Wednesday, August 10, 2005

ELF and VLF measurements in Israel during Eurosprite2005

ELF (Extra Low Frequency, 3-30 Hz) recordings can be used to calculate the polarity of lightning discharges and the charge moments associated to them (the amount of charge lowered to the ground by the discharge, multiplied by the altitude from which it has been removed [Ckm]). The ELF station in Israel is operating continuously; it is recording the vertical component of the electric field (Ez) and the two horizontal magnetic field components (Hx and Hy). The sampling frequency is 250 Hz and the ELF signals are recorded in the 1 to 50 Hz range using GPS timing. The data can be downloaded remotely through a modem connection.

The VLF system (see previous post on the use of VLF signals in sprite research) in the Negev desert is collecting 15 hours of continuous broadband data (0.1-50 kHz) from 20:00 UT to 12:00 UT until 15 September. The data is being recorded on 250 Gb external disks that are exchanged every 10 days. 22Gb of data is collected every day. VLF data will supply both broadband data related to the lightning waveforms, as well as narrowband data related to ionospheric perturbations caused by lightning associated phenomena.

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