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1
P. Schellart
Probing atmospheric electric fields in thunderstorms through radio emission
from air showers
Gia Trinh
LOFAR Cosmic Ray KSP & Cosmic Lightning Project O. Scholten, S. Buitink, A. Corstanje, J.E. Enriquez, H. Falcke ,J.R. Hörandel, A. Nelles, J. P. Rachen, L. Rossetto, P. Schellart , S. Thoudam, S. ter Veen, A. M. van den Berg, U. Ebert, C. Köhn , C. Rutjes
LOFAR Science Workshop, Assen, June 2nd - 3rd, 2015
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Fair weather vs thunderstorm 2
S. Buitink S. Buitink
Intensity footprint
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Fair weather vs thunderstorm 3
P. Schellart et al. (PRL 114, 165001)
P. Schellart et al. (PRL 114, 165001)
Polarization footprint
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𝐸𝐸 = 𝐸𝐸// + 𝐸𝐸⊥
Transverse-current component Amplitude: ++ Polarization: direction changes
Charge-excess component Amplitude: 0/+ Polarization: more radial
𝑬𝑬⊥
𝑬𝑬//
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Effective atmospheric electric fields
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kvi - center for advanced radiation technology
B
v
𝑬𝑬⊥𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃
𝒉𝒉𝒂𝒂𝒃𝒃𝒃𝒃𝒂𝒂𝒃𝒃
𝒉𝒉𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃
𝒉𝒉
𝑬𝑬⊥ 0
𝐸𝐸⊥𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏 = 𝑘𝑘𝐸𝐸⊥𝑎𝑎𝑏𝑏𝑏𝑏𝑎𝑎𝑏𝑏
𝑬𝑬⊥𝒂𝒂𝒃𝒃𝒃𝒃𝒂𝒂𝒃𝒃
5
A two-layer model of E-fields
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B
v
𝑬𝑬⊥𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃
𝒉𝒉𝒂𝒂𝒃𝒃𝒃𝒃𝒂𝒂𝒃𝒃
𝒉𝒉𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃
𝒉𝒉
𝑬𝑬⊥ 0
𝐸𝐸⊥𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏 = 𝑘𝑘𝐸𝐸⊥𝑎𝑎𝑏𝑏𝑏𝑏𝑎𝑎𝑏𝑏
𝑬𝑬⊥𝒂𝒂𝒃𝒃𝒃𝒃𝒂𝒂𝒃𝒃
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A two-layer model of E-fields Why two layers?
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𝒉𝒉𝒂𝒂𝒃𝒃𝒃𝒃𝒂𝒂𝒃𝒃
𝒉𝒉𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃
𝒉𝒉
𝑬𝑬⊥ 0
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𝒉𝒉𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃
𝒉𝒉
𝑬𝑬⊥ 0
𝒉𝒉𝒂𝒂𝒃𝒃𝒃𝒃𝒂𝒂𝒃𝒃
𝒉𝒉𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃
𝒉𝒉
𝑬𝑬⊥ 0
8
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𝒉𝒉𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃
𝒉𝒉
𝑬𝑬⊥ 0
𝒉𝒉𝒂𝒂𝒃𝒃𝒃𝒃𝒂𝒂𝒃𝒃
𝒉𝒉𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃
𝒉𝒉
𝑬𝑬⊥ 0
𝒉𝒉𝒂𝒂𝒃𝒃𝒃𝒃𝒂𝒂𝒃𝒃
𝒉𝒉𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃
𝒉𝒉
𝑬𝑬⊥ 0
+ =
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𝒉𝒉𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃
𝒉𝒉
𝑬𝑬⊥ 0
𝒉𝒉𝒂𝒂𝒃𝒃𝒃𝒃𝒂𝒂𝒃𝒃
𝒉𝒉𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃
𝒉𝒉
𝑬𝑬⊥ 0
𝒉𝒉𝒂𝒂𝒃𝒃𝒃𝒃𝒂𝒂𝒃𝒃
𝒉𝒉𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃
𝒉𝒉
𝑬𝑬⊥ 0
+ =
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Two-layer E-fields ↔ ring structure
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Direction of E-fields: determined from polarization patterns
𝑬𝑬⊥𝒂𝒂𝒃𝒃𝒃𝒃𝒂𝒂𝒃𝒃
𝑬𝑬⊥𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃
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A reconstructed thunderstorm event
P. Schellart et al. (PRL 114, 165001)
P. Schellart et al. (PRL 114, 165001)
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kvi - center for advanced radiation technology
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𝒉𝒉𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃𝒃 and k are well-defined.
𝒌𝒌 hbelow (km)
𝝌𝝌𝟐𝟐
𝑿𝑿𝒎𝒎𝒂𝒂𝒎𝒎 (𝒈𝒈/𝒄𝒄𝒎𝒎𝟐𝟐)
P. Schellart et al. (PRL 114, 165001)
𝝌𝝌𝟐𝟐 mapping
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kvi - center for advanced radiation technology
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Probing effective electric fields
M. Stolzenburg et al., Geophys. Res. Lett. 34 (2007) L04804
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1x10-19 1.05x10-19 1.2x10-19
Parallel electric fields
At 30 – 80 MHz: little sensitivity to parallel electric fields
E∥ = 50 kV/m E∥ = 100 kV/m No E-field
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Parallel electric fields
Enhanced electrons at large distances
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Sensitivity at lower frequencies (2 – 9 MHz) 1.4x10-20 1.8x10-20 3.3x10-20
Parallel electric fields
Suggestion: install some low-frequency antennas
𝐸𝐸∥ = 50 kV/m 𝐸𝐸∥ = 100 kV/m No E-field
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Summary and outlook 18
Summary: - Understand the influence of electric fields on air showers and
their radio emission - Build a simple model reconstructing thunderstorm events
successfully - Probe electric fields in thunderstorm using LOFAR Outlook: - Analyze more thunderstorm events in progress
Probing Atmospheric Electric Fields in Thunderstorms through Radio Emission from Cosmic-Ray-Induced Air Showers, P. Schellart, T.N.G. Trinh et al., Phys. Rev. Lett. 114, 165001 Influence of Atmospheric Electric Fields on Radio Emission from Cosmic-Ray Induced Air Showers (in preparation)
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Thank you!
