A characteristics of ionosphere D-region using tweek radio atmospherics at Malaysia

This paper presents an observation of tweek radio atmospherics received at Malaysia (UKM station) from 21
^st
to 25
^th
October 2010 and 1
^st
to 5
^th
November 2010 from 12:00:00 UT to 00:00:00 UT (Universal Time); 08:00 pm to 08:00 am. Fundamental cut-off frequency (f
_cm
) will be extracted from tweeks spectrograms to measure the night-time D-region ionospheric reflection height (h), night-time D-region equivalent electron density (n
_e
) and propagation distance (d) traveled by VLF waves from the causative lightning discharges to the receiving station. Analysis of 10 days sample that involves 2518 tweeks demonstrates that these ELF/VLF signals travel considerable distances up to 7500 km from the causative lightning discharges. The estimated ionosphere reflection height varies from 85 km to 92 km and the estimated equivalent electron density at the reflection height varies from 22 el/cm
³
to 24 el/cm
³
.