Investigation of the morphology and Wait’s parameter variations of the low-latitude D region ionosphere using the multiple harmonics of tweeks

Tan, Le Minh

doi:10.1016/j.asr.2016.03.030

Cited by 4 publications

(2 citation statements)

References 24 publications

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“…Electron precipitation was found during a strong magnetic storm [Ohya et al, 2011]. On some nights, the low-latitude D region electron density enhancement could be caused by the quasi-static electric field emitted by strong lightning discharges [Tan, 2016].…”

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confidence: 99%

Electron density variability of nighttime D region ionosphere in Vietnamese and Japanese sectors

et al. 2017

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Recording tweek atmospherics on geomagnetically quiet days in 2014 at Tay Nguyen University (TNU) (12.65°N, 108.02°E), Vietnam, and at Kagoshima (KAG) (31.48°N, 130.72°E), Japan, we investigated the nighttime electron density variability of the D region ionosphere between the equatorial‐low‐latitude Vietnamese and the low‐ to middle‐latitude Japanese sectors. We estimated the reflection height and electron density of the D region ionosphere using the first‐order mode cutoff frequency of tweek atmospherics. The results observed at both stations show that the mean electron density at the reflection height during winter season was higher than that during summer and equinox seasons. The electron density observed at TNU gradually decreased from 20:15 to 4:15 LT from winter to equinox and to summer. The electron density observed at KAG increased from 20:20 to 4:20 LT during summer and winter seasons. The mean electron density during 2014 observed at TNU (25.0 cm−3) was higher by 2.1 cm−3 than that observed at KAG (22.9 cm−3). During 2014, the nighttime electron density variations show a moderate positive correlation with the sunspot number but show weak to no correlation with the galactic cosmic rays. We suggest that the seasonal variations in the nighttime electron density could be significantly caused by the enhancement of geocoronal hydrogen Lyman α intensity and seasonal variation of nitric oxide density in the lower ionosphere.

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Section: Discussionmentioning

confidence: 99%

Electron density variability of nighttime D region ionosphere in Vietnamese and Japanese sectors

et al. 2017

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“…Ionospheric reflection heights, propagation distances and relevant electron densities can be derived from the frequency-time characteristics of tweeks. This method has therefore been used in several case studies to investigate the morphology of the nighttime (Kumar et al, 2008;Maurya et al, 2012;Ohya et al, 2003;Tan, 2016) and exceptionally also the daytime (Ohya et al, 2015;Santolík & Kolmašová, 2017) D-region of the ionosphere.…”

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Automatic Detection of Atmospherics and Tweek Atmospherics in Radio Spectrograms Based on a Deep Learning Approach

Maslej-Krešňáková

Kundrát

Mackovjak

et al. 2021

Earth and Space Science

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Lightning strikes can be routinely observed by the radio receivers that measure electromagnetic signals in the very low frequency range. The acquired pulses called atmospherics provide valuable details about source lightning discharges and also about the Earth‐ionosphere waveguide where they can propagate thousands of kilometers. The automatic acquisition of the events requires also automatic methods for extraction of atmospherics' details to confirm the observed trends with statistical significance. For this purpose, we have developed a method based on a deep learning approach to automatically obtain the type of atmospherics, their exact time, and the frequency range from the frequency‐time spectrograms. The method that employs convolutional neural networks is designed to be adaptable to scientific needs and provide reliable results according to the requirements on the sensitivity to events, computation performance, and precision of extracted details. The efficiency and specific steps of our method are demonstrated for data recorded by the ELMAVAN‐G instrument. The comprehensive description of the method allows its usage for regular characterization of the ionospheric D‐layer or for other similar applications in the future.

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Estimation of nighttime ionospheric D-region parameters using tweek atmospherics observed for the first time in the North African region

Ammar

Ghalila

2020

Advances in Space Research

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Investigation of the morphology and Wait’s parameter variations of the low-latitude D region ionosphere using the multiple harmonics of tweeks

Cited by 4 publications

References 24 publications

Electron density variability of nighttime D region ionosphere in Vietnamese and Japanese sectors

Electron density variability of nighttime D region ionosphere in Vietnamese and Japanese sectors

Automatic Detection of Atmospherics and Tweek Atmospherics in Radio Spectrograms Based on a Deep Learning Approach

Estimation of nighttime ionospheric D-region parameters using tweek atmospherics observed for the first time in the North African region

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