Stormtime Dynamics of the Magnetosphere
near Geosynchronous Altitudes
William J. Burke1, Meg A. Noah2 and Jun Yang2
4 November 2014
1. Boston College/ISR
2. University of Massachusetts, Lowell
Stormtime near Geosynchronous Altitudes
Abstract
This presentation offers a tentative synthesis of inner-magnetospheric dynamics during
magnetic storms gained over more than 40+ years starting with the launch of Explorer 45.
During this mission the ring current’s “nose structure,” the dynamics of the zero-energy Alfvén
boundary and their inter-connectedness were first identified. About 20 years later the CRRES
satellite was launched into a geostationary transfer orbit with a sensor payload that monitored the
variability of electric fields and keV ions and electrons in the ring current and inner plasma sheet.
CRRES latter provided the first detections of penetration, shielded and over-shielded electric fields,
severe inflation of the stormtime magnetosphere and glimpses of ion-conics reaching the equatorial
plane. In the early 1990s Los Alamos National Laboratory (LANL) investigators first identified a
stormtime phenomenon they called “sawtooth events” (STEs) that occur almost simultaneously
at all local times. We show that STEs: (1) mostly they occur during the main phases of storms in
a relatively small range of Dst indices, (2) reflect massive decreases in magnetotail open flux and
consequent plasmoid ejections , and (3) cannot occur during magnetic super storms. The Van Allen
Probe mission consists of two identical spacecraft that were launched into CRRES-like orbits in
August 2012. A major advance over CRRES-era sensors is their monitoring mass compositions
as well as energy and pitch-angle ion distributions. We consider the dynamical properties flux
of O+ ion conic distributions observed during the 1 June 2013 storm’s main phase.
Stormtimes near Geosynchronous Altitudes
Outline
Presentation has four parts:
• A brief review of 10 background concepts
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
Magnetic Storm Phases
The Dessler-Parker-Sckopke relation
The Burton-Russell-McPherron equation
Plasma sheet configurations during substorms
Cross polar cap potential (PC)
Ring-current nose structure
Zero-energy Alfvén boundary (ZEAB)
Saw tooth Events (STE)
Magnetospheric inflation
Ion beams and conics
• Case-study analysis of a magnetic storm with STEs
• Whys and wherefores of the STE climatology
• Case-study analysis O+ ion conic injections during a magnetic storm
Stormtimes near Geosynchronous Altitudes
Background Reminders
1. Magnetic Storm Phases
SSC
Main
50
Sym H (nT)
4. Plasma Sheet Configurations
during Substorms
0
Initial
-50
-100
Recovery
-150
151:12
152:00
152:12
Day: UT 2013
153:00
153:12
2. Dessler-Parker-Sckopke Relation
Dst *  DB  2W B0 / 3Wm
Wm  8  1017 J
3. Burton-Russell-McPherron Equation
dDst *
Dst *
  EI 
dt

Hones, E. J. (1984 ), Plasma sheet behavior during substorms,
in Magnetic Reconnection in Space and Laboratory Plasmas,
AGU Monograph 30, 178-184.
Stormtime near Geosynchronous Altitude
(5) Cross Polar Cap Potential PC
Heppner-Maynard Pattern
E  B   B
V

