Multi-Fluid/Particle Treatment of MagnetosphericIonospheric Coupling During Substorms and Storms
R. M. Winglee
 Strong Heavy Ion Ionospheric Outflows observed during
active periods
 Substantial Asymmetries that provide key insight during
active periods
 Multi-Fluid Equations ideal substorm
• Particle acceleration associated with boundary layers
• Magnetic reconnection & current sheet acceleration
• Influence of heavy ions on the global dynamics
 Application to the Storm of April 17, 2003
Yau and Andre, 1997
Speiser, 1965
Iijima and Potemra,
1978
R2
R1
R1
R2
Dawn-Dusk
Merging of
FieldAligned
Currents
Systems
Ideal MHD Current: Anti-symmetric
Ogino, 1986
Multi-Fluid Equations

dV
 q n ( E  V  B )  P
dt
Ideal MHD
Neglect all cyclotron terms
E  Ve  B  0
Accurate treat of system
if its is in pressure
balance
Ve  Vi
No Parallel Electric Fields
No Ion Differentiation
No Current Sheet Acceleration
(aka Speiser motion)
Multi-Fluid Equations

dV
 q n ( E  V  B )  P
dt
More Accurate Solution
d Ve  gyro
dt
E  Ve  gyro  B 
 Ve  gyro 
0
1
B
(Pe  Pe
)0
ene
B
E  B Pe  B
B  B


kT
e
B2
ene B 2
eB3
For the Ions

dV
 q n ( E  V  B)  P
dt
J  e(
n
i
 V i  - n e  V e )
i
dVi
B
i
 J  B  Pi  (Pe  Pe
)  eni ( Vi 
dt
B

i
ni  Vi 
)B
ne
Not Zero
Polar
(Thermal)
Winds
Gravity
Fixed Ionospheric Density and
Temperature; Zero Velocity
, T, V determine by
magnetospheric driving and
ionospheric conditions
Resistive
Earth/Atmos.
Inner Radius
: 2.5 Re
Grid Resolution: 0.25 Re
H+: 400 cm-3, 10 eV eq., 0.1 eV polar
O +: 5%
Zero IMF
Southward IMF
Northward IMF
(-8 nT for 80 min)
(8 nT for 60 min)
3
4.5
3
Current (MA)
2
1
0
-1
2.5
3.5
4
-2
-3
Time (hrs)
5
5.5
T = 0313
12
T = 0337
T = 0410
18
06
00
Current (MA)
2.5
2
1.5
1
0.5
0
2.5
T = 0250
3
3.5
T = 0420
4
12
18
4.5
T = 0430
06
00
5
5.5
1.E+26
Ion Outflow (ions/s)
Protons
Oxygen
1.E+25
1.E+24
1.E+23
2.5
3
3.5
4
4.5
Time (hrs)
5
5.5
1E+26
Outflow (ions/s)
Protons
Oxygen
1E+25
1E+24
1E+23
0
0.5
1
1.5
Auroral Current (MA)
2
2.5
Solar Wind Density
cm-3
1
0.01
20 Re
-50 Re
Ionospheric H+ Density
cm-3
1
0.01
20 Re
-50 Re
Relative Ionospheric O+ Density
%
40
20
10
20 Re
-50 Re
Ionospheric O+ Temperature
20 Re
-50 Re
Cross-Polar Cap Potential
Cross Polar Cap Potential (kV)
80
70
60
50
40
30
20
10
0
2.5
3
3.5
Time (hrs)
4
4.5
5
Effective Plasma Resistivity
(Cross-Polar Cap Potential/Total Ionospheric Current)
0.09
Effective Resistance (Ohms)
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
2.5
3
3.5
Time (hrs)
4
4.5
5
Effective Ohmic Dissipation
(Cross-Polar Cap Potential*Total Ionospheric Current)
Effective Power (GW)
140
120
100
80
60
40
20
0
2.5
3
3.5
4
Time (hrs)
4.5
5
Modification of reconnection
20 Re
-50 Re
Side View
Modification of reconnection
20 Re
-50 Re
Top View
Midnight O+ Ionospheric Outflow
Dawn
Dusk
20 Re
Velocity (1000 km/s)
50 Re
Midnight O+ Ionospheric Outflow
12
18
06
00
Full O+ Ionospheric Outflow
12
18
06
00
M/I Coupling for an Idealized Substorm
 Larger response of heavy ionospheric ions to activity
and increases the effective ionospheric
conductivity
 Midnight light ions and pre-midnight heavy ions have
access to tail reconnection region
 Acceleration leads to locally high concentrations of O+
AND asymmetric tail reconnection
 Ion cyclotron affects lead to the generation of flux
ropes
 The asymmetries lead to distortion of the field-aligned
current system
Apr 17, 2002 Storm
Polar Cap Potential (kV)
350
300
250
200
150
100
50
0
10.5
11
11.5
12
12.5
12
12.5
13
UT
Ion Outflow (ions/s)
1.E+26
Protons
Oxygen
1.E+25
1.E+24
10.5
11
11.5
UT
13
1.E+26
Outflow (ions/s)
Protons
Oxygen
1.E+25
1.E+24
0
2
4
6
Auroral Current (MA)
8
10
Solar Wind Density
Relative O+ Density
Ionospheric H+ Temperature
Equatorial Bz
Positive
Negative
Top View of Magnetic Field lines
Storm Activity
 Northward pressure pulse leads to large entry of
solar wind plasma
 Eventually excluded by ionospheric plasma
 Large IMF swings allow protons not oxygen to
rapidly respond
 Both increases and decreases in effective conductivity
 Large IMF variations also allow both sunward and
tailward motion of the near-Earth neutral line
 Latter part of the even during sustained southward
IMF should allow build up of O+
Ionospheric O+ Density
cm-3
1
0.01
Solar Wind Temperature
Ionospheric H+ Temperature
Duskside O+ Ionospheric Outflow
Dawn
Dusk
16 Re
Velocity (1000 km/s)
55 Re
Duskside O+ Ionospheric Outflow
12
18
06
00
Cusp O+ Ionospheric Outflow
Dawn
Dusk
16 Re
Velocity (1000 km/s)
55 Re
Cusp O+ Ionospheric Outflow
12
18
06
00
Dawn O+ Ionospheric Outflow
Dawn
Dusk
16 Re
Velocity (1000 km/s)
55 Re
Dawn O+ Ionospheric Outflow
12
18
06
00