Ground-based ELF/VLF arrays for wave-particle interactions
Transcript of Ground-based ELF/VLF arrays for wave-particle interactions
Ground-based ELF/VLF arrays
for wave-particle interactions
Maria SpasojevicRBSP SWG
21 Aug 2012
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
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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
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
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Longitude [deg]
Latit
ude
[deg
]
PA
RS
FZ
P2
WD
L = 4
L = 5
L� ��
L = 10
Palmer Average Spectrum 2000-2010
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
ELF/VLF Viewing Area
16 UT
ELF/VLF Viewing Area
18 UT
ELF/VLF Viewing Area
20 UT
ELF/VLF Viewing Area
22 UT
Statistical Prediction of In-situ Amplitude Using Ground Obs
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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
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
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)
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
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
Ground-based ELF/VLF arraysfor wave-particle interactions
Maria SpasojevicRBSP SWG21 Aug 2012
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