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