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What can we learn/predict from global MHD models? Seth G. Claudepierre, The Aerospace Corporation Contributors: Mary Hudson, Bill Lotko, Scot Elkington, Mike Wiltberger, Richard Denton, John Lyon, Frank Toffoletto, Asher Pembroke, Kazue Takahashi
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What can we learn/predict from global MHD models?

Feb 04, 2022

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Page 1: What can we learn/predict from global MHD models?

What can we learn/predict from global MHD models?

Seth G. Claudepierre, The Aerospace Corporation

Contributors: Mary Hudson, Bill Lotko, Scot Elkington, Mike Wiltberger, Richard Denton, John Lyon, Frank Toffoletto, Asher Pembroke, Kazue Takahashi

Page 2: What can we learn/predict from global MHD models?

What can we learn from global MHD models?

“The source of the oscillations driving field line resonances(FLRs) in the magnetosphere remains controversial.” – Stephenson and Walker, AG, [2010].

Individual solar wind parameters can be isolated in global MHD simulations to asses their role in the generation of magnetospheric ULF waves (externally driven, Pc4-5 waves).

Page 3: What can we learn/predict from global MHD models?

Kelvin-Helmholtz Instability Driven Dynamic Pressure Driven

SW SW

→ Numerical experiments with a global MHD simulation

(Claudepierre et al., JGR, 2008) (Claudepierre et al., JGR, 2010)

ULF Pulsations and the Solar Wind

Page 4: What can we learn/predict from global MHD models?

Kelvin-Helmholtz Instability Driven Dynamic Pressure Driven

SW SW

(Claudepierre et al., JGR, 2008) (Claudepierre et al., JGR, 2010)

ULF Pulsations and the Solar Wind

Page 5: What can we learn/predict from global MHD models?

Dynamic Pressure Simulations

SW

• Four LFM simulations: (3) monochromatic ULF frequencies (10, 15, 25 mHz): (1) continuum of ULF frequencies (0-30 mHz): • All other input parameters the same: n0 = 5 particles/cm3 B = (0, 0, +5) nT Vx = 600 km/s Vy = Vz = 0 km/s Cs out of phase (→ Pth ~ nCs

2 = const )

)sin()( 0 tCntn ω+=

∑ ++=j

jjtDntn )sin()( 0 ξω

Solar Wind Driving

)~( 2vnpdyn

Page 6: What can we learn/predict from global MHD models?

Monochromatic and Continuum Simulation

∑ ++=j

jjtDntn )sin()( 0 ξω

Solar Wind Driving

)sin()( 0 tCntn ω+=

)~( 2vnpdyn

Page 7: What can we learn/predict from global MHD models?

10 mHz Simulation EL Wave Power, Equatorial Plane

2/1

),()(

)],([FFT),(

=

=

∫b

a

f

f

L

dffxPxRIP

txEfxP

[fa, fb] = [9.5,10.5] mHz

*Claudepierre et al., JGR, 2010

Xgsm

Ygsm RIP EL [mV/m]

Page 8: What can we learn/predict from global MHD models?

10 mHz Simulation EL Wave Power, 15 MLT Meridional Plane

*Claudepierre et al., JGR, 2010 Rgsm

Zgsm

15 MLT

2/1

),()(

)],([FFT),(

=

=

∫b

a

f

f

L

dffxPxRIP

txEfxP

[fa, fb] = [9.5,10.5] mHz RIP EL [mV/m]

Page 9: What can we learn/predict from global MHD models?

10 mHz Simulation Bφ Wave Power, 15 MLT Meridional Plane

*Claudepierre et al., JGR, 2010

2/1

),()(

)],([FFT),(

=

=

∫b

a

f

fdffxPxRIP

txBfxP

ϕ

[fa, fb] = [9.5,10.5] mHz

Rgsm

Zgsm

15 MLT

RIP Bφ [nT]

Page 10: What can we learn/predict from global MHD models?

10 mHz Simulation Bφ Wave Power, 15 MLT Meridional Plane

*Claudepierre et al., JGR, 2010 Rgsm

Zgsm

15 MLT

RIP Bφ [nT]

Q: What is the natural oscillation frequency of the white field line?

Page 11: What can we learn/predict from global MHD models?

