Nighttime D-Region Ionospheric Characteristic From Tweek Atmospheric Observed In The Mid Latitude Region

Wan Salwani, Wan Harun (2013) Nighttime D-Region Ionospheric Characteristic From Tweek Atmospheric Observed In The Mid Latitude Region. Project Report. UTeM, Melaka, Malaysia. (Submitted)

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Abstract

Tweek atmospheric is an electromagnetic pulse originating from the return stroke of lightning. The signal is propagate by multiply reflection from boundaries of the natural waveguide formed by the Earth’s surface and the lower boundary of the ionosphere layer with small plasma density (1-100cmˉ³). The majority of this energy is concrete in the range of extremely low frequency (ELF: 3-3000 Hz) and very low frequency (VLF: 3-30 kHz) bands. It is difficult to do the measurements in the DRegion Ionosphere due to the altitude is about 60 km in the daytime and increase up to 95 km in the nighttime. Tweek atmospherics has been used to estimate the nighttime D-region Ionosphere reflection height (h), equivalent electron density (ne) at reflection height and the propagation distance (d) travel by the signal. Then the characteristic of tweek will be compare between different stations in low and mid latitude region, and the finding will be developed using Graphical User Interface (GUI) in MATLAB. The electromagnetic propagation model is used in order to study present the nighttime variation of tweek in this region. This study present the nighttime D-region ionosphere characteristic of tweek observed at USA mid latitude ground station of Juneau (58°23’’00’’N, 134°11’’00’’W) during February 2011 and March 2011. The maximum mode number of tweek found in this study is three. Analysis of 620 tweek demonstrates that these ELF/VLF signals travel considerable distance up to 7000km from the causative lightning discharge. The estimated equivalent electron density at the reflection varies from 22.52 to 30.03 el/cm³. The reflection height is found in the altitude ranged of 70 to 91 km.

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