2
B
B2
• Cold ionospheric plasma drifts along
equipotential lines.
• Faraday’s equation
B
t


E  dl    B  dA    M
t
t
 E  

With a stormtime PC of 100 kV,
in 10 s crosses the red line from
the day towards the night side.
PC is a measure of the rate at which
magnetic flux M in Webers moves
from the day to the night side across
a line connecting the maximum and
minimum potential.
Stormtime near Geosynchronous Altitude
Lessons from Explorer 45 => S3 Satellite:
(7) ZEAB
(6) Ring current
nose-structure
Ejiri, M. (1978), Trajectory traces of
charged particles in the magnetosphere,
J. Geophys. Res., 83, 4798-4810.
Smith, P. H., and R. A. Hoffman (1974), Direct observations in the dusk hours
of the characteristics of the storm time ring current particles during the beginning
of magnetic storms, J. Geophys. Res., 79, 966-971.
Stormtimes near Geosynchronous Altitudes
(8) Sawtooth Structures (STEs)
Example from 18 April 2002
Schematic representation
T = full period
Ts = stretching phase
Td = dipolarization phase
Example of STEs observed “simultaneously” by 5 LANL satellites
distributed in local time around geosynchronous
Stormtimes near Geosynchronous Altitude
(9) Magnetospheric Inflation during Superstorms
CRRES discovery during June 1991 storm
6 April 2000
31 March 2001
Tsyganenko, N. A., H. J. Singer, and J. C. Kasper (2003), Storm-time distortion
of the inner magnetosphere: How severe can it get?, J. Geophys. Res., 108(A5),
1209, doi:10.1029/2002JA009808.
Stormtimes near Geosynchronous Altitude
(10) Ion Beams and Conics
Parallel acceleration
Perpendicular heating
• gyro-resonant wave-article interactions
• Upward push by magnetic gradient force
• Role of downward E|| => “pressure cooker effect”
Retterer, J. M. et al. (1987), Monte Carlo modeling
of ionospheric oxygen acceleration by cyclotron
resonance with broadband electrostatic turbulence,
Phys. Rev Lett. 59, 148-151
Stormtime near Geosynchronous Altitude
Lessons from CRRES:
We considered two manifestations
of low energy ions detected by the
LEPA sensor on CRRES.
• During times of minor disturbance
LEPA detected both field-aligned
and omni-directional. Identified as
signatures of conics and S/C
charging events.
• During the 24 March 1991 storm
CRRES detected sporadic fieldaligned ion fluxes coming from both
ionospheres, but not simultaneously.
Rubin, A. G., W. J. Burke, and D. A. Hardy (1995), Low-energy ion spectral peaks
detected by CRRES in the plasma sheet, J. Geophys. Res., 100, 19,22-19,226.
Stormtimes near Geosynchronous Altitudes
Lessons from CRRES: 24 March 1991 Storm
Huang, C. Y., W. J. Burke, and C. S. Lin (2005), Ion precipitation in the dawn sector
during geomagnetic storms, J. Geophys. Res., 110, A11213, doi:10.1029/2005JA011116.
Stormtimes near Geosynchronous Altitude
Lessons from LANL/GOES
Latitude – longitude distribution of LANL and GOES spacecraft
in relation to the magnetic equator
Stormtimes near Geosynchronous Altitudes
Lessons from LANL/GOES: March 2002 Storm
Stormtimes near Geosynchronous Altitudes
Lessons from LANL/GOES: March 2002 Storm
near time of the first STE
• LANL-01A near local midnight
• Both GOES satellites on dayside
Stormtimes near Geosynchronous Altitude
Lessons from LANL/GOES: March 2002 Storm
near times of the second, third and fourth STEs
• GOES s/c on nightside observed
three stretching- dipolarization
sequences near times of STE onsets.
• Night/day onset difference at time
of STE3 (C) versus (A)
• Reflects gradient-curvature drift
of ~ 10 minute delay time.
• E  B drifts way too slow
• Two pseudo breakup events marked
by green triangles
Stormtimes near Geosynchronous Altitude
Lessons from LANL/GOES: March 2002 Storm
Observed interplanetary drivers
and geomagnetic responses raise
two questions:
(a) How does one reconcile Sym-H
behavior after STE onsets with
requirements of D-P-S relation?
(b) Are STEs directly driven by
variations in the solar wind
or IMF?
Stormtimes near Geosynchronous Altitudes
Lessons from LANL/GOES: March 2002 Storm
Tests of hypotheses that STEs
are directly driven by:
• Solar wind pressure pulses
• Northward turnings of IMF BZ
• Conclusion: not supported by
LANL / ACE data comparison.
• Chaosong Huang’s “critical open
magnetic flux” hypothesis.
Stormtimes near Geosynchronous Altitudes
Lessons from LANL/GOES: March 2002 Storm
2
For a magnetic dipole

ˆ
B(R E ,θ) = -B0 [2Cosθ rˆ + Sinθ θ]
The open magnetic flux threading
the polar cap is
RE
25
2.5
20
2
15
1.5
10
1
0.5
5
0
0
 PC ( PC ) 
PC

