简介：MeteoroidsenteringtheEarth'satmospherecancreatemeteortrailirregularityseriouslydisturbingthebackgroundionosphere.AlthoughnumerousobservationsofmeteortrailirregularitieswereperformedwithVHF/UHFcoherentscatterradarsinthepast,nosimultaneousradarandopticalinstrumentswereemployedtoinvestigatethecharacteristicsofmeteortrailirregularityanditscorrespondingmeteoroid.ByinstallingmultiplevideocamerasneartheSanyaVHFradarsite,anobservationalcampaignwasconductedduringtheperiodfromNovember2016toFebruary2017.Atotalof242opticalmeteorswithsimultaneousnon-specularechoesbackscatteredfromtheplasmairregularitiesgeneratedinthecorrespondingmeteortrailswereidentified.Agoodagreementbetweentheangularpositionsofnon-specularechoesderivedfromtheSanyaradarinterferometerandthoseofopticalmeteorswasfound,validatingthattheradarsystemphaseoffsetshavebeenproperlycalibrated.TheresultsalsoverifytheinterferometrycapabilityofSanyaradarformeteortrailirregularityobservation.Thenon-specularechoeswithsimultaneousopticalmeteorsweredetectedatmagneticaspectanglesgreaterthan~78°.Basedonthemeteorvisualmagnitudeestimatedfromtheopticaldata,itwasfoundthattheradarnonspecularechoescorrespondingtobrightermeteorssurvivedforlongerduration.Thiscouldprovideobservationalevidenceforthesignificanceofmeteoroidmassonthedurationofmeteortrailirregularity.Ontheotherhand,thesimultaneousradarandvideocommon-volumeobservationsshowedthatthereweresomecaseswithopticalmeteorsbutwithoutradarnon-specularechoes.Onepossibilitycouldbethatsomeoftheopticalmeteorsappearedatextremelylowaltitudeswheremeteortrailirregularitiesrarelyoccur.

简介：Observationsofaquasi-90-dayoscillationinthemesosphereandlowerthermosphere(MLT)regionfromApril2011toDecember2014arepresentedinthisstudy.Thereisclearevidenceofaquasi-90-dayoscillationintemperaturesobtainedfromtheKunmingmeteorradar(25.6°N,103.8°E)andSoundingoftheAtmosphereusingBroadbandEmissionRadiometry(SABER),aswellasinwindobservedbytheKunmingmeteorradar.Thequasi-90-dayoscillationappearstobeaprominentfeatureinthetemperaturesandmeridionalwindtidesandpresentsquiteregularcyclesthatoccurapproximatelytwiceperyear.Theamplitudesandphasesofthequasi-90-dayoscillationintheSABERtemperatureshowafeaturesimilartothatofupward-propagateddiurnaltides,whichhaveaverticalwavelengthof~20kmabove70km.Intheloweratmosphere,asimilar90-dayvariabilityispresentedinthesurfacelatentheatfluxandcorrelateswiththetemperatureintheMLTregion.Similartothequasi-90-dayoscillationintemperature,a90-dayvariabilityofozone(O3)isalsopresentintheMLTregionandisconsideredtobedrivenbyasimilarvariabilityintheupwardly-propagateddiurnaltidesgeneratedintheloweratmosphere.Moreover,the90-dayvariabilityintheabsorptionofultraviolet(UV)radiationbydaytimeO3intheMLTregionisaninsitusourceofthequasi-90-dayoscillationintheMLTtemperature.