Electrodynamics–Past,Present,andFuture

TimFuller-Rowell

CIRES,Univ.ofColoradoandSpaceWeatherPredicConCenter,NOAA

June20th,2017 CEDARElectrodynamicsWorkshop

Whatdoyouneedforelectrodynamics?WhatdidweknowinthesixCes?

•  Ionosphere–reasonablemodels,goodobservaCons•  MagneCcfield–offsetdipole•  Neutralatmosphere–composiConanddensity•  AtmosphericmoCon-evolving•  Collisionsbetweentheneutralsandplasma-reasonablywellunderstood

•  Coulombforces•  Lorentzforce•  Collisionalforces–RishbethandGarrioX,1969(ionandelectronmobiliCes)June20th,2017 CEDARElectrodynamicsWorkshop

NeutralThermosphereDynamics

•  KohlandKing1967•  SolarUVandEUV•  Daysidepressurebulge•  Pressure,Coriolis,andiondrag•  Upperthermospherewindsnolongeringeostrophicbalance

•  In-situgenerated(1,-2)Cde–notpropagaCng•  Dayside,lowerthermospherewindsdrivingelectrodynamicwasmissing

June20th,2017 CEDARElectrodynamicsWorkshop

June20th,2017 CEDARElectrodynamicsWorkshop

ClassicalTidalTheorylinearized,separaConofvariable,eigenfuncCons,Houghmodes

propagaCngdiurnal(1,1)andsemi-diurnalCdes(2,2)

June20th,2017 CEDARElectrodynamicsWorkshop

OneofaboutadozenRichmondreviewsoverthefollowing~40years

June20th,2017 CEDARElectrodynamicsWorkshop

ProducCveCmes:J.ForbesandR.S.Lindzen(1976).AtmosphericsolarCdesandtheirelectrodynamiceffects.PartI:TheglobalSqcurrentsystem.J.Atmos.Ter.Phys.

J.ForbesandR.S.Lindzen(1976).AtmosphericsolarBdesandtheirelectrodynamiceffects.PartII:Theequatorialelectrojet.J.Atmos.Ter.Phys.

J.ForbesandR.S.Lindzen(1977).AtmosphericsolarBdesandtheirelectrodynamiceffects.PartIII:Th.epolarizaBonelectricfield.J.Atmos.Ter.Phys.

Heelis,R.(1974).ElectricalcouplingoftheE-andF-regionsanditseffectonF-regiondriQsandwinds.Planet.SpaceSci.

Rishbeth,H.(1971).TheF-layerdynamo.Planet.SpaceSci.

Anderson,D.andR.Roble(1973).TheeffectofverBcalExBionosphericdriQonF-regionneutralwindsinthelow-laBtudethermosphere.J.Geophys.Res.

Matsushita,S.(1969).Dynamocurrents,winds,andelectricfields.RadioSci.

June20th,2017 CEDARElectrodynamicsWorkshop

June20th,2017

1970sThermosphericModels

Volland,MayrandHarrisetal.-spectralmodelwithnon-linearperturbaBon

CreekmoreandStraus,J.M.etal.–notalwaysself-consistent

Dickinsonetal.,zonally-averagedcirculaBon

Emeryetal.,

RichmondandMatsushita,1975

………

June20th,2017 CEDARElectrodynamicsWorkshop

StormcirculaCon:

GravitywavesdrivenbyhighlaCtudemagnetosphericenergysourcesLeadtoaseriesofRichmondpapersongravitywaves

June20th,2017 CEDARElectrodynamicsWorkshop

Equatorwardwindsurges

June20th,2017 CEDARElectrodynamicsWorkshop

Consequences:disturbancedynamotheory

June20th,2017 CEDARElectrodynamicsWorkshop

Storm-TimeElectrodynamics:disturbancedynamoBlanc and Richmond (1980) theory:

•  Equatorward winds drive zonal winds at mid-latitude through the action of the Coriolis force •  Zonal winds → equatorward Pedersen current •  Equatorward wind → equatorward Hall current •  Positive charge builds up at the equator producing a poleward directed electric field which balance the wind driven equatorward current •  Poleward electric field drives an eastward Hall current causes +ve charge build up at the dusk terminator and -ve charge build-up at dawn •  Reverse Sq

