简介：Particlenumbersizedistribution(PNSD)between10nmand20μmweremeasuredinthePearlRiverDelta(PRD)regioninwinter2011.Theaverageparticlenumberconcentrationofthenucleationmode(10-20nm),Aitkenmode(20-100nm),accumulationmode(100nm-1μm)andcoarsemode(1-20μm)particleswere1552,7470,4012,and19cm-3,respectively.Thevolumeconcentrationofaccumulationmodeparticleswithpeakat300nmaccountedforover70%ofthetotalvolumeconcentration.DiurnalvariationsanddependenciesonmeteorologicalparametersofPNSDwereinvestigated.Thediurnalvariationofnucleationmodeparticleswasmainlyinfluencedbynewparticleformationevents,whilethediurnalvariationofAitkenmodeparticlescorrelatedtothetrafficemissionandthegrowthprocessofnucleationmodeparticles.WhenthePRDregionwascontrolledbyacoldhighpressure,conditionsoflowrelativehumidity,highwindspeedandstrongradiationarefavorablefortheoccurrenceofnewparticleformation(NPF)events.ThefrequencyofoccurrenceofNPFeventswas21.3%duringthewholemeasurementperiod.ParametersdescribingNPFevents,includinggrowthrate(GR)andsourcerateofcondensablevapor(Q),wereslightlylargerthanthoseinpreviousliterature.Thissuggeststhatintensephotochemicalandbiologicalactivitiesmaybethesourceofcondensablevaporforparticlegrowth,evenduringwinterinthePRD.