Ionospheric Effects during Severe Geomagnetic Storms John Foster MIT Haystack Observatory NASA CDAW Mar. 14, 2005

Ionosphere / Storm Effects Ionospheric Conductivity (E & F Region) Affects Magnetospheric Currents Ionospheric Conductivity (E & F Region) Affects Magnetospheric Currents Cold Plasma Redistribution Alters I-T Flywheel Coupling and Energy Dissipation Cold Plasma Redistribution Alters I-T Flywheel Coupling and Energy Dissipation Cold Plasma in Msph Alters W-P Interactions Cold Plasma in Msph Alters W-P Interactions Plasmaspheric Material Injected into Tail and Plasma Sheet as Erosion Plumes Enter Cusp Plasmaspheric Material Injected into Tail and Plasma Sheet as Erosion Plumes Enter Cusp I-M Coupling in SAPS Affects Ring Current Development I-M Coupling in SAPS Affects Ring Current Development

Visualizing the Initial Stages of an Ionospheric Storm

GPS samples the ionosphere and plasmasphere to an altitude of ~20,000 km TEC is a measure of integrated density in a 1 m 2 column 1 TEC unit = electrons m -2

Stormtime Ionosphere The low and mid-latitude ionosphere is strongly perturbed during geomagnetic disturbances The low and mid-latitude ionosphere is strongly perturbed during geomagnetic disturbances Low-latitude cold plasma is carried throughout the M-I system by disturbance electric fields. Low-latitude cold plasma is carried throughout the M-I system by disturbance electric fields. Storm Enhanced Density (SED) forms at Equatorward Edge of Ionospheric Trough Storm Enhanced Density (SED) forms at Equatorward Edge of Ionospheric Trough Ionospheric conductance shapes magnetospheric electric fields (e.g. SAPS – Sub-Auroral Polarization Stream) Ionospheric conductance shapes magnetospheric electric fields (e.g. SAPS – Sub-Auroral Polarization Stream)

Today’s Weather: NEXRAD Observations of Storm Front over N. America

Analysis & Understanding are Well Developed

Space Weather Storm Fronts (GPS TEC Observations) [Foster et al. GRL 2002]

Millstone Hill IS Radar IS Radar Observes Storm Enhanced Density [Foster, JGR, 1993]

Ionos Storm Characteristics are Repeatable

WG3 Questions: Ionospheric Storms 1) What Happens during the first 60 min of a Storm? 1) What Happens during the first 60 min of a Storm? 2) What is the Source of the SED at Mid Latitudes? 2) What is the Source of the SED at Mid Latitudes? 3) What are the Impacts of Neutral Wind Effects? 3) What are the Impacts of Neutral Wind Effects? 4) How is the Plasma Bulge Created? 4) How is the Plasma Bulge Created? 5) Can Models Describe the O/N2 Changes? 5) Can Models Describe the O/N2 Changes? 6) Why is there a Longitude Dependence of the TEC response to storms? 6) Why is there a Longitude Dependence of the TEC response to storms?

WG3 Data Sets Characterize Ionospheric Effects and Address the Mechanisms Behind Them

Spin Up of Neutrals in E Region during Superstorms Millstone Hill Lower Thermosphere Observations [Goncharenko et al, JGR, 2004](cf. G. Siscoe CDAW tutorial)

Space Weather Effects of Ionospheric Cold Plasma Redistribution Steep Mid Latitude TEC Gradients Steep Mid Latitude TEC Gradients Radiation Belt Modification - Greatly Eroded Plasmasphere - Loss of Radiation Belt Particles Radiation Belt Modification - Greatly Eroded Plasmasphere - Loss of Radiation Belt Particles Ionospheric Irregularities & Scintillation Ionospheric Irregularities & Scintillation Equatorial / Low-Latitude Ionospheric Perturbation (Spread F) Equatorial / Low-Latitude Ionospheric Perturbation (Spread F) Ionospheric Perturbation at Polar Latitudes - Polar Tongue of Ionization Ionospheric Perturbation at Polar Latitudes - Polar Tongue of Ionization

SED Plume forms Polar Tongue of Ionization Merged SuperDARN/DMSP Convection GPS TEC Map [Foster et al., JGR 2004]

Space Weather: Severe TEC Gradients over CONUS

IMAGE EUV observations: SED Plumes accompany Plasmasphere Erosion April 11, 2001

Extreme Space Weather: Oct 2003 Superstorm Severe Plasmasphere Erosion (EUV images courtesy J. Goldstein)

Sunward Poleward TEC Plume Mapped to Equatorial Plane

Space Weather: Radiation Belt Modification High-Energy Electrons: 17 Oct.-1 Dec. (Courtesy: D. Baker)

Regions of Wave-Particle Interactions (Courtesy: D. Baker)

Energetic Ion Precipitation on Plume Field Line plasmapause EMIC Waves SAPS

Destabilization of Ion Waves in Detached Plasma Regions N Hemis; L~2.5~6 sec period Sub-Auroral Polarization Stream

What Drives the Erosion Plume? Sub-Auroral Polarization Stream (SAPS) Strong Stormtime Electric Fields appear between the plasmasheet and the plasmapause Statistical Studies indicate the Persistence and Predictability of the Polarization Stream Statistical Studies indicate the Persistence and Predictability of the Polarization Stream Storm Enhanced Density is formed where the Polarization Stream overlaps the Plasmasphere Storm Enhanced Density is formed where the Polarization Stream overlaps the Plasmasphere Polarization Electric Fields Structure the Outer Plasmasphere forming Plasmaspheric Tails Polarization Electric Fields Structure the Outer Plasmasphere forming Plasmaspheric Tails