€

Jϑu = −σ1sin I

uφB +σ 2uθB

Jφu =σ1 sin IuθB +σ 2uφB

JθE =σ1sin I

Eε +σ 2

sin IEφ

JφE = −σ 2Eε +σ1Eφ

June20th,2017 CEDARElectrodynamicsWorkshop

1980sandearly90s

•  Globalthree-dimensional,non-linear,thermospheremodelsdeveloped–windsandtemperature(NCARandUCL)

•  Coupledwiththree-speciescomposiCon•  Coupledtoanionosphere•  Tidalforcingatthelowerboundary–Fesen,Parish,Ingo-Mueller-Wodarg

•  Electrodynamiccoupling-Richmondetal.1987;1992

June20th,2017 CEDARElectrodynamicsWorkshop

SourceofElectrodynamicDrifontheDayside

noCdes

600m

300m

verCcaliondrifatmagneCcequatordrivenbydifferentmagnitudesof(2,2)semi-diurnal

Houghmode

JicamarcadataScherliessandFejer

CTIPemodel

NmF2

UCL–SheffieldModelCTIPMillward,1993,Millwardetal.1996CoupledelectrodynamicsMillwardetal.,2001

usingRichmondsolver

Disturbance Dynamo vs Magnetospheric Penetration Nightside Electric Fields

Systemtheoryapproach:solarwind/magnetospheredriverKelleyetal.

Physicalmodelapproach:disturbancedynamoMaruyamaetal:

June20th,2017 CEDARElectrodynamicsWorkshop

EastwardElectricField

SouthwardNeutralWind

CEDARElectrodynamicsWorkshop

Rapidresponse

€

Jϑu = −σ1sin I

uφB +σ 2uθB

Jφu =σ1 sin IuθB +σ 2uφB

JθE =σ1sin I

Eε +σ 2

sin IEφ

JφE = −σ 2Eε +σ1Eφ

June20th,2017

June20th,2017 CEDARElectrodynamicsWorkshop

Scherliess and Fejer, JGR, 1999

Contribution of observations to empirical models (Fejer and Scherliess)

• Vertical ion drifts have strong diurnal variation - up during the day and down at night.

• Variability is high.

• Pre-reversal enhancement is a strong function of season and solar activity.

• E-region dynamo explains the diurnal variation, F-region the pre-reversal enhancement

Quiet

Storm

Other examples: 50% increase in TEC in January 2009 when solar and geomagnetic activity were very low

Goncharenko et al. 2010

IsthisalsoaresponsetochangingCdalamplitudes?

•  CTIPesimulaConswithWAMwinds(lowerpanel)appeartoreproducethemainfeaturesintheobservedverCcalplasmadrif(upperpanel)duringaSSW,includingthestrongerupwarddrifearlyinthemorningandreversaltodownwardintheafernoon

•  LargestCdalchangesduringintervalareinSW2andTW3

June 20th, 2017

Chauetal.

Fuller-Rowelletal.2011 CEDARElectrodynamicsWorkshop

average95-155km,20–60°north

SW2

TW3

What’s the physics? Three possibilities… •  AmplificaConoflunarCde (JeffForbes)

Eccles

•  Changeinozoneforcing(LarisaGoncharenko)

•  ChangeinCdalpropagaConthroughthealteredbackground

winds

CEDAR Electrodynamics Workshop June20th,2017

ExampleofimpactofCdalvariabilityTzu-WeiFang,ArtRichmond,GeorgeMillward,etal.fromWAM-GIPmodelsimulaConwithRichmond’selectrodynamicssolverwithIGRFinAPEXcoords

June20th,2017 CEDARElectrodynamicsWorkshop

ModulaConofsemi-diurnalCdeSW2correlateswithincreasesinpeakverCcal

plasmadrifandNmF2

ModulaConofDE3andDE2Cdalamplitudescorrelateswithnumberofpeaksinlongitude

structureofverCcalplasmadrif

Future

•  InteracConbetweenmagnetosphericanddynamoelectrodynamics

•  Understandingtheforcingfromtheloweratmosphere–Cdes,gravitywaves,etc.

•  HighresoluConwholeatmospheremodelswithcoupledionosphereandelectrodynamics

•  ElectrifiedMS-TIDs–e.g.,Kelly,PerkinsinstabiliCes•  RelaConshipbetweenmesoscaledynamicsand

electrodynamicsandsmall-scaleionosphericirregulariCes•  B,VvsE,Jparadigm•  Co-rotaCon

June20th,2017 CEDARElectrodynamicsWorkshop