Relationship Between Non-uniformity Of Precipitation Distribution In Northeast China And General Atmospheric Circulation In Early Winter

In this paper,using the precipitation data of 105 routine meteorological stations in Northeast,35 circulation indices and NCEP/NCAR monthly mean reanalysis data from 1959 to 2016,the variations of PCD and its relationships to circulation situation were analylized with the aid of REOF,linear trend,wavelet analysis,SVD,synthesis analysis,etc.The results were as followed:1.In the south of 48°N of Northeast precipitation is tended to concentrate from east to west,and in the north of 48°N,precipitation in the south is more concentrated than it in the north.On interannual change,the overall performance is a declining trend,and this decline is obvious.Interdecadal changes indicate,Precipitation concentration degree was positive anomalies in the 60 s and 80 s,and the precipitation was more concentrated.After 2000,there was a significant negative anomaly and the precipitation was less concentrated.Cycle analysis shows that there is a significant period of 3 to 4 years oscillation of PCD in Northeast China after 2000.2.Through the REOF method and the consistency test,the PCD in the northeast is divided into two regions: ?*(Southeast)and ?*(Northwest).The correlation between PCD and 35 circulation index fields in ?* and ?* regions was analyzed by SVD method.The results showed that: PCD in ?* region was significantly negatively correlated with the East Asian trough strength index and subtropical high,and was positively correlated with Asia's polar vortex area index.Significant positive correlation;PCD in region ?* was positively correlated with the intensity index of polar vortex in Asia,and negatively correlated with the height of paraplegia.3.Through correlation analysis and synthesis analysis: The circulation field in the middle and high latitudes has a greater influence on the PCD in the ?* zone.In the sea level pressure field,the pressure in the Asian continent is stronger(weaker),the pressure in the Aleutian is stronger(weaker),and the pressure in Greenland is stronger(weaker).I * The more concentrated precipitation(not concentrated)during the year.In the 500 h Pa circulation field,the larger troughs in East Asia are stronger(weaker),and the lower(higher)sea level pressures on the African continent and the eastern and western coasts are,and the more concentrated(not concentrated)precipitation is in the ?* region during the year.Low latitudes have a greater impact on PCD in ?*,and negative correlations on sea level pressure field and 500 h Pa height field.4.The large-area strength index calculated by selecting the high correlation region has the best predictive effect on the PCD in the ?* region.The East Pacific Subtropical High Area Index provided by the National Climate Center has the best predictive effect on PCD in ?* District.5.According to the rule of the seasonal development of the circulation of PCD in Northeast China,in the ?* region,the high pressure in the Asian continent,the high pressure in Greenland,and the large trough in East Asia from winter to spring are all stronger than the PCD anomalies in the year of abnormally large PCD values in the ?* region.In region ?*,from winter to spring to summer,the difference in the intensity of the subtropical high in the PCD anomaly year and the PCD anomaly year is always significant.It shows that the above-mentioned circulation systems have continuous consistency from east to spring and summer intensity evolution,and the high pressure in Asia,high pressure in Greenland,and the stronger(weaker)large trough in East Asia,the larger(smaller)the PCD in ?* zone.The uneven distribution of precipitation within the year in the ?* area is closely related to the subtropical high,affected by the subtropical high intensity,and the subtropical high is stronger(weaker),the larger(smaller)the area,the smaller the PCD in the area II(larger).