Interannual Variability Of Winter Asia-Pacific Oscillation And Its Relationship With The East Asian Climate Anomalies And Pacific SST Anomalies

Usingthe1948-2011NCEP/NCARmonthlyreanalysisdata，the1871-2010monthlymeandata of the twentieth-century reanalysis V2products， the1958-2001monthly ERA-40reanalysis，the1870-2012monthlySSTfromtheHadISSTdatasetand1951-2010accumulatedprecipitation at160meteorological stations of China and empirical orthogonal function (EOF),correlation, and composite analyses， the winter atmospheric tele-connection over theAsian-Pacific region and its association with East Asian winter monsoon and Pacific SST areexamined.Themajorconclusionsareasfollows:(1)The1951-2009NCEP/NCAR monthly reanalysis data，the1951-2009monthly meandataofthetwentieth-centuryreanalysisV2products，the1958-2000monthlyERA-40reanalysisare analyzed，the result shows there is an Asian-Pacific Oscillation (APO) phenomenon inupper-tropospheric temperature disturbance between the Asian-western Pacific region andcentral-eastern Pacific during winter,which is similartothat during summer.When temperaturein the middle and upper layers(700-200hPa)of the troposphere is warmer in the mid and lowerlatitudes ofEastAsia,it is colder in the midand lower latitudes of the central and eastern NorthPacific;viceversa.(2)The winter APO index reflects the variability of the zonal thermal contrast over theAsian-NorthPacificregion.Itischaracterizedbysignificantinterannualvariation，whichshowsa2-7-year varying period by power spectral analysis and a4-year around varying period from1980stoearly2000s，a2-4-yearvaryingperiodfrom1990stoearly2000sbywaveletspectrumanalysis.(3)CorrespondingtoahigherAPOindex，heightdisturbanceinthetroposphereinthemid andhigher latitudes of EastAsiais lower，it is higherinthe midand higher latitudes ofcentraland eastern North Pacific. There is also a seesaw in the lower latitudes between theAsian-westernPacificregionandcentral-easternPacific，butwithareversedphase.Itcanreflectintheuppertroposphere，a long-wavetroughinEastAsiaappearswestwardandhighpressurestretchesnorthwardinthetropicsofEastAsia.(4)Corresponding to a higher APO index，there is a deep anticyclonic anomaly oversouthern China. Meanwhile northeasterly wind anomalies prevail over southern China in thelower troposphere and divergence anomalies of water vapor and downward motion anomaliesalso appear in southern China. Accordingly，the local precipitation decreases. Relationshipsbetween winter APO and atmospheric circulation and precipitation are different from thoseduring summer，which may be the differences between the winter EastAsia mean circulationandthesummerEastAsiameancirculation.(5)Corresponding to a higher APO index，extratropical Pacific SST is warmer，NorthAmerican coast SST is colder，the tropical western Pacific SST is warmer and the tropicalcentralandeasternPacificSSTiscolder.(6)Corresponding to a warmer extratropical Pacific SST，the anomalous features ofextratropical atmospheric circulation are similar to those associated with APO in winter；Correspondingtoa warmertropicalcentralandeasternPacificSST，theanomalousfeaturesofextratropicalatmosphericcirculationaresimilartothoseassociatedwithAPOinwinter，butwitha reversed phase；Corresponding to a warmer tropical western Pacific SST，the anomalousfeatures of extratropical atmospheric circulation are similar to those associated with APO inwinter；Corresponding to a higher TNPM index，the anomalous features of extratropicalatmosphericcirculationaresimilartothoseassociatedwithAPOinwinter.