B  dA  4 R B0
2
E
0
PC

0
C os  Sin d  2 RE2 B0 Sin 2 PC
0
The corresponding polar cap area is
APC (PC )  2 RE2
PC

0
Sin d  2 RE2 (1  Cos PC )
5
10
15
Colatitude
20
25
Open Flux (G-Wb)
Polar Cap Area (M-km )
Tests of Chaosong Huang’s hypothesis: STEs can only occur after the quantity
of open flux in the lobes of the magnetotail exceeds a critical level near 1 GWb
Stormtimes near Geosynchronous Altitudes
Lessons from LANL/GOES: March 2002 Storm
Estimated APC using EUV data from the IMAGE satellite
• Highly elliptical orbit of IMAGE allows it to view northern high latitudes
for about 8 consecutive hours.
• Distinguish auroral oval (strong emissions) from polar cap (strong emissions)
• Optical data show APC rising above 1.7 106 km2 (dash line) before STE onsets
then quickly falling below this level.
Stormtimes near Geosynchronous Altitudes
STE Climatology
• Studied 535 storm, 111 STE sequences
• 438 individual “teeth”
• 1998 – 2007
• 6 (5.4%) outside storms
• < T > = 179.6  54 min
• Required:
• Two or more “teeth”
• At midnight and noon  3 hr LT
Magnetic Storm Categories
Weak:
Dst min > -50 nT
Moderate: -50  Dst min > -100 nT
Intense:
-100  Dst min > -250 nT
Super
Dst min > -250 nT
Cai, X., J.‐C. Zhang, C. R. Clauer, and M. W. Liemohn (2011), Relationship
between sawtooth events and magnetic storms, J. Geophys. Res., 116, A07208,
doi:10.1029/2010JA016310.
Stormtimes near Geosynchronous Altitudes
Three critical observations from Cai et al. (2011):
• Generally isolated substorms that occur outside of storm periods produce
clear ion-injection signatures on the nightside but weak to no flux changes
on the dayside disruption.
• Often during storms that occur after long periods of geomagnetic quiet the
first “tooth” in an STE sequence looks like effects of a isolated substorm.
• Clear STE signatures often absent in electron* fluxes and low energy
(< 60 keV) ions.
Methodology:
• Cai et al only listed storms in which they found events that met their criteria.
• We developed our own list of 1998 – 2007 storms and examined all storms
with special concentration on those NOT listed as manifesting STEs.
Stormtimes near Geosynchronous Altitudes
SW
P (nPa)
Sym-H (nT) PC (kV) BY BZ (nT)
SW
-3
800
40
700
30
600
20
500
10
400
0
20
300
V (km/s)
50
SW
N (cm )
STE Climatology
10
0
-10
-20
300
200
100
0
0
-20
-40
-60
-80
-100
272:00
272:12
273:00
273:12
274:00
Non-storm STEs on 29 – 30 September 2001reported by Cai et al. (2011)
Stormtime near Geosynchronous Altitude
STE Climatology
50
Sym-H
0
-50
-100
-150
-200
112:00
112:06
112:12
112:18
113:00
149:00
149:06
149:12
149:18
150:00
Examples of a missed STEs (left) and a case in which the dayside
magnetopause crossed geostationary altitudes (right).
Stormtime near Geosynchronous Altitude
700
40
600
SW
SW
50
30
-3
500
20
400
SW
10
Interplanetary drivers and
geomagnetic responses on
6 - 7 April 2002.
300
0
30
20
10
0
-10
-20
-30
250
• PC and Sym-Hmin
approached
200
~ 220 kV and -330 nT
150
PC
 (kV)
Y
Z
B B (nT)
V (km/s)
N (cm ) P (nPa)
STE Climatology: The April 2000 Superstorm
100
50
~ 5 s to transfer 1M Wb
from the dayside into
the polar cap
0
Sym-H (nT)
100
0
-100
-200
-300
-400
97:00
97:12
98:00
98:12
99:00
Huang, C. Y., and W. J. Burke, Transient sheets of field-aligned current observed
by DMSP during the main phase of a magnetic storm, J. Geophys. Res., 109,
A06303, doi: 10.1029/ 2003JA010067, 2004.
