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Ground-based ELF/VLF arrays for wave-particle interactions

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Ground-based ELF/VLF arrays for wave-particle interactions Maria Spasojevic RBSP SWG 21 Aug 2012
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Page 1: Ground-based ELF/VLF arrays for wave-particle interactions

Ground-based ELF/VLF arrays

for wave-particle interactions

Maria SpasojevicRBSP SWG

21 Aug 2012

Page 2: Ground-based ELF/VLF arrays for wave-particle interactions

Alaska ELF/VLF Receiver Array

AWESOME ELF/VLF

Receivers

Cohen et al., [2010], Harriman

et al, [2010]

Broadband ELF/VLF

� 300 Hz - 45 kHz

� recordes continuously,3-6 days of storage

��Z`UVW[PJ������TPU��ZH]LK����JYVZZLK�SVVW�HU[LUUHZ�

:LUZP[P]P[`

180 190 200 210 220 230 24050

55

60

65

70

75

Longitude [deg]

Latit

ude

[deg

]

TO

KOJU

CH

PF

KNL = 4

L = 5

L = 7

L = 10

Page 3: Ground-based ELF/VLF arrays for wave-particle interactions

Antarctic ELF/VLF Receivers

Palmer Station

81 m2 antenna

10 yr database of spec-trally categorized chorus and hiss emissions[Golden et al.], 2011

200 230 260 290 320 350

�

�

�

�

�

�

Longitude [deg]

Latit

ude

[deg

]

PA

RS

FZ

P2

WD

L = 4

L = 5

L� ��

L = 10

Palmer Average Spectrum 2000-2010

Page 4: Ground-based ELF/VLF arrays for wave-particle interactions

ELF/VLF Viewing Area

500 km circle at 100 km mapped out the eq. plane

14 UTAnalysis of Palmer station data (L=2.5) shows that emissions are primarily non-ducted [Golden et al., 2010]

Inward cross-L magnetospheric propa-gation allows Palmer to monitor higher-L

Page 5: Ground-based ELF/VLF arrays for wave-particle interactions

ELF/VLF Viewing Area

16 UT

Page 6: Ground-based ELF/VLF arrays for wave-particle interactions

ELF/VLF Viewing Area

18 UT

Page 7: Ground-based ELF/VLF arrays for wave-particle interactions

ELF/VLF Viewing Area

20 UT

Page 8: Ground-based ELF/VLF arrays for wave-particle interactions

ELF/VLF Viewing Area

22 UT

Page 9: Ground-based ELF/VLF arrays for wave-particle interactions

Statistical Prediction of In-situ Amplitude Using Ground Obs

��Golden et al.�������\ZLK�HU�H\[VYLNYLZZP]L��T\S[PWSL�YLNYLZZPVU�TVKLS�[V�WYLKPJ[�PU�ZP[\�OPZZ�HTWSP[\KLZ�IHZLK�VU�[OL�VJJ\YYLUJL�VM�^H]LZ�H[�7HSTLY�Z[H[PVU

��7YLKPJ[P]L�JHWHIPSP[`�MHPYS`�^LHR��PU�ZP[\�OPZZ�HTWSP[\KLZ�HYL��_�OPNOLY�^OLU�OPZZ�PZ�VIZLY]LK�H[�7HSTLY�VU�[OL�K\ZRZPKL�

��;/,40:�VIZLY]H[PVUZ�HYL�MYVT�ZVSHY�TPU�^OLU�ZPNUPMPJHU[S`�ML^LY�LTPZZPVUZ�HYL�VIZLY]LK�VU�[OL�NYV\UK

Page 10: Ground-based ELF/VLF arrays for wave-particle interactions

Narrowband VLF Recordings

Demodulated amplitude and phase of VLF transmitters (20-30 kHz) is recorded continuously at each station

170 180 190 200 210 220 230 240 25040

45

50

55

60

65

70

75

80

85

Longitude [deg]

