Simulated Response of the Magnetosphere-Ionosphere System Simulated Response of the Magnetosphere-Ionosphere System

to Empirically Regulated Ionospheric Hto Empirically Regulated Ionospheric H++ Outflows Outflows

W Lotko1,2, D Murr1, P Melanson1, J Lyon1,3, M Wiltberger2

1Dartmouth College 2NCAR/HAO 3Boston University

How does H+ outflow influence MI coupling?

– Some prior results

– Empirically regulated outflow in the LFM global model

– Event simulation

– Diagnostics

– Feedback between outflow and electron precipitation

Conclusions

Theory Program

SM11D-08

Observational Statistics(Yau and André 97; Cully et al. 03; Lennartsson et al. 04)

Outflow fluence increases

– at higher altitude

– for southward IMF

– with greater SW PDYN

Outflow energy increases

– at higher altitude

– with greater SW PDYN

1-100 GW / hemisphere required to power the H+ outflow

Polar ions: 15 eV – 33 keV

OutflowwithoutPrecipitation(Winglee et al. 02)

“Polar wind” outflow

Any outflow reduces PC

O+ outflow reduces PC

Causal Driver for Ionospheric Outflow

Empirical results derived from FAST cusp data near 4000-km altitude

Strangeway et al. 05; Zheng et al. 05

OUTFLOW ALGORITHM

GallagherDensityModeln = f(r)

V ||=F ||/n

mW/m2

LFM S||

#/m2-s

Source-Weighted FH||

km/s

VH||

Auroral/Cusp

Outflow

CalibrateFluence

FH||

#/m2-s

EmpiricalFormula

(Strangeway)

Source “Regions”

0 1Minimum

(Fe||/Fe||max, 1)#/m2-s

LFM Fe||

By < 0

Bz variable

Bx 0

PDYN steady

until 04:30

Event Simulation

(CISM “Long Run”)

vx 375 km/s

IMF / SW at 20 RE

H+ outflux at 2.25 RE

Bz,

nT

UT4 Mar 96

DU

SK

DU

SK

N S

North South

Log (Flux, # / m2-s)

9 10 11 12 13

8.5 simulation hours

Average Number Flux

Oct 97 – Mar 98

Polar perigee

9 10 11 12

Log (Flux, # / m2-s)

DUSKDUSK DAWN

Lennartsson et al. 04

2 1025 ions/s 3 1025 ions/s 2-3 1024 ions/sFLUENCE

Where does the ionospheric H+ go?

Control Volume Analysis

Not to scale

Control Volume Analysis

Not to scale

Control Volume Analysis

Not to scale

Control Volume Analysis

Not to scale

Mass AdditionDiagnostics

Mostly the inner magnetosphere

Little persistence in Lobe and PS

Mass addition is regulated by

– IMF Bz

– IMF Variability

Outflow latency is 20 minutes relative to IMF turnings

How does ionospheric H+ outflow influence MI coupling?

– Higher density

– Lower || (and e)

– Less e- energy flux

– Lower

– Less FAC

– Higher PC

MI CouplingDiagnostics

Plasma addition at inner boundary

Joule dissipation unchanged!

Feedback: Precipitation with Outflow

10

P= c

ρε

“Drizzle” Energy

“Beam” Energy

1 20

2

J= c

ρ

εε

“Robinson” Conductivity

e3 2 1 2

P 2

0.85Η P

5Σ =

1 + 16

Σ = 0.45 Σ

εεε

F

Precipitating Electron Flux

exp

e

1 23 0

0

= c ρ

8 - 7 -ε ε

ε

F

Electron Energy

0 =ε ε ε

Ionospheric Outflow

i eE× B, , F F

MHDVariables

P

V

B

MHDVariables

P

V

B

Conclusions

Largest outflows when IMF BZ < 0 and variable

Mass persistence in inner magnetosphere; less in outer regions

H+ outflow increases PC while reducing I||

Joule dissipation relatively unaffected!

FEEDBACK between outflow-induced density enhancements and electron precipitation, conductivity dynamics