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M AGNETOSPHERE -I ONOSPHERE C OUPLING M ORE I S D IFFERENT. William Lotko, Dartmouth College. System perspective  qualitative differences Life cycle of an ionospheric O + plasma element Creation & Evolution Transport & Fate Impacts Reconciling models with measurements.

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slide1

MAGNETOSPHERE-IONOSPHERE COUPLING

MORE IS DIFFERENT

William Lotko, Dartmouth College

  • System perspective  qualitative differences
  • Life cycle of an ionospheric O+ plasma element
    • Creation & Evolution
    • Transport & Fate
    • Impacts
  • Reconciling models with measurements
slide2

1730 UT

30º Lat

20 Nov 2003

Foster et al. ‘05

slide3

1820 UT

30º Lat

20 Nov 2003

Foster et al. ‘05

slide4

1945 UT

CUSP

POLAR WIND

Downward J||

BPS

Downward J||

30º Lat

20 Nov 2003

Foster et al. ‘05

slide5

CUSP

Midlatitude plume

+

Electron precipitation

+

Alfvénic Poynting flux

O+ outflow

30º Lat

cf. Strangeway et al. ‘05

Zheng et al. ‘05

slide6

1945 UT

BPS

30º Lat

20 Nov 2003

Foster et al. ‘05

slide7

Auroral BPS

  • Patch/Plume Dynamics
  • Convects across CRB
  • Upward Vi const
  • before, during, after
  • The enhancement produces massive
  • upflux as it drifts
  • through the Boundary Plasma Sheet region.

Semeter et al. ‘03

slide8

Auroral BPS

Alfvénic Poynting Fluxes

Statistical Distributions

Keiling et al. ‘03

Polar satellite data

slide9

Auroral BPS

  • Intense Alfvén waves
  • Superthermal electrons
  • Ion  heating
  • Massive outflows
  • How is the Alfvénic power converted to ion heat?
    • ICRH
    • BBELF
    • coherent energization
    • stochastic energization

What regulates the outflow mass flux?

Chaston et al. ‘03

slide10

Auroral BPS

Outflow in other auroral-zone regions

Paschmann et al. ‘03

slide11

1945 UT

Downward J||

Downward J||

30º Lat

20 Nov 2003

Foster et al. ‘05

slide12

Downward Currents

  • BBELF turbulence
  • Superthermal electrons
  • Filamentary J||
  • Ion  heating
  • Downward E||
  •  “pressure cooker”
  • Large outflows, but limited
  • by downward E||

Lynch et al. ‘02

slide14

Auroral Electrodynamics

Opgenoorth et al. ‘02

slide15

Alfvén Wave Intensification

Feedback Instability in the

Ionospheric Alfvén Resonator

equator

J||

ENS

8.25

L = 7.25

ionosphere

t = 0 s

-5 A/m2

  • Conditions
    • Low-conductivity E region
    • Large-scale downward J||
    • Large-scale intense E
    • Strong  gradient in P
  • Effects
    • Reduced Joule dissipation
    • Filamentary J||
    • 1-10 km -scale turbulence
    • Enhanced outflow
    • Superthermal, bidirectional e

31 s

62 s

93 s

637 mV/m

124 s

-36 A/m2

Streltsov and Lotko ‘04

slide17

Simulated Time Variation of Ne Profile in Downward Current Region

Cavity formation on bottomside is more

efficient than at F-region peak

 Bottomside gradient steepens

Doe et al. ‘95

slide18

FATE

  • Plasmasheet
  • Normally H+ dominant
  • O+-rich during storms
    • O+ injections from

Cusp fountain

Nightside BPS

  • Stormtime substorms
  • H+ is swept away
  • Leaving O+ dominant

pressure and density

  • Earthward injected O+

dominates ring current

Kistler et al. ‘05

slide19

FATE

Ring Current & Plasma Sheet Composition

Nose et al. ‘05

slide20

IMPACT

Simulated O+/H+ Outflow into Magnetosphere

Winglee et al. ‘02

slide21

Feedback

Instability

IAR

Modes

1 min

1-10 s

< 10 km

Ion Outflow ~ 10 min

Patch

Dynamics

Bottomside

Depletion

10 s

Cavity

Formation