The Physics of Space Plasmas William J. Burke 31October 2012 University of Massachusetts, Lowell Magnetic Storms.

The Physics of Space Plasmas

William J. Burke31October 2012

University of Massachusetts, Lowell

Magnetic Storms

• Historical background:

- Dessler-Parker-Sckopke - Burton-Russell-McPherron relationships

• Electric fields in the inner magnetosphere: penetration, shielding and over-shielding.

- Single particle approach: the Volland-Stern model

- Fluid/multi-fluid approach: The Rice Convection model

- Two crises: (1) too much shielding (June 1991 storm), and (2) electric field saturation (Bastille Day Storm)

- Tsyganenko: Magnetic inflation and contributors to Dst

- Siscoe-Hill and revised Volland-Stern models

• Love and Gannon: Dst movies

• Transmission line analogy

Magnetic Storms

Lecture 7

Magnetic Storms

Magnetic Storms: a brief history:

• Alexander von Humboldt coined the term “magnetic storm” after watching aurorae and magnetic deflection over Berlin in Dec.21, 1806.

• Richard Carrington: witnesses white light flare August 28, 1859 followed by magnetic storm on the next day: aurorae over Havana.

• Kristin Birkeland: After 1902-1903 campaign distinguished between polar elementary storms (substorms) and equatorial perturbations.

• Sydney Chapman: phases of magnetic storms

• Alex Dessler & Gene Parker: (1959) ERC H at the Earth’s surface.

• Masahisa Sugiura: Dst stations and hourly index to calibrate storms

• Burton et al. (1975): Predict Dst from solar wind/IMF

Magnetic Storms

Stormtime E-fields in Inner Magnetosphere:

• E-fields are the only force that can accelerate charged particles• In general:

• Consider a charge particle with an equatorial pitch angle of 90 in the presence of a dawn-to-dusk electric field E = - .

Since

2

2

F mx

m d dF x mx x x K

dt dt

2( )GV B B

qB

( )E B G G G

dKqE V qE V V qE V q V

dt

2 2

( ) ( )G E

dK B B E BqE V E B V B

dt B B

Magnetic Storms

The Volland-Stern single-particle model:

• Here we use a version of the V-S model formulated by Ejiri, JGR, 83, 4798, 1978.• Consider the electric potential (R, ) in the magnetospheric equatorial plane as a superposition of a co-rotation and “externally imposed” potentials

• The corotation potential . C is a constant determined by boundary conditions and is a fitting parameter whose physical meaning is addressed below.

• We will use both cylindrical (R , and Cartesian (XGSM, Y GSM) coordinates.

•Assume that E is in the dawn-dusk (+ YGSM) direction

30( , ) ( ) ( , ) E

C M

B RR R R CR Sin

R

B0RE2 91 kV

ˆ ˆ

ˆ ˆ

R Cos Sin X

Sin Cos Y

ˆˆ

ˆˆ

RX Cos Sin

Sin CosY

1ˆˆ( , ) ( , )E R r RR R

Magnetic Storms

The Volland-Stern single-particle model:

At some point RS = RE LS along the dusk meridian ( = /2) the inward pointing EC exactly cancels the outward directed EM allowing us to calculate C

310

C M 2ˆˆ ˆE(R, ) E (R) E (R, ) EB R

r CR Sin r CosR

3 30 0

1 1( )E E

S E S

B R B RC

R R L

130 1

( , ) 1E

S

B R RR Sin

R R

1 1302

1 ˆˆE(R, ) 1E

S S

B R R RSin r Cos

R R R

191 1

( , ) 1S

kV LL Sin

L L

Magnetic Storms

The Volland-Stern single-particle model:

At the stagnation point LS the potential is

Since the last closed equipotential touches LS => calculate locus of this potential

1 1

2

1 1 ˆˆE(L, ) 15 1S S

mV L LSin r Cos

m L L L

91 1( , ) 1

2SS

L kVL

191 1 91 1

( , ) 1 1 AA

S A S

LkV kVL Sin

L L L

1

( 1) 0A A

S S

L LSin

L L

LA () LS

12

Cos

3 / 2

2

• LA() gives shape of zero-energy Alfvén boundary (ZEAB)

• Still don’t know what means or how to relate EM to the interplanetary medium.