10 mHz Simulation Bφ Wave Power, 15 MLT Meridional Plane

*Claudepierre et al., JGR, 2010 Rgsm

Zgsm

15 MLT

RIP Bφ [nT]

Q: What is the natural oscillation frequency of the white field line? A: 1

)(2

= ∫

N

SA

n sVdsnf (WKB)

Page 12: What can we learn/predict from global MHD models?

10 mHz Simulation Bφ Wave Power, 15 MLT Meridional Plane

*Claudepierre et al., JGR, 2010 Rgsm

Zgsm

15 MLT

RIP Bφ [nT]

Q: What is the natural oscillation frequency of the white field line? A:

mHz 10)(

2

1

1

=

∫f

sVdsnf

N

SA

n (WKB)

Page 13: What can we learn/predict from global MHD models?

10 mHz Simulation EL, Spectral Density, 15 MLT Meridian

*Claudepierre et al., JGR, 2010

1

)(2

= ∫

N

S An sV

dsnf (WKB)

RIP EL [mV/m]

RIP EL [mV/m]

XY-plane

15 MLT-plane

Page 14: What can we learn/predict from global MHD models?

10 mHz Simulation EL, Bφ Field-Aligned Mode Structure

*Claudepierre et al., JGR, 2010

RIP EL [mV/m]

RIP Bφ [nT]

15 MLT-plane

15 MLT-plane

Page 15: What can we learn/predict from global MHD models?

Continuum Simulation Results

*Claudepierre et al., JGR, 2010 w

ave

pow

er, P

dyn

1

)(2

= ∫

N

SA

n sVdsnf (WKB)

Page 16: What can we learn/predict from global MHD models?

LFM (no plasmasphere) MP

Claudepierre et al., JGR, 2010 Er wave power 15 MLT

Page 17: What can we learn/predict from global MHD models?

LFM (no plasmasphere) Er (FLR) Eφ (WG)

MP MP

Er wave power 15 MLT

EΦ wave power 15 MLT

Page 18: What can we learn/predict from global MHD models?

LFM (no plasmasphere) Er (FLR) Eφ (WG) Bz (WG)

MP MP MP

Page 19: What can we learn/predict from global MHD models?

LFM

(no

plas

mas

pher

e)

LFM

-RCM

(w/ p

lasm

asph

ere)

Er (FLR) Eφ (WG) Bz (WG)

MP MP MP

MP PP

Page 20: What can we learn/predict from global MHD models?

LFM

(no

plas

mas

pher

e)

LFM

-RCM

(w/ p

lasm

asph

ere)

Er (FLR) Eφ (WG) Bz (WG)

MP MP MP

MP MP PP PP

Page 21: What can we learn/predict from global MHD models?

LFM

(no

plas

mas

pher

e)

LFM

-RCM

(w/ p

lasm

asph

ere)

Er (FLR) Eφ (WG) Bz (WG)

MP MP MP

MP MP MP PP PP PP

Page 22: What can we learn/predict from global MHD models?

LFM-RCM (w/ plasmasphere)

Eφ (WG)

Bz (WG)

MP

MP PP

PP THEMIS Observations (statistical – all data from 2008)

Courtesy of Kazue Takahashi

Page 23: What can we learn/predict from global MHD models?

Figures courtesy of S. Ukhorskiy and D. Sibeck

4-8-12 hrs separation along 24 hour orbit

8-8-8

8-8-8

FS inner sphere Burst: PP, plume, EMIC

FS inner sphere Burst: Plume, EMIC, shock

FS inner sphere

FS plumes Burst: shocks FS, inner sphere waves

FS apogee, inbound Burst: dipolarization

FS inbound Burst: MS, chorus, EMIC

FS pp, outbound, apogee Burst dipol., pp, EMIC

THEMIS/RBSP Conjunction Campaigns

Page 24: What can we learn/predict from global MHD models?

Conclusions

• Solar wind dynamic pressure fluctuations can drive ULF waves on the dayside.

• Solar wind dynamic pressure fluctuations can excite toroidal mode FLRs and

compressional waveguide modes.

• First study of FLRs and waveguide modes using a global MHD model of the

solar wind/magnetosphere interaction.

• Recent work with the LFM-RCM, which includes a static plasmasphere, shows

promise for more detailed simulation/observation comparisons.

• The plasmasphere plays an important role in ULF wave generation in the inner

magnetosphere.