简介：Previousstudiesemphasizetheimportantroleofa'north-ridgeversussouth-trough'dipole(affectingthelatitudesfrom20°to75°NaroundtheTibetanPlateau)ofanomalousgeopotentialheight(Z)intheearly-2008abnormalcryogenicfreezing-rain-and-snoweventsinthesouthernpartofChina.ThepresentstudyintendstoextracttheleadingsignalfacilitatingthedipolebasedonthenumericaloutputsofafullZ-linearmodelfordiagnosingtheglobalZ.Usingthismodelbuiltonfullprimitiveequationsinspherical-isobariccoordinates,wecanfurthersplittheanomalyofZ-Zfζ-uβ(representingtheZcomponentnotexplicitlyassociatedwiththeCoriolisparameterfanditsmeridionalderivativeβ)into15components.Withthemodel-outputZfζ-uβ(mainlyaccountingforthedipoleunderthegeostrophicbalance)andZ-Zfζ-uβmatricesastheleftandrightsingularvectorsrespectively,amaximumcovarianceanalysis(MCA)isperformedtoextractthesignificant2-4-dayleadingsignalcarriedbytheMCAZ-Zfζ-uβmodeintheupstreamareaofthedipole.Thisleadingsignalismainlyattributedto1)theabnormallystrongwesterliescenteredaroundtheexitregionoftheAtlanticjet-streamand2)thecorrespondinganomalous950-300hPaanticyclonetothesouthoftheabnormallystrongcenterofwesterlies.Theenergyofthepositivewavecenteraroundthisjetexitregionfavorsthedownstreamnorth-ridgewhiletheenergyofthenegativewavecenterassociatedwiththeanomalousanticyclonefavorsthedownstreamsouth-trough.