Sub-Auroral Polarization Stream Plasmasheet Plasmapause SAPS DMSP F15 6 April 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 into Sub-Auroral Ionosphere REGION 2 REGION 1 (Slide courtesy D. Mitchell)

AURORAL OVAL LOW  SAPS E FIELD Ring Current / SAPS/ SED Plume (Sub Auroral Polarization Stream Electric Field) Duskside Region-2 FACs close poleward across low- conductance gap Duskside Region-2 FACs close poleward across low- conductance gap SAPS: Strong poleward Electric Fields are set up across the sub-auroral ionosphere SAPS: Strong poleward Electric Fields are set up across the sub-auroral ionosphere SAPS erodes the outer plasmasphere SAPS erodes the outer 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

Magnetic Local Time L=4 L=3 Average Latitude of SAPS

Empirical 2-Cell Convection plus SAPS Electric Field Geo-effective Convection Pattern: Two-Cell Auroral Convection & SAPS

March 31, 2001 DMSP F13 SAPS Erodes Outer Plasmasphere

TEC Hole Enhanced Eq Anomaly Plume Bulge Where does the SED Plasma Come From? Inner Magnetosphere – Low Latitude View

Low-Latitude Ionosphere & Plasmasphere: Effects of Sub-Auroral Disturbance Electric Fields Undershielded eastward electric field: Strong uplift at equator redistributes plasma to higher latitudes Undershielded eastward electric field: Strong uplift at equator redistributes plasma to higher latitudes Mid-Latitude TEC: Spread EA & Bulge: Downwelling & poleward/sunward plasma transport increase TEC at low & mid latitudes Mid-Latitude TEC: Spread EA & Bulge: Downwelling & poleward/sunward plasma transport increase TEC at low & mid latitudes SED/TEC plumes & plasma tails: SAPS overlaps outer plasmasphere (PBL) carrying thermal plasma sunward SED/TEC plumes & plasma tails: SAPS overlaps outer plasmasphere (PBL) carrying thermal plasma sunward

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

Spread F (Bubbles) in Enhanced TEC Region [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 Redistribution Similar Structure TEC hole

21 UT

Another Example - Similar Structure

May 29/30, UT

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

Space-Based View of May 2003 Event

Bulge seen from Ground by GPS TEC

285 E long

March 31, :08 UT 285 E Longitude Corotating Plasmaspheric Bulge

Ionosphere / Storm Effects Ionospheric Conductivity (E & F Region) Affects Magnetospheric Currents Ionospheric Conductivity (E & F Region) Affects Magnetospheric Currents Cold Plasma Redistribution Alters I-T Flywheel Coupling and Current Dissipation Cold Plasma Redistribution Alters I-T Flywheel Coupling and Current Dissipation Cold Plasma Alters W-P Interactions Cold Plasma Alters W-P Interactions Plasmaspheric Material Injected into Tail and Plasma Sheet as Erosion Plumes Enter Cusp Plasmaspheric Material Injected into Tail and Plasma Sheet as Erosion Plumes Enter Cusp I-M Coupling in SAPS Affects Ring Current Development I-M Coupling in SAPS Affects Ring Current Development

Mid-Latitude SED forms a source for the Polar TOI (as Dst Falls)

October 29/30, 2003 Storm Global Thermal Plasma Redistribution Global TEC (Noon in center) Southern Hemisphere Northern Hemisphere

Points to Remember Electric Fields Map between Altitude Regimes Independent of their Source (This is especially true in the Inner Magnetosphere where parallel electric fields usually can be ignored) Electric Fields Map between Altitude Regimes Independent of their Source (This is especially true in the Inner Magnetosphere where parallel electric fields usually can be ignored) The Bulk of Thermal Plasma is of Ionospheric Origin (Solar production at low altitude/latitude) The Bulk of Thermal Plasma is of Ionospheric Origin (Solar production at low altitude/latitude) Thermal Plasma Dynamics is Controlled by the Electric Field (ExB) Thermal Plasma Dynamics is Controlled by the Electric Field (ExB) Ionospheric effects Map into the Magnetosphere Ionospheric effects Map into the Magnetosphere

Ionospheric Storm Fronts During strong geomagnetic disturbances, greatly-enhanced ionospheric total electron content (TEC) develops at mid latitudes in the post-noon sector During strong geomagnetic disturbances, greatly-enhanced ionospheric total electron content (TEC) develops at mid latitudes in the post-noon sector Plumes of storm-enhanced density (SED) are swept toward the cusp ionosphere by the sub-auroral (SAPS) electric field Plumes of storm-enhanced density (SED) are swept toward the cusp ionosphere by the sub-auroral (SAPS) electric field Plasma Redistribution Spans Equatorial – Mid - Auroral – and Polar Latitudes Plasma Redistribution Spans Equatorial – Mid - Auroral – and Polar Latitudes

Why the Big Effect in the Atlantic Sector? Polarization E Field at Conductivity Gradient (Sunset Terminator ~ 21 UT) E pol E east  18LT 00LT 06LT East – West E Field Pre-reversal enhancement V z ~ E/|B| |B| 30% smaller near SAA