year in Yunnan in January are quite different. There are four significant impact areas in the 500 hPa field which are closely associated with the rainfall in Yunnan in January. Three of them which are located in the middle or high latitude area respectively correspond to the three centers of Scandinavia Teleconnection Pattern, and the last one lies in low latitude Arab Sea whose geopotential height indicates the intensity of trough in Bengal Bay. When the Scandinavia Teleconnection Pattern is in positive (negative) phase and the geopotential height of Arab Sea is negative (positive), the Yunnan rainfall in January is likely to be less (more). There are two significant impact areas of SST, one is located in the southeast Pacific and the other is in middle west area of North Atlantic. Through affecting the circulations in East Asia and South Asia, the SST has an influence on the precipitation in Yunnan in January. By employing the data of significant impact areas of 500 hPa and SST field, the combined sequences of height field and SST field are synthesized respectively. Both combination sequences have higher correlation coefficients and better corresponding rates of anomaly sign with rainfall in Yunnan in January than those of single impact area data. Based on the combined sequences of 500 hPa and SST field in each year from 1961 to 2017, the scatter graph is drawn. Nearly 80% of the total years is located in the first and third quadrants, where the functions of height field and SST field are consistent with rainfall in Yunnan in January. In this case, the location of the falling zone corresponds well to the anomaly sign of rainfall. The remaining 20% years are located in the second and the fourth quadrants, where the height field and the SST field have opposite functions, and the location of the falling zone corresponds poorly to the anomaly sign of precipitation.