Stormtimes near Geosynchronous Altitude
SW
800
30
700
20
600
10
500
0
400
SW
-3
SW
40
V (km/s)
N (cm ) P (NPa)
STE Climatology: The November 2003 Superstorm
Interplanetary drivers and
geomagnetic responses on
20 November 2003.
• PC and Sym-Hmin
25
Y
Z
B B (nT)
50
0
-25
-50
approached
PC
 (kV)
300
200
~ 250 kV and -500 nT
100
0
~ 4 s to transfer 1M Wb
from the dayside into
the polar cap
Sym-H (nT)
100
0
-100
-200
-300
-400
-500
324:00
324:06
324:12
324:18
325:00
Stormtimes near Geosynchronous Altitudes
April 2000 Superstorm
Sym-H (nT)
100
0
-100
-200
-300
-400
97:00:00
97:12:00
98:00:00
98:12:00
No evidence of a main phase injection event
99:00:00
Stormtimes near Geosynchronous Altitude
SW
800
30
700
20
600
10
500
0
400
SW
-3
SW
40
V (km/s)
N (cm ) P (NPa)
STE Climatology: The November 2003 Superstorm
Interplanetary drivers and
geomagnetic responses on
20 November 2003.
• PC and Sym-Hmin
25
Y
Z
B B (nT)
50
0
-25
-50
approached
PC
 (kV)
300
200
~ 250 kV and -500 nT
100
0
~ 4 s to transfer 1M Wb
from the dayside into
the polar cap
Sym-H (nT)
100
0
-100
-200
-300
-400
-500
324:00
324:06
324:12
324:18
325:00
Stormtimes near Geosynchronous Altitude
SW
800
30
700
20
600
10
500
0
400
SW
-3
SW
40
V (km/s)
N (cm ) P (NPa)
STE Climatology: The November 2003 Superstorm
Interplanetary drivers and
geomagnetic responses on
20 November 2003.
• PC and Sym-Hmin
25
Y
Z
B B (nT)
50
0
-25
-50
approached
PC
 (kV)
300
200
~ 250 kV and -500 nT
100
0
~ 4 s to transfer 1M Wb
from the dayside into
the polar cap
Sym-H (nT)
100
0
-100
-200
-300
-400
-500
324:00
324:06
324:12
324:18
325:00
Stormtimes near Geosynchronous Altitudes
20 November 2003 Superstorm
Sym-H (nT)
100
0
-100
-200
-300
-400
-500
324:00
324:06
324:12
324:18
325:00
Stormtimes near Geosynchronous Altitude
SW
800
30
700
20
600
10
500
0
400
SW
-3
SW
40
V (km/s)
N (cm ) P (NPa)
STE Climatology: November 2003 Superstorm
Interplanetary drivers and
geomagnetic responses on
20 November 2003.
• PC and Sym-Hmin
25
Y
Z
B B (nT)
50
0
-25
-50
approached
PC
 (kV)
300
200
~ 250 kV and -500 nT
100
0
~ 4 s to transfer 1M Wb
from the dayside into
the polar cap
Sym-H (nT)
100
0
-100
-200
-300
-400
-500
324:00
324:06
324:12
324:18
325:00
Sym-H (nT)
100
0
-100
-200
-300
-400
97:00:00
97:12:00
98:00:00
98:12:00
Figure 4. Energetic proton fluxes measured by geosynchronous
satellites 1991-080 (top), LANL-97A (2nd), 1994-084 (3rd), and
1989-046 on 6 - 7 April 2006. Traces in the in the 6th panel
show inclination angles inferred from measurements by magnetometers on GOES 8 (purple) and GOES 10 (green). The Sym-H
trace is repeated in the bottom panel for reference.
99:00:00
Sym-H (nT)
100
0
-100
-200
-300
-400
-500
324:00
324:06
324:12
324:18
Figure 6. Energetic proton fluxes measured by the geosynchronous satellites
1991-080 (top), LANL-97A (2nd), 1994-084 (3rd), and 1989-046 on 20 November
(DOY 324) 2003. Traces in the in the 6th panel give inclination angles inferred
from measurements by magnetometers on GOES 10 (purple) and GOES 12 (yellow).
The Sym-H index is repeated in the bottom panel for reference.
325:00
Stormtimes near Geosynchronous Altitudes
O+ Ion Conics
Lessons from the Van Allen Probes: 1 June 2013 Storm
30
800
(a)
700
-3
400
0
300
km/s)
500
10
SW
600
20
V
NSW (cm ) PSW (nPa)
40
Interplanetary drivers and responses
of geomagnetic indices.
(nT)
20
BZ
30
0
10
(b)
• Since VAP launch 6 storms with Dstmin < 90 nT.
