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
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Characteristics of VLF Tweeks
Nedra Tounsi & Hassen Ghalila
Laboratoire de Spectroscopie Atomique Moléculaire et Applications
Ionosphere
Earth-Ionosphere Waveguide
Earth
Ligthning - Sprites : Electrical source of electromagnetic waves
The waveguide acts as a filter -> remains only the waveguide modes
Zoom
Zoom
Cutoff frequency
Velocity dispersion
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
Height
=>
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
(Ohya 2003)
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
(1)
For perfectly conducting boundary layers of Earth- ionosphere waveguide,the equation reduice to expression (2).
(2)
00:05:21,1279426
Long:16.290300
Lat : 44.363000
Coupling of AtmosphericLayers:projectconcernsthanderstorms,electrical And space radiation effects in the stratosphere, mesosphere and lowerthermosphere.
www.blitzortung.org
Storms in centrale Europe
∆t = t record - t CAL
∆t = 3,05 ms
D=C. ∆t
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
(www.movable-type.co.uk/scripts/latlong.html)
N
1.3°
O
E
S
Identification of the lightning
=arctan (BEW/BNS )
Twochannel orthogonal Magneticloopantenna configuration.
=1.3°
Thank you