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Large-scaleWaveStructuresinO/N2TheNeedforGOLD/ICON/COSMIC-2DataSynthesis

JensOberheideClemsonUniversity

Geospace ICON/GOLD/COSMICWorkshop,Boulder,September27-28,2016

ScienceObjective

• Understandhowthermospheric compositionrespondstoPW’sandupwardpropagatingtides&theconsequencesfortheionosphere→ Measureforlarge-scalewavedynamicsandthethermosphere’s

responsetotroposphericandstratosphericvariability

→ Loweratmosphere/ionospherecouplingthroughcompositionchanges;inadditiontoE-regiondynamoandion/dynamicscoupling

Challenge

• Howtointerpretobservedlarge-scalewavestructuresinO/N2?→ “true”dynamicalsignalvs.ionospheric contamination

→ Consequencesfordataassimilation

→ SynthesisofGOLD,ICON,andCOSMICdata&empiricalmodeling

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TidalDynamicsintheThermosphere

Nonmigrating diurnalandsemidiurnaltidesfromTIMED-basedCTMTmodelFootprintoftroposphericandstratosphericvariability(migratingtidesomitted)

Equatorialnonmigrating tidesat12hLST

Oberheideetal.,JGR2011(2011JA016784)

TidalDynamicsintheThermosphereDiurnal Semidiurnal

Thermospheric verticalwindspectrafromCTMTmodel(migratingtidesomitted)

NoDW5(dissipated),DE3andSE2strong

E-regiondynamozonalwindspectrafromTIDI(migratingtidesomitted)

DW5veryweak,DE3,SE2,SPW4strong

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Thechallenge

Wave-4residualsinGUVIO/N2 at15oN

Expectationfromtidaldynamics:DE3,SE2,SPW4duetoverticaltidalmotions.Puzzling:PresenceofverystrongDW5,absenceofDE3.

Note:DW5,DE3,SW6,SE2,SPW4areallobservedaswave-4inlocaltimeframe

Thechallenge

ObservedO/N2 amplitudesfordays230-290ingeographicandmagneticcoordinates

DW5,SPW4>DE3inconsistentwithtidaltheory

Latitudedistributioninconsistentwithverticaltidalmotions,looksmorelikeanionospheric signal

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Whatdoweknow?Whatdowenotknow?

O/N2 fromOI@135.6nmandN2 LBHSbands

• 135.6nmalsoduetoO+ recombination(~10%),ignoredinO/N2 retrieval

• Wave-4inO+ duetoE-regiondynamoaction(Immel etal.,GRL2006)

F-regionplasmadensitytidesprimarysourceofwave-4inGUVIO/N2

• Kil andPaxton(GRL2011),Kil etal.(JGR2013)

BUT:Thisdoesn’texplaintheDW5signalsintheO/N2

• WeakDW5inE-regiondynamoregionfromTIDIdiagnostics

• WeakDW5inTEC(>200km)fromCOSMIC(Changetal.,JGR2013)

• DW5inthermospheric windnegligible(tidaltheory);weakinCHAMP(Häusler etal.,JGR2010)andWINDII(Liebermanetal.,JGR2013)diagnostics

Westilldon’tunderstandwhatcauseslarge-scalewavestructuresinobservedO/N2.Needtoclearlyseparatethermospheric fromionospheric signal.

Aroughattempt…

ModeledO/N2 columndensitiesusingDE3andSE2verticaltidalwindsfromtheCTMTmodel

MappedtoGUVIlocaltimesinmagneticcoordinates

Thermospheric signal

Magneticlatitude:20oN

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Aroughattempt…

ObservedGUVIO/N2 columndensitieswiththethermospheric signalremoved

DW5inday230-290windowdisappeared

SuggeststhatDW5isduetoaliasing

Ionospheric signal

Magneticlatitude:20oN

Aroughattempt…

Magneticlatitude:20oN

COSMICTEC(>200km)fromChangetal.(JGR2013)

Wave-4inionospheric GUVIO/N2 signalandCOSMICTECaregenerallyconsistentincludingtheirphasesStilldifferencesinday230-290window:SPW4versusDE3WorkinprogressbutweareapproachingthelimitsofcombinedTIMED/COSMICdiagnostics…

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ICON,GOLD&COSMICDataSynthesis

Large-scalewavesignalsincompositionareimportant• Studyingwaveimpactsontheionospherethroughcompositionvariationsrequires

areclearseparationof“true”thermospheric and“bogus”ionospheric signals• Mayhelptoavoidassimilationof“bogus”O/N2 signalsormayprovide

guidanceforinterpretingtheresultinglarge-scalewavesignals

Needbetterdefinitionoftidaldynamicsinthermosphere• ICONandGOLDdataalongwithCTMT-likeconceptsand

possiblydataassimilationofthedynamicalfields

NeedbetterdefinitionofapparenttidesandPWsinO/N2

• GOLDdataandpossiblydataassimilation;fittingphaseslopestolon/lst residualsasforGUVIhaslimitations

BettertimeresolutionofCOSMIC-2ionospheric tides• Willallowustogetahandonthecausesofshort-termvariabilityinO/N2 from

GOLDandhenceonthetidal“weather”inthethermosphere,possiblyalongwithGBionospheric observations