Latit

ude

[deg

]

NLK

TO

KO JU

CHPF

KN

L = 2

L = 3

L = 4

L = 5

L = 7

L = 10

Page 11: Ground-based ELF/VLF arrays for wave-particle interactions

VLF Remote Sensing

Ambient Ionosphere

~85km

t 2

t 1

VLF ReceiverVLF Transmitter

Disturbance

Ȉ�modes

Electron Density [cmí3

]

Alt

itu

de

[km

]

10í3

10í1

101

50

60

70

80

t

am

bient ionosp

here

Dis

turb

ance

0 1 20

20

40

60

80

100

Alt

itu

de [

km

]

Energy Deposition [eV/km x104]

30 keV

100 keV

300 keV

1 MeV

Reflection

Height

Energy Deposition per Particle

Track the amplitude and phase of a VLF transmitter signal as a function of time

Changes in ionospheric density profile along the path results in amplitude and phase changes in the observed signal

Array of receivers to determine the spatial extent of disturbance. Forward modeling to estimate the precipitation fluxes

Page 12: Ground-based ELF/VLF arrays for wave-particle interactions

Lightning Induced Electron Precipitation

NAA-PK

HAIL Data for 28-Mar-2001

NAA-LV

20 NAU-LT

NAU-CS

7:09:00 7:10:00 7:11:00

47

49

46

48

25

30

35

15

20

28

30

42

44

Am

pli

tude [

dB

]

NAU-PK

NAU-WA

NAU-LV

Perturbed Unperturbed

Map of HAIL VLF Signal Paths

[UT]

BD

LT

CS

WA

LV

To NA

U

PK

L=2

L=3 NAA

Lightning

Location

VLF Remote Sensing has been used extensively to quantify electron precipitation due to non-ducted lightning (PhD theses of Lauben, Johnson, Bortnik, Peter, Cotts)

Chorus-driven electron precipitation has also been detected using VLF remote sensing

Tricky because chorus generation can result in precipitation of 5-50 keV electrons, and propagation to higher latitudes can scatter >1MeV electrons

Recovery signatures can be used to determine energy range of precipitation:Rodger et al., 2007 (>2 MeV) and Golkowski and Inan, 2008 (<50 keV)

Page 13: Ground-based ELF/VLF arrays for wave-particle interactions

EMIC Driven Particle Precipitation

FUV proton aurora mapped to the SM-eq plane using T04s

GOES-10 observes, LANL1991-080 proxy predicts EMIC waves

0 1 20

20

40

60

80

100

Alt

itude [

km

]

Energy Deposition [eV/km x104]

30 keV

100 keV

300 keV

1 MeV

VLF Reflection

Height

Energy Deposition per Particle

EMIC-driven precipitating protons deposit energy >100 km altitude

EMIC-driven >MeV electron pre-cipitation deposits energy below the VLF reflection height

Page 14: Ground-based ELF/VLF arrays for wave-particle interactions

Detect MeV Electron Precipitation?

170 180 190 200 210 220 230 240 25040

45

50

55

60

65

70

75

80

85

Longitude [deg]

Latit

ude

[deg

]

NLK

TO

KOJU

CHPF

KN

L = 2

L = 3

L = 4

L = 5

L = 7

L = 10

{{

Auroral

precipitation

EMIC-driven

precipitation

Page 15: Ground-based ELF/VLF arrays for wave-particle interactions

Ground-based ELF/VLF arraysfor wave-particle interactions

Maria SpasojevicRBSP SWG21 Aug 2012

Page 16: Ground-based ELF/VLF arrays for wave-particle interactions

VLF Remote Sensing Limited to Darkness

c

19:5

8 U

T

EUV

log

Col

. Den

sity

, cmï

0

1

FUV

Brig

htne

ss, k

R

10

11

��

d

detachedarc

PDSV�WR�S·SDXVH

FUV Ionosphere FUV Mapped to Eq Plane EUV Plasmasphere


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