Ionospheric EffectsIonospheric Effectsduringduring

Severe Geomagnetic Severe Geomagnetic StormsStorms

John FosterJohn FosterMIT Haystack ObservatoryMIT Haystack Observatory

NASA CDAW Mar. 14, NASA CDAW Mar. 14, 20052005

Ionosphere / Storm EffectsIonosphere / Storm Effects

Ionospheric ConductivityIonospheric Conductivity (E & F (E & F Region) Affects Magnetospheric CurrentsRegion) Affects Magnetospheric Currents

Cold Cold Plasma Redistribution Alters I-T Plasma Redistribution Alters I-T FlywheelFlywheel Coupling and Energy Coupling and Energy DissipationDissipation

Cold Plasma in Msph Alters Cold Plasma in Msph Alters W-P W-P InteractionsInteractions

Plasmaspheric Material Injected intoPlasmaspheric Material Injected into Tail and Tail and Plasma SheetPlasma Sheet as Erosion as Erosion Plumes Enter CuspPlumes Enter Cusp

I-M Coupling in SAPSI-M Coupling in SAPS Affects Ring Affects Ring Current DevelopmentCurrent Development

Visualizing the Initial Stages of an Visualizing the Initial Stages of an Ionospheric StormIonospheric Storm

GPS samples the ionosphere and plasmasphere to an altitude of ~20,000 km

TEC is a measure of integrated density in a 1 m2 column

1 TEC unit = 1016 electrons m-2

Stormtime IonosphereStormtime Ionosphere

The low and mid-latitude ionosphere is The low and mid-latitude ionosphere is strongly perturbed during geomagnetic strongly perturbed during geomagnetic disturbancesdisturbances

Low-latitude cold plasma is carried Low-latitude cold plasma is carried throughout the M-I system by throughout the M-I system by disturbance electric fields.disturbance electric fields.

Storm Enhanced Density (SED) forms at Storm Enhanced Density (SED) forms at Equatorward Edge of Ionospheric TroughEquatorward Edge of Ionospheric Trough

Ionospheric conductance shapes Ionospheric conductance shapes magnetospheric electric fields magnetospheric electric fields (e.g. SAPS – Sub-Auroral Polarization (e.g. SAPS – Sub-Auroral Polarization Stream)Stream)

Today’s Weather: NEXRADToday’s Weather: NEXRADObservations of Storm Front over N. Observations of Storm Front over N.

AmericaAmerica

Analysis & Understanding are Well Analysis & Understanding are Well DevelopedDeveloped

Space Weather Storm Fronts (GPS TEC Space Weather Storm Fronts (GPS TEC Observations)Observations)

[Foster et al. GRL 2002]

Millstone Hill IS Radar

IS Radar Observes Storm Enhanced Density

[Foster, JGR, 1993]

Ionos Storm Characteristics are Ionos Storm Characteristics are RepeatableRepeatable

WG3 Questions: Ionospheric StormsWG3 Questions: Ionospheric Storms

1) What Happens during the 1) What Happens during the first 60 first 60 minmin of a Storm? of a Storm?

2) What is the 2) What is the Source of the SEDSource of the SED at at Mid Latitudes?Mid Latitudes?

3) What are the 3) What are the Impacts of Neutral Impacts of Neutral WindWind Effects? Effects?

4) How is the 4) How is the Plasma BulgePlasma Bulge Created? Created? 5) Can Models Describe the 5) Can Models Describe the O/N2 O/N2

ChangesChanges?? 6) Why is there a 6) Why is there a Longitude Longitude

DependenceDependence of the TEC response to of the TEC response to storms?storms?

WG3 Data Sets WG3 Data Sets Characterize Characterize

Ionospheric Effects Ionospheric Effects and Address the and Address the

Mechanisms Behind Mechanisms Behind ThemThem

Spin Up of Neutrals in E Region during Spin Up of Neutrals in E Region during SuperstormsSuperstorms

Millstone Hill Lower Thermosphere ObservationsMillstone Hill Lower Thermosphere Observations

[Goncharenko et al, JGR, 2004]

(cf. G. Siscoe CDAW tutorial)

Space Weather EffectsSpace Weather Effectsof Ionospheric Cold Plasma of Ionospheric Cold Plasma

RedistributionRedistribution Steep Mid Latitude TEC GradientsSteep Mid Latitude TEC Gradients Radiation Belt ModificationRadiation Belt Modification

- Greatly Eroded Plasmasphere- Greatly Eroded Plasmasphere- Loss of Radiation Belt Particles- Loss of Radiation Belt Particles

Ionospheric Irregularities & Ionospheric Irregularities & ScintillationScintillation

Equatorial / Low-Latitude Equatorial / Low-Latitude Ionospheric Perturbation (Spread F)Ionospheric Perturbation (Spread F)

Ionospheric Perturbation at Polar Ionospheric Perturbation at Polar LatitudesLatitudes

