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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
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