multi-fluid/particle treatment of magnetospheric-ionospheric coupling during substorms and storms
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Multi-Fluid/Particle Treatment of Magnetospheric-Ionospheric 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 - PowerPoint PPT PresentationTRANSCRIPT
Multi-Fluid/Particle Treatment of Magnetospheric-Ionospheric 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
Dawn-Dusk Merging of Field-Aligned Currents Systems
R1 R1 R2R2
Ogino, 1986
Ideal MHD Current: Anti-symmetric
Multi-Fluid Equations
Pnqdt
d )( B V E
V
Ideal MHD
0 BVE e
Neglect all cyclotron terms
ie VV
No Current Sheet Acceleration
(aka Speiser motion)
No Parallel Electric Fields
No Ion Differentiation
Accurate treat of system if its is in pressure balance
Multi-Fluid Equations
Pnqdt
d )( B V E
V
More Accurate Solution
0
dt
d gyroeV
0)(1
B
BPP
en eee
gyroe BVE
322B eB
BkT
Ben
Pe
e
ee
BBBE V gyro
For the Ions
Pnqdt
d )( B V E
V
) - ( eeii
i nne VVJ
B V
V B JV
)()(i e
iiiieei
ii n
nen
B
BPPP
dt
d
Not Zero
Inner Radius : 2.5 Re
Grid Resolution: 0.25 Re
Fixed Ionospheric Density and Temperature; Zero Velocity
Resistive
Earth/Atmos.
, T, V determine by magnetospheric driving and ionospheric conditions
Gravity
Polar (Thermal)
Winds
H+: 400 cm-3, 10 eV eq., 0.1 eV polar
O +: 5%
-3
-2
-1
0
1
2
3
2.5 3 3.5 4 4.5 5 5.5
Time (hrs)
Cu
rre
nt
(MA
)Zero IMF
Southward IMF
(-8 nT for 80 min)
Northward IMF
(8 nT for 60 min)
0
0.5
1
1.5
2
2.5
2.5 3 3.5 4 4.5 5 5.5
Cu
rren
t (M
A)
T = 0250
T = 0313
T = 0430
12
00
18 06
T = 0337
12
00
18 06
T = 0420
T = 0410
1.E+23
1.E+24
1.E+25
1.E+26
2.5 3 3.5 4 4.5 5 5.5
Time (hrs)
Ion
Ou
tflo
w (
ion
s/s
)Protons
Oxygen
1E+23
1E+24
1E+25
1E+26
0 0.5 1 1.5 2 2.5
Auroral Current (MA)
Ou
tflo
w (
ion
s/s)
Protons
Oxygen
Solar Wind Density
1
0.01
cm-3
-50 Re20 Re
Ionospheric H+ Density
1
0.01
cm-3
-50 Re20 Re
Relative Ionospheric O+ Density
40
20
%
10
-50 Re20 Re
Ionospheric O+ Temperature
-50 Re20 Re
0
10
20
30
40
50
60
70
80
2.5 3 3.5 4 4.5 5
Time (hrs)
Cro
ss P
ola
r C
ap P
ote
nti
al (
kV)
Cross-Polar Cap Potential
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
2.5 3 3.5 4 4.5 5
Time (hrs)
Eff
ecti
ve R
esis
tan
ce (
Oh
ms)
Effective Plasma Resistivity
(Cross-Polar Cap Potential/Total Ionospheric Current)
0
20
40
60
80
100
120
140
2.5 3 3.5 4 4.5 5
Time (hrs)
Eff
ecti
ve P
ow
er (
GW
)
Effective Ohmic Dissipation
(Cross-Polar Cap Potential*Total Ionospheric Current)
Modification of reconnection
Side View
-50 Re20 Re
Modification of reconnection
Top View
-50 Re20 Re
Midnight O+ Ionospheric Outflow
50 Re20 Re
Dusk
Dawn
Velocity (1000 km/s)
Midnight O+ Ionospheric Outflow12
00
18 06
Full O+ Ionospheric Outflow12
00
18 06
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
M/I Coupling for an Idealized Substorm
Apr 17, 2002 Storm
0
50
100
150
200
250
300
350
10.5 11 11.5 12 12.5 13UT
Po
lar
Ca
p P
ote
nti
al (
kV
)
1.E+24
1.E+25
1.E+26
10.5 11 11.5 12 12.5 13
UT
Ion
Ou
tflo
w (
ion
s/s)
Protons
Oxygen
1.E+24
1.E+25
1.E+26
0 2 4 6 8 10
Auroral Current (MA)
Ou
tflo
w (
ion
s/s)
Protons
Oxygen
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
1
0.01
cm-3
Solar Wind Temperature
Ionospheric H+ Temperature
Duskside O+ Ionospheric Outflow
Velocity (1000 km/s)55 Re16 Re
Dusk
Dawn
Duskside O+ Ionospheric Outflow12
00
18 06
Cusp O+ Ionospheric Outflow
Velocity (1000 km/s)55 Re16 Re
Dusk
Dawn
Cusp O+ Ionospheric Outflow12
00
18 06
Dawn O+ Ionospheric Outflow
55 Re16 Re
Dusk
Dawn
Velocity (1000 km/s)
Dawn O+ Ionospheric Outflow12
00
18 06