• Ion conics seen on 3 with nightside apogee.
• No signatures detected on dayside
BY
-10
-20
AU AL (nT)
-30
2000
1000
(c)
• Nsw increase and SSC occur ~16:30 UT 31 May
0
-1000
• Southward / northward turnings near 01:40
and 07:37 UT on 1 June
-2000
Sym H (nT)
50
0
• Bottom panels show AU (red) , AL (blue) and
Sym-H (black) indices
-50
-100
-150
(d)
151:12
152:00
152:12
Day: UT 2013
153:00
153:12
Stormtime near Geosynchronous Altitude
Nose
Structure
Van Allen Probes: 1 June 2013 Storm
Energy (eV)
ZEAB
UT
L
MLT
VAP-B: O+
10
6
10
5
104
103
VAP-A: O+
10
6
10
5
104
103
VAP-A: p+
108
107
10
610
5104
VAP-A: e-
1098
10
107
10
610
5104
01:00
3.33
18.79
02:00
4.86
20.32
03:00
5.80
21.29
04:00
6.27
22.04
05:00
6.24
22.75
06:00
6.20
23.54
• Apogee near 21.1 MLT with
VAP-B leading by ~ 19 min.
• Nose structure near L = 4 in
O+ and p + fluxes
• ZEAB crossed near 01:50 UT,
marked by transition between
photo- and plasma sheet electron
dominance.
• Quasi-periodic structuring of
< 2 keV O + fluxes detected from
02:00 to 06:00 UT
• VAP A & B traces appear similar
but they are not identical
Stormtime near Geosynchronous Altitude
Lessons from the Van Allen Probes: 1 June 2013 Storm
1 2 34
80    110
160    180
UT 02:00
L
4.86
MLT 20.32
03:00
5.80
21.29
04:00
6.27
22.04
05:00
6.24
22.75
06:00
6.20
23.54
• Pitch-angle distributions of < 2 keV O+ ions are nonisotropic and originate in northern ionosphere.
• Associated with substorm expansion recovery cycles.
• Similar histories when VAP A & Bin are close spatial
proximity.
O+ Energy (eV)
1
06
1
05
1
04
VAP-A
VAP-B
1000
AU AL (nT)
7
500
0
-500
-1000
-1500
-2000
0.4
0.2
0
E
O+ Energy (eV)
0    20
8
1
D L (R ) D MLT (hrs)
10
5 6 7
-0.2
-0.4
02:00
03:00
04:00
05:00
06:00
Stormtimes near Geosynchronous Altitudes
Lessons from the Van Allen Probes: 1 June 2013 Storm
DMSP F18
06
50 60 70 80
18
Ions
Electrons
00
BXsat
Bysat
BZsat
12
Mapping of VAP-A trajectory to northern
ionosphere (red) at 1 hour intervals and
compared with equatorward boundary
of auroral electron precipitation sampled by
DMSP F18 (yellow) and F 16 (green).
02:59
UT
MLat 41.0
MLT 19.6
03:02
49.9
19.4
03:05
58.70
19.0
03:08
67.0
18.3
03:11
74.0
17.1
• Fluxes of down-coming electrons
and ions with 30 eV < E < 30 keV.
• B components in S/C coordinates
Stormtimes near Geosynchronous Altitude
Lessons from the Van Allen Probes: 1 June 2013 Storm
j (A / m2)
20
N
0
||
E
10
Y’
-20
BZ’
1000
800
(nT)
600
Z
B
Z’
-10
400
200
0
3:04
(1) Magnetic perturbation:
 BZ 
3:05
3:06
 BYsat  193   BZsat  37 
2
(2) Rotation angle:
  cos1  BZsat  37  /  BZ 
(3) Ampère’s law:
j|| 
3:07
3:08
2
d BZ
1  BZ
1
  B  



0
0 Y
0 Vsat  Cos dt
1
3:09
Stormtimes near Geosynchronous Altitudes
Summary and Conclusions:
• The reported studies concentrated on the phenomenology and causality of
STEs and the presence of O+ ions in the ring.
• The hypothesis of Chaosong Huang that large quantities of magnetic
flux occurs during STE events was confirmed.
• This is consistent with anomalous behavior found in Sym-H traces
near the times of STEs indicating that large plasmoids were ejected from
the magnetosphere.
• Inflation of the inner magnetosphere by the ring current during
superstorms is consistent with the absence of substorm triggering.
• VAP detections of O+ ion conic signatures during the main phase of
magnetic storms provides a plausible explanation of O+ presence in the
nose structure of the ring current.