- Polar Tongue of Ionization- Polar Tongue of Ionization

SED Plume SED Plume forms Polar forms Polar Tongue of Tongue of IonizationIonization

Merged SuperDARN/DMSP Convection

GPS TEC Map

[Foster et al., JGR 2004]

Space Weather: Severe TEC Gradients Space Weather: Severe TEC Gradients over CONUSover CONUS

IMAGE EUV observations:IMAGE EUV observations:SED Plumes accompany Plasmasphere SED Plumes accompany Plasmasphere

ErosionErosion

April 11, 2001

Extreme Space Extreme Space Weather:Weather:Oct 2003 Oct 2003

SuperstormSuperstorm

Severe Severe Plasmasphere Plasmasphere

ErosionErosion

(EUV images courtesy J. Goldstein)

Sunward

Poleward

TEC Plume Mapped to Equatorial Plane

Space Weather: Radiation Belt Space Weather: Radiation Belt ModificationModification

High-Energy Electrons: 17 Oct.-1 Dec.High-Energy Electrons: 17 Oct.-1 Dec.

(Courtesy: D. Baker)

Regions of Wave-Particle InteractionsRegions of Wave-Particle Interactions

(Courtesy: D. Baker)

Energetic Ion Precipitation on Plume Energetic Ion Precipitation on Plume Field LineField Line

plasmapause

EMIC Waves

SAPS

Destabilization of Ion WavesDestabilization of Ion Wavesin Detached Plasma Regionsin Detached Plasma Regions

N Hemis; L~2.5 ~6 sec period

Sub-Auroral Polarization Stream

What Drives the Erosion Plume?What Drives the Erosion Plume?

Sub-Auroral Polarization Stream Sub-Auroral Polarization Stream (SAPS)(SAPS)

Strong Stormtime Electric Fields appear between the plasmasheet and the plasmapause

Statistical Studies indicate the Statistical Studies indicate the Persistence Persistence and Predictabilityand Predictability of the Polarization Stream of the Polarization Stream

Storm Enhanced Density is formed where the Storm Enhanced Density is formed where the Polarization Stream overlaps the Polarization Stream overlaps the PlasmaspherePlasmasphere

Polarization Electric Fields Structure the Polarization Electric Fields Structure the Outer Plasmasphere forming Outer Plasmasphere forming Plasmaspheric Plasmaspheric TailsTails

Sub-Auroral Polarization StreamSub-Auroral Polarization Stream

Plasmasheet

Plasmapause

SAPS

DMSP F15 6 April 2000 21 MLT

Trough

A Strong Electric Field forms in the Low-Conductivity Region between the Inner Edge of the Plasmasheet Precipitation and the Plasmapause

Plasmapause

2-Cell Convection

EXTENDING TO PLASMASHEET

Magnetospheric Driver:

Disturbed Ring Current

drives FAC intoSub-Auroral Ionosphere

REGION 2

REGION 1

(Slide courtesy D. Mitchell)

AURORAL OVAL

LOW

SAPS E FIELD

Ring Current / SAPS/ SED PlumeRing Current / SAPS/ SED Plume(Sub Auroral Polarization Stream Electric (Sub Auroral Polarization Stream Electric

Field)Field)

Duskside Region-2 Duskside Region-2 FACs close poleward FACs close poleward across low-across low-conductance gapconductance gap

SAPS: Strong SAPS: Strong poleward Electric poleward Electric Fields are set up Fields are set up across the sub-auroral across the sub-auroral ionosphereionosphere

SAPS erodes the SAPS erodes the outer plasmasphereouter plasmasphere

Millstone Hill Radar Scans Span Auroral and Polarization Stream Convection

20-Year Database used to Determine Statistical Features

Polarization Stream

Trough

L=4L=2

Plasmasphere

Millstone Hill Azimuth Scan April 12, 2001 UT Westward Ion Velocity

16 18 20 22 00 02 04 06 08Magnetic Local Time

L=4

L=3

Average Latitude of SAPS

Empirical 2-Cell Convection plus SAPS Electric Field

Geo-effective Convection Pattern:Geo-effective Convection Pattern:Two-Cell Auroral Convection & SAPSTwo-Cell Auroral Convection & SAPS

March 31, 2001DMSP F13

SAPS Erodes Outer

Plasmasphere

TEC Hole

EnhancedEq

Anomaly

Plume

Bulge

Where does the SED Plasma Come From?Where does the SED Plasma Come From?Inner Magnetosphere – Low Latitude Inner Magnetosphere – Low Latitude

ViewView

Low-Latitude Ionosphere & Low-Latitude Ionosphere & Plasmasphere:Plasmasphere:

Effects of Sub-AuroralEffects of Sub-AuroralDisturbance Electric FieldsDisturbance Electric Fields

Undershielded eastward electric field: Undershielded eastward electric field: Strong uplift at equator redistributes Strong uplift at equator redistributes plasma to higher latitudesplasma to higher latitudes

