Event Goals and Focus Areas:

Event Study Goal

To follow a significant solar-terrestrial event from its origin at the Sun and to trace the flow of particles and energy from the subsequent magnetic storm through the dissipative elements of the magnetosphere, ionosphere and thermosphere.

Solar Relations to Study

Identification and Timing of Solar Drivers at the Leading Edge of the Storm

GEM Focus Area

Global Energy Flow Analysis Through Magnetic Storms:

How do energy and particles flow from the solar wind into and through the Magnetosphere and distribute themselves in various dissipation elements of the magnetosphere, ionosphere and neutral atmosphere?

General Magnetospheric Relations to Study and Understand

1. Solar Wind Drivers--Initial and Main Phase of Storm
2. Onset and Decline of Main Phase
3. Modes of Recovery
4. Role of Field Aligned Currents in Energy Transfer Process
   Convection-Ring Current Decay
   Substorm-Dst relations
5. Relative Contributions of Convection and Charge Exchange

Specific Magnetospheric Relations for This Study

1. ULF Wave Activity and Storm Timing
   a. Do ULF waves play a role in particle accelerations
2. Geosynchronous Energetic Particle Dynamics
   a. Where do particles go when they are depleted?
   b. How do populations get rebuilt?
3. Variations in plasmaspheric drifts appear correlated to Kp
   a. Is the causal or incidental?
4. Variations in Energetic Electrons associated with particular coronal hole
   a. What was unique in the solar terrestrial environment that generated enhanced populations of 6.0- 7.8 MeV electrons during the recurrences of this particular coronal hole

CEDAR Focus Areas

Identify Limitations and Deficiencies in Observations and Models.
Explore new modeling and data assimilation methods. Ionospheric Relations to Study, Understand and/or Validate:

1. Global Description of Neutral Winds, Temperatures and Neutral Composition
2. Global Description of Joule heating
3. Dynamics of the Low Latitude Trough
4. High and Mid Latitude Convection Dynamics Relating to Magnetosphere and Thermosphere Changes
5. Structuring of High Latitude Patches, Polar Cap Arcs and Scintillation
6. Ionospheric Morphology as Sensed by Ground and Space-Based Tomography
7. Plasmaspheric Morphology and Dynamics as they relate to Ionospheric Variations
8. Energy Transfer to the Mesosphere
9. Model Validation
10. Ionospheric Signatures of Substorm Onset

---

Event selection based on:

Major magnetic storm classification (-105 nT Dst)

Availability of solar wind at storm onset

Reported storm Ionospheric/Magnetospheric effects

Status as recurrent activity

Likely association with increased flux of relativistic electrons

Availability of magnetospheric data from satellites

Solar/Solar Wind Background

Mid 1993-Mid 1994: Robust, recurrent geomagnetic storms (Geomagnetic indices, geosynchronous satellites, SAMPEX satellite, D. Baker 1995 GEM and CEDAR presentations)

Late 1993: Sector boundary structure began to reorganize (S. Watari, 1995 IUGG presentation)

Early November 1993 storm was 4th recurrence out of 5 associated with long-lived coronal hole and high speed recurrent stream (Aug- Nov 93 Ap index, Aug-Dec Dst index, IMP-8 plasma data, Yohkoh soft X-ray images, D. Knipp 1995 GEM,CEDAR, SIP and SOLTIP presentations)

In each of 5 recurrences enhancements of 6.0-7.8 Mev magnetospheric electrons observed by LANL geosynchronous satellites. Similar enhancements were not seen in other high speed streams during this interval (G. Reeves).

Yohkoh imagery clearly showed coronal hole from 30 Oct and subsequent days (Yohkoh imagery, A. McAllister)

Mauna Loa K-Coronometer shows faint CME on east solar limb at 2000 - 2100 UT on 31 Oct (High Altitude Observatory NCAR, A. Hundhausen). The impact of this ejection, if any, on the early November 1993 storm remains to be determined.

An M-class flare associated with an active region near the coronal hole was observed at 2230 UT on 1 Nov (Yohkoh Imagery and GOES-7 Xray observations) Impact, if any, on early November 1993 storm remains to be determined.

Magnetosphere/Ionosphere

• Kp index in 0 to 1- range,
• IMP-8 in duskside magnetosheath at ~-25 Re (A. Lazarus)
• GEOTAIL at duskside magnetosheath at ~-200 Re (M. Nakamura)

• Sudden increase in solar wind plasma density.Solar wind density increased sufficiently to allow IMP-8 to sense solar wind plasma characteristics. IMP-8 apparently remained in the magnetosheath. (A. Lazarus)
• Solar wind velocity ~275 km/s
• Cross polar cap voltages ~ 30 kV (M. Hairston)

• Large anisotropy in ring current ions developed,
• Smaller anisotropy in plasma sheet electrons (G. Hoogeveen and LANL MPA team)
• Dst positive phase begins

