Magnetosphere  -­‐Ionosphere  Coupling  Effects  at  Mid  La8tudes  

John  Foster,  Philip  Erickson,  Anthea  Coster  

MIT  Haystack  Observatory  USA  

Auroral J ~ Σ E

Processes  in  the  Plasmasphere  Boundary  Layer  couple  the  magnetospheric  ring  current  to  the  underlying  ionosphere  

   Farley-­‐Buneman  instability  driven  by  SAPS  electric  field      Field-­‐aligned  currents  closing  through  the  ionosphere  drive  ionospheric  irregulari8es  

   Enhanced  Radar  Backsca7er    Radio  propaga8on  characteris8cs  accumulate  natural  and  ar8ficial  wave  energy  in  the  inner  magnetosphere  with  related  effects  at  ionospheric  and  magnetospheric  al8tudes  

   Rela8vis8c  par8cle  accelera8on  and  losses    Penetra8on  electric  field  upliK  the  mid-­‐la8tude  ionosphere  

   Increased  TEC  and  F-­‐region  instabili8es    Ion  hea8ng  and  ouLlow,  wave  mode  conversion,  parametric  instabili8es  

   Ionospheric  source  of  magnetosphereic  plasmas      Magne8sphere-­‐Ionosphere  coupling  

   

Plasmasphere  &  Ring  Current  

RBSP  crossing  plasmasphere,  plume,  SAPS  channel,  ring  current  at    20  MLT  

Magne

8c  Aligne

d  E  Field  (m

V/m)  

PBL:  Geospace  Plume  (SED)  SAPSS  Electric  Field  Ring  Current  

SAPS  

Plume  

-20

-15

-10

-5

0

5

10

E-mg

sesp

infit

vxb-s

ubco

rotati

ng-fra

memV

/m

Ey

Ez

-15

-10

-5

0

5

10

E-fie

ldFA

CE-

dot-B

-not-u

sed

corot

ating

-frame

mV/m

Azimuthal East

Radial Outward

-15

-10

-5

0

5

10

15

E-fie

ldFA

CE-

dot-B

-whe

re-OK

corot

ating

-frame

mV/m

Azimuthal East

Radial Outward

1530 1600 1630

-0.50.00.51.01.5

E-do

t-Bfla

g

NO E-dot-B

OK E-dot-B

hhmm2015 Mar 17

Tue O

ct 13

18:48

:24 20

15

Van  Allen  Probes  

L  ~  3  

Meridional  sec8on  of  power  flux  predicted  by  AFRL’s  VLF  Propaga8on  Code  in  the  plasmasphere  due  to  NPM  transmissions.  The  transmi^er  is  marked  by  a  triangle.  Note  the  prominent  shadow  boundary  in  the  conjugate  hemisphere.  An  analogous  boundary  (not  visible)  exists  in  the  transmi^er  hemisphere.          [Starks  et  al,  2009]  

Propaga8on  of  VLF  Waves    in  Inner  Magnetosphere  

 The  VLF  Bubble  

Freq

uency  (kHz

)  

Dipole  L  

Storm  Time  Erosion  of  the  Plasmasphere  

 Effects  of  PBL  at  Mid  La8tudes  

Whistler  Chorus:  WPI  at  PBL  Density  Gradient  

[Foster  &  Rosenberg,  1976]  

EXTENDING TO PLASMASHEET

Disturbed  Ring  Current  drives  MagneHc  Field-­‐

Aligned  Currents  into  the  Sub-­‐Auroral  Ionosphere  

REGION 2

REGION 1

(Slide  courtesy  D.  Mitchell)  

Plasmasheet  Electrons  

SAPS  Electric  Field  

Earthward  FAC  

KineHc  AcceleraHon  of  Plasmasphere  Ions  

Enhanced  Radar  Backsca^er  (ERB)  from  Topside  F  Region  (Destabiliza8on  of  Ion  Acous8c  Waves  at  PBL)  

[Foster  et  al.,  GRL,  1988]  

Evidence  for  ERB  associated  with    

F-­‐Region  Current  Closure  across  SAPS  Channel  

   

(Millstone  Hill  Azimuth  Scan)  

[Foster  ,  1988]  

SAPS  

PBL:  SAPS  &  Ionospheric  Trough  

Ionospheric Conductance is Low in the Trough

Auroral Ionosphere

Mid-Latitude Ionosphere

Ionospheric Trough

J ~ Σ E

EP

RII RI

SAR  (Stable  Auroral  Red)  Arcs  

Millstone  Hill  Radar  ObservaHons  

SAR  

SAPS  DMSP  

Op8cs  

WPI:    Radia8on  Belt  Modifica8on    

(Courtesy:    D.  Summers  &  D.  Baker)  

Van  Allen  Probes  Plasma  Waves:  VLF  Chorus  

Electron  Accelera8on  Sequence  in  the  Inner  Magnetosphere  

Source: 10’s of keV (MMS/EPD) Seed: 100’s of keV (VAP/MagEIS) Rad Belt: > 1 MeV (VAP/REPT)

Jaynes  et  al.  [JGR,  2015]  

Waves,  Par8cles,  M-­‐I  Coupling  

Local  Accelera8on  of  Ultra-­‐Rela8vis8c  Radia8on  Belts