简介：

简介：Byanalysisofobservationdata,thispaperdemonstratesthatpollutionparticlescouldreducesurfacewindspeedthroughblockingsolarradiationtotheground.ThecomparationbetweentemperatureatthelowlandmeteorologicalstationXi’anandthatoverthenearbyhighlandstationMt.HuasuggeststhatsurfacesolarradiationatXi’anisreducedduetotheincreasinganthropogenicaerosols.Thereducedsurfaceenergysuppressestheatmosphericinstabilityandconvectiveflows,andthusthedownwardtransferoffasterwindsaloftisreduced.Consequently,windspeedsnearsurfaceareweakened.Thisreductionofsurfacewindsisshownbythesignificantreversetrendsofwindspeedsoverthetwostationsatdifferentelevations.Theaerosols’effectsonwindsarealsomanifestedinthetrendsofradionsondewindspeed.ThedecreasedsurfacewindsinXi’anhavealsoreducedlocalpanevaporation.

简介：

简介：Byusingthedatasetoflightraindaysandlowcloudcoverat51stationsinSouthChina(SC),andthemethodoflinearregressionandcorrelativeanalysis,weanalyzethespatiotemporalcharacteristicsofthelightraindaysandlowcloudcoverincludingannualvariationandlong-termseasonalchange.Theresultsareasfollows:(1)ThetrendsoflightraindaysandlowcloudcoveroverSCareopposite(lightraindaystendedtodecreaseandlowcloudcovertendedtoincreaseinthepast46years).Thevaluedistributedineastishigherthanthatinwest,andcoastalareahigherthaninlandarea.(2)Theregressioncoefficientsoflightraindaysandlowcloudcoverduring1960-2005are4.88d/10yearsand1.14%/10yearsrespectively,whichhadallpassedthe0.001significancelevel.(3)Variationsoflightraindaysarerelativelysmallinspringandsummer,buttheircontributionsarelargerforannualvaluethanthatofautumnandwinter.(4)Therearetworegionswithlargevaluesofaerosolopticaldepth(AOD),whichdistributeincentralandsouthernGuangxiandPearlRiverDelta(PRD)ofGuangdong,andthevalueofAODinPRDisupto0.7.Theaerosolindexdistributedincoastalareaishigherthanintheinlandarea,whichissimilartothelightraindaysandlowcloudcoveroverSC.AerosolindexesinSCkeptincreasingwithfluctuationduringthepast27years.TheGDPofthethreeprovincesinSCincreasedobviouslyduringthepast28years,especiallyinGuangdong,whichexhibitedthatthereissimultaneouscorrelationbetweenlightraindayswiththevariablesoflowcloudcoverandreleaseofaerosolsoverSCduring1960to2005.

简介：Basedonobservationsofurbanmassconcentrationoffineparticulatemattersmallerthan2.5μmindiameter(PM_(2.5)),groundmeteorologicaldata,verticalmeasurementsofwinds,temperature,andrelativehumidity(RH),andECMWFreanalysisdata,themajorchangesintheverticalstructuresofmeteorologicalfactorsintheboundarylayer(BL)duringtheheavyaerosolpollutionepisodes(HPEs)thatoccurredinwinter2016intheurbanBeijingareawereanalyzed.TheHPEsaredividedintotwostages:thetransportofpollutantsunderprevailingsoutherlywinds,knownasthetransportstage(TS),andthePM_(2.5)explosivegrowthandpollutionaccumulationperiodcharacterizedbyatemperatureinversionwithlowwindsandhighRHinthelowerBL,knownasthecumulativestage(CS).DuringtheTS,asurfacehighliessouthofBeijing,andpollutantsaretransportednorthwards.DuringtheCS,astableBLformsandischaracterizedbyweakwinds,temperatureinversion,andmoistureaccumulation.Stableatmosphericstratificationfeaturedwithlight/calmwindsandaccumulatedmoisture(RH>80%)below250matthebeginningoftheCSiscloselyassociatedwiththeinversion,whichisstrengthenedbytheconsiderabledecreaseinnear-surfaceairtemperatureduetotheinteractionbetweenaerosolsandradiationaftertheaerosolpollutionoccurs.AsignificantincreaseinthePLAM(ParameterLinkingAerosolPollutionandMeteorologicalElements)indexisfound,whichislinearlyrelatedtoPMmasschange.Duringthefirst10hoftheCS,themorestableBLcontributesapproximately84%oftheexplosivegrowthofPM_(2.5)mass.Additionalaccumulatednear-surfacemoisturecausedbythegroundtemperaturedecrease,weakturbulentdiffusion,lowBLheight,andinhibitedverticalmixingofwatervaporisconducivetothesecondaryaerosolformationthroughchemicalreactions,includingliquidphaseandheterogeneousreactions,whichfurtherincreasesthePM_(2.5)concentrationlevels.Thecontributionofthesereactionmechanisms