• ~1720 UT Sudden Commencement (SC)
• Sparse IMP-8 data indicates velocity jump and density enhancement, but small magnetic field components at SC (A. Lazarus, R. Lepping)
• ~1800 UT Plasmasphere disappeared from nightside geosynchronous satellites but remained on dayside (G. Hoogeveen and LANL MPA team)
• Dst began to decline
• Polar Cap Index began to rise
• Ground magnetic observatories and polar satellites record small to moderate responses (D. Knipp, data gathered for assimilation)
• Southern hemisphere riometer absorption event observed (T. Rosenberg)
• ~ 1830 UT GEOTAIL observed sudden jump in magnetic field intensity, associated with shock arrival. Solar wind speeds measured in the magnetosheath increased from 300 km/s to 350 km/s (M. Nakamura)

• IMF northward, ionosphere and ground activity quiet (D. Knipp, data gathered for assimilation)

• IMF turns moderately southward (-5 nT), SuperDARN radars observe clear duskside response (K. Baker and M Ruohoniemi)
• Ionosphere and ground activity enhancements begin (D. Knipp, data gathered for assimilation)

• IMF strongly southward (-15 nT) ionosphere and ground disturbances continue (D. Knipp, data gathered for assimilation)

• Possible magnetic flux rope passage (N. Crooker, J. Foster) IMF northward-southward-northward, southward magnitudea ~ 35 nT
• Other components also changing polarity Hour long extreme density enhancement (> 75/cc at peak) Thermal speed decreased with density enhancement
• 500-800 nT magnetic bays near local midnight (H. Leuhr, IMAGE data and C. Szuberla, Lonyearyben data)
• 300-500 nT bays beyond midnight (G. Rostoker, CANOPUS, J. Hughes MACCS, E. Friis-Christensen, Greenland data) LI>Millstone Hill Radar recorded prompt onset of precipitation produced ionization at lower F-region heights near L=4 in evening sector and at L=3.5 a deep ionization trough (J. Foster)
• Beginning of more than 12-hour complete depletion of SAMPEX observed energetic electrons (>3.0 MeV) at 3 < L < 8 (X. Li)

• Millstone Hill observed ionospheric F-region uplift indicating deep penetration of disturbance electric fields to low latitudes (L < 2) ( J. Foster)
• LANL geosynchronous satellites near local noon encountered magnetosheath for short time, indicating magnetopause was inside geosynchronous orbit (J. Borovsky, G. hoogeveen, and LANL MPA team)
• IMP-8 observes solar plasma flow angle suddenly shift to come from west of sun ( A. Lazarus)
• ~01 UT IMP-8 observes continuous southward field of -25 nT until rapid entry into magnetosphere at ~ 01 UT

• Kp maximized at 6-
• Ap maximized at 78
• Dst minimized at -105 nT
• IMP-8 in magnetosphere, other data gives strong credence to ongoing southward IMF conditions and high speed flow
  • Antisunward convecting F region patches (D. McEwen)
  • Antisunward flow observed by DMSP satellites (M. Hairston)
  • Ongoing nightside magnetic bays (ground mag observatories)
  • ULF wave activity in morning sector, possibly associated with development increased flux of relativistic electrons at Geosynchronous orbit(G. Rostoker)
• Positive phase ionospheric storm begins **NOTE this is different than positive phase DST,** Southern hemisphere ionosondes see storm progress equatorward. Ionosonde data lost from Mawson and MacQuarie Island due to strong absorption (P. Wilkinson)
• ~0515 GEOTAIL observed a solar wind speed increase to a maximum of 700 km/s. The speed remained at the at level for the rest of the day.(M. Nakamura )

• 00 UT -12 UT Strong, stable nightside field-aligned current structures sensed by FREJA satellite (J. Gary and L. Zanetti )
• ~22 UT Extreme, but short lived disturbance at nightside ground and satellite locations. Source and characteristics of disturbance remain to be determined (D. Knipp, assimilated data)
• Preliminary AMIE results indicate cross-polar cap voltages in excess of 160 kV (D. Knipp and B. Emery)

• IMF apparently goes northward for a few hours. Stable sun aligned arcs observed by Eureka MSP (D. McEwen)
• ~03 UT LANL geosynchronous satellites observed increase in penetrating background due to energetic electrons (G. Hoogeveen and LANL MPA team) Dst recovery begins

• Geosynchronous penetrating background due to energetic electrons peaked on 8 Nov (G. Hoogeveen and LANL MPA team)
• Ongoing ULF wave activity observed in CANOPUS array (G. Rostoker)
• Well developed negative phase ionospheric storm in progress. Storm affects ionosondes at Hobart, Canberra and Mundaring (P. Wilkinson)
• 7 Nov Intermittent IMP-8 data suggest solar wind speeds in excess of 600 km/s ( A. Lazarus)

• IMP-8 emerges into dawnside solar wind, hourly average velocities in excess of 600 km/s recorded
• Ionosondes see ionospheric Storm abate (P. Wilkinson)

• Dst recovered to prestorm values
• Polar Cap index declined to quiet
• Ap recovered to prestorm values

Back to Event Study Home Page

Please send any comments or additional information to Guan Le .

Last modified: September 6, 1995 .