Interdecadal Variations of Annual Precipitation in Northeast China and Its Neighborhood during Past 50 Years

The climatic inter-decadal variations in Northeast China are analyzed and studied by using the observational data from 195 stations in Northeast China and 6 stations in Mongolia with EOF and REOF analyses and the means of separated time interval linear fitting.It is found that:(1) In the recent 50 years the annual precipitation performed the course of more-less-more in Northeast China and more-less in North China,showing that Northeast China has been changing from dry to humid while Northern China has been changing from humid to dry since the 1980s.(2) There are three precipitation patterns in the studied region: the consistent pattern in all of the sub-regions,the opposite pattern in the north and the south and the pattern with consistency in the north and south but opposite in the middle.(3) The precipitation is gradually decreasing,resulting in a worse drought of the south,but it is slightly increasing in the northeast part in the last 30 years.(4) The precipitation in most sub-regions experienced an abrupt change in the middle of the 1970s and early in the 1980s,but the changing direction,scope and time were different.