Mid-Latitude TEC: Spread EA & BulgeMid-Latitude TEC: Spread EA & Bulge::Downwelling & poleward/sunward Downwelling & poleward/sunward plasma transport increase TEC at low plasma transport increase TEC at low & mid latitudes & mid latitudes

SED/TEC plumes & plasma tails:SED/TEC plumes & plasma tails:SAPS overlaps outer plasmasphere SAPS overlaps outer plasmasphere (PBL) carrying thermal plasma (PBL) carrying thermal plasma sunwardsunward

[References: Greenspan et al. (March 1989 storm); Basu et al. (July 2000 storm)]

Bubbles

TEC hole

Spread F Spread F (Bubbles) in (Bubbles) in

Enhanced TEC Enhanced TEC RegionRegion

[Foster & Rich, 1998][Foster & Rich, 1998]

(Courtesy: J. Makela)

Equatorial Anomalies Spread Poleward

TEC Hole

Poleward SAPS Electric Field Strips Away Outer Layers of Plasmasphere

Key West

Guiana

GPS Samples Ionosphere/Plasmasphere

TEC

21:00 UT

Uplift

Downwelling

Guiana

Key West

October 30, 2003 Plasma October 30, 2003 Plasma RedistributionRedistribution

Similar Structure

TEC hole

21 UT

Another Example - Similar Structure

May 29/30, 2003

21 UT

Watch for formation of Bulge at 19:30 UTWatch for formation of Bulge at 19:30 UT(6 hours later – Bulge remains at 285 E longitude)(6 hours later – Bulge remains at 285 E longitude)

Space-Based View of May 2003 EventSpace-Based View of May 2003 Event

Bulge seen from Ground by GPS TEC

285 E long

March 31, 2001 19:08 UTMarch 31, 2001 19:08 UT

285 E Longitude Corotating Plasmaspheric

Bulge

Ionosphere / Storm EffectsIonosphere / Storm Effects

Ionospheric ConductivityIonospheric Conductivity (E & F (E & F Region) Affects Magnetospheric CurrentsRegion) Affects Magnetospheric Currents

Cold Cold Plasma Redistribution Alters I-T Plasma Redistribution Alters I-T FlywheelFlywheel Coupling and Current Coupling and Current DissipationDissipation

Cold Plasma Alters Cold Plasma Alters W-P InteractionsW-P Interactions Plasmaspheric Material Injected intoPlasmaspheric Material Injected into

Tail and Tail and Plasma SheetPlasma Sheet as Erosion as Erosion Plumes Enter CuspPlumes Enter Cusp

I-M Coupling in SAPSI-M Coupling in SAPS Affects Ring Affects Ring Current DevelopmentCurrent Development

Mid-Mid-Latitude Latitude

SED forms a SED forms a source for source for

thethePolar TOIPolar TOI(as Dst Falls)(as Dst Falls)

October 29/30, 2003 October 29/30, 2003 StormStorm

Global Thermal Global Thermal PlasmaPlasma

RedistributionRedistribution

Global TEC (Noon in center)

Southern Hemisphere

Northern Hemisphere

Points to RememberPoints to Remember

Electric Fields Map between Altitude Electric Fields Map between Altitude Regimes Independent of their Source Regimes Independent of their Source (This is especially true in the Inner (This is especially true in the Inner Magnetosphere where parallel Magnetosphere where parallel electric fields usually can be ignored)electric fields usually can be ignored)

The Bulk of Thermal Plasma is of The Bulk of Thermal Plasma is of Ionospheric Origin (Solar production Ionospheric Origin (Solar production at low altitude/latitude)at low altitude/latitude)

Thermal Plasma Dynamics is Thermal Plasma Dynamics is Controlled by the Electric Field (ExB)Controlled by the Electric Field (ExB)

Ionospheric effects Map into the Ionospheric effects Map into the MagnetosphereMagnetosphere

Ionospheric Storm FrontsIonospheric Storm Fronts

During strong geomagnetic During strong geomagnetic disturbances, disturbances, greatly-enhanced greatly-enhanced ionosphericionospheric total electron content total electron content (TEC)(TEC) develops at mid latitudes in the develops at mid latitudes in the post-noon sectorpost-noon sector

Plumes of Plumes of storm-enhanced density storm-enhanced density (SED)(SED) are swept toward the cusp are swept toward the cusp ionosphere by the sub-auroral (SAPS) ionosphere by the sub-auroral (SAPS) electric fieldelectric field

Plasma RedistributionPlasma Redistribution Spans Equatorial Spans Equatorial – Mid - Auroral – and Polar Latitudes– Mid - Auroral – and Polar Latitudes

Why the Big Effect in the Atlantic Sector?Why the Big Effect in the Atlantic Sector?

Polarization E Field at Conductivity Polarization E Field at Conductivity GradientGradient

(Sunset Terminator ~ 21 UT)(Sunset Terminator ~ 21 UT)

Epol Epol

Eeast

18LT 00LT

06LT

East – West E Field

Pre-reversal enhancement

Vz ~ E/|B|

|B| 30% smaller near SAA