Characteristics of VLF Tweeks . In this spectrogram recorded by our receiver during August 2007 we can recognize the tweeks characteristics which present tails with the sferics. Magnetic Field variation. Nedra Tounsi & Hassen Ghalila
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Nedra Tounsi & Hassen Ghalila
Laboratoire de Spectroscopie Atomique Moléculaire et Applications
Ligthning - Sprites : Electrical source of electromagnetic waves
The waveguide acts as a filter -> remains only the waveguide modes
ZoomDetection of tweeks
The two first tails are clear enough to extract the cutoff frequencies and the dispersion of the light velocity
f2 =2f1 ; f3=3f1 ; f4=4f1
Ionospheric height , Group velocity
Group velocity =>
Vg =c[1-(fc /f)2]1 /2
σe=qe Ne µe
µe =1.36N0/ Nn
Ne (h)=1.241.10-8 FC Fh
Fh =B e/2πm (Cyclotron frequencies)
Fh =1.2294 MHz
∆t = t1 - t2
Time interval between two close frequencies gives the source distance of atmospherics which is written as expression (1).
∆t = d/vg1 - d/vg2
For perfectly conducting boundary layers of Earth- ionosphere waveguide,the equation reduice to expression (2).
Lat : 44.363000Validation with CAL data
Coupling of AtmosphericLayers:projectconcernsthanderstorms,electrical And space radiation effects in the stratosphere, mesosphere and lowerthermosphere.
Storms in centrale Europe
∆t = t record - t CAL
∆t = 3,05 ms
00 :05 :21.131
D = 916 km
The storms which took place in
Bosnia seem to be responsible for these tweeks
(Long,Lat) D = 1084 km from Tunis
Identification of the lightning
=arctan (BEW/BNS )
Twochannel orthogonal Magneticloopantenna configuration.