Magnetic Storms

The Volland-Stern single-particle model:

At the magnetopause on the dawn (LY, 3/2) and dusk (LY, /2) the potentials areapproximately PC/2 and - PC/2, respectively.

Average E across magnetosphere 1 Y

LY 1.5 LX

206

60

9.6

( )X

SW SW

BL

P P nPa

614.4 / ( )Y SWL P nPa

1

( )91( , )

2 2PCY

M YY S

kVLkVL

L L

1

1182

( )S YY PC

L LL kV

( )91( , )

2PC

Y

kVkV LL Sin

L L

1

2

( )91( ) ˆˆ ˆE(L, )2PC

E E Y Y

kVkV LR Sin R Cos

R L R L L

Magnetic Storms

Vasyliunas (1969, 1970)

Rice Convection Model: (Harel et al., JGR 1981)

2

||

2

||

0

1 1

ˆ( )2

ie

e

B pj

B

j

j p Bj

s B B B B

B dsj p B

B B

Magnetic Storms

Main Phase Electric fields and particles measured by CRRES

Magnetic Storms

Magnetic Storms

Electric field and particle boundaries sampled by DMSP F8 and CRRES

Magnetic Storms

Tsyganenko, N. A., H. J. Singer, and J. C. Kasper, Storm-time distortion of the inner magnetosphere: How severe can it get? J. Geophys. Res., 108 (A5), 1209, 2003.

Magnetosphere simulation at 22:00 UT on 6 April 2000

Magnetic Storms

Magnetosphere simulation at 08:00 UT on 31 March 2001

Magnetic Storms

Magnetic Storms

Z

Y

B

B

Siscoe et al. (2002), Hill model of transpolar saturation: Comparisons with MHD simulations, JGR 107, A6, 1025.

Ober et al. (2003) , Testing the Hill model of transpolar potential saturation, JGR, 108, (A12),

Model validation with F13 & F15

Magnetic Storms

Ober et

MRC: ISM Simulations with IMF BZ = -2 and -20 nT

PC = I S / (I + S )

S = PSW 0.33

(nPa) /

I = 0 + G V BT Sin2 (/2)

Magnetic Storms

Love, J. J., and J. L. Gannon (2010), Movie‐maps of low‐latitude magnetic storm disturbance, Space Weather, 8, S06001, doi:10.1029/2009SW000518.

Magnetic Storms

November 2003 storm

Magnetic Storms

Magnetic Storms

Magnetic Storms

Magnetic Storms

Electric field Scaling:

• Kelley et al. (2003), Penetration of the solar wind electric field into the magnetosphere/ionosphere system, GRL., 30(4), 1158. compared electric measured with the Jicamarca ISR fields with the Y component of IEF (VBZ). • Found the electric field in the equatorial ionosphere is one 15th of the electric field in the solar wind

• It seemed useful to compare VS with IEFY

Magnetic Storms

Magnetic Storms

Huang, C. Y. and W. J. Burke (2004) Transient sheets of field aligned currents observed by DMSP during the main phase of a magnetic superstorm, JGR, 109,A06303.

Magnetic Storms

0

0

1/

1 1 1

1

Y Yi Yr Yr Yi

A P

A P

A AR

Z Zi Zr

Yi YiYrAS

Zi Zr Zr

Zr Zi

Zi ZrZ P ARP

Y Yi Yr AS AS A AS

E E E E RE

R

V

B B B

E REEV

B B B

B R B

B BB VR

E E E V R V V

Transmission line model “Measured” Poynting Flux

2 2|| || || ||

0 0

(1 ) (1 )Y Z Y Zi i r

E B E BS R S R S S

Aurorae and High-Latitude Electrodynamics

Region 1 = 106 ARegion 2 = 0 A

Region 1 = 106 ARegion 2 = 3105 A

Nopper and Carovillano, GRL 699, 1978

Wolf, R. A., Effects of Ionospheric Conductivity on Convective Flow of Plasmain the Magnetosphere, JGR, 75, 4677, 1970.