The Characteristic Of Winter Monthly North Pacific Oscillation And Its Association With Precipation Anomaly In China And Pacific Sea Surface Temperature Anomaly

By using the ERA-interim reanalyzed gridding data provided by European Centre for Medium-Range Weather Forecasts (ECMWF), the monthly mean precipitation data of 160 stations in China provided by the National Climate Center and monthly SST (HadiSST) from the Met Office Hadley Centre, with climatological statistics analysis and variability diagnosis method of Empirical Orthogonal Function (EOF), linear correlation analysis, linear regression analysis, composite analysis and Morlet wavelet analysis, the interannual variability of winter monthly North Pacific Oscillation (NPO) are studied. On this basis, the relationships of winter monthly NPO and precipitation over the simultaneous and later period in China are analyzed. Besides, we also discuss the relationship of winter monthly NPO and North Pacific Sea Surface Temperature Anomaly (SSTA). The result show that:(1) Winter monthly NPO has a significant inter-annual variation with 2-4a periods. Besides, February NPO also has interdecadal variation of quasi-10a.The correlations of inter-annual variation of winter monthly NPO indices are weak. The correlation coefficients between the NPO index in December and NPO index in January was 0.04, while correlation coefficients between NPO index in January and NPO index in February only was 0.12 during 1979-2012, without passing the confidence levels. There are only eleven years when winter monthly NPO is in the same phase in 34 years data, accounting for 32%.(2) There were significantly positive correlation between the variations of NPO and the simultaneous precipitation of Huanghuai basin in December and January. In addition, NPO in December was also negatively correlated with the simultaneous precipitation anomaly in northeast China. But the variation of NPO in February relates positively with the simultaneous precipitation of eastern Tibetan plateau in China. The precipitation increases about 60%(40%) of its climatology as the NPO index increases one standard deviation in January (December). While the NPO index increases one standard deviation in February, the precipitation of eastern Tibetan plateau in China will increase about 20%.(3) The relationship of winter monthly NPO and simultaneous sea surface temperature anomaly over the North Pacific is closely associated. When the NPO index is positive, there is a "-+-" triple pole SSTA in the north Pacific. There is significantly positive correlation between the variation of NPO in December and the simultaneous SSTA in the eastern and central tropical Pacific, but it is not obvious in January and February.