Jamjareegulgarn, Punyawi

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Jamjareegulgarn, Punyawi
Alternative Name
Jamjareegulgarn, P.
Main Affiliation
Email
punyawi.ja@kmitl.ac.th

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    Assessment of improvement of the IRI model for foF2 variability over three latitudes in different hemispheres during low and high solar activities
    (2021-03-01)
    Timoçin, Erdinç
    ;
    Temuçin, Hüseyin
    ;
    Inyurt, Samed
    ;
    Shah, Munawar
    ;
    Jamjareegulgarn, Punyawi
    This paper discusses the diurnal and seasonal variations of the F2 layer critical frequency (foF2) and the improvement of performance of the IRI-2016 model in predicting foF2 over three latitudes in different hemispheres during low and high solar activities. We extracted the foF2 data from six ionosonde stations which are Manila (14.7<sup>o</sup>N, 121.1<sup>o</sup>E), Yamagawa (31.2<sup>o</sup>N, 130.6<sup>o</sup>E), Yakutsk (62.0<sup>o</sup>N,129.6<sup>o</sup>E), Townsville (19.6<sup>o</sup>S, 146.8<sup>o</sup>E), Hobart (42.9<sup>o</sup>S, 147.3<sup>o</sup>E) and Terre Adelie (66.6<sup>o</sup>S, 140.0<sup>o</sup>E). The data of both low solar activity (LSA) period and high solar activity (HSA) periods were divided into three seasons as Northern Summer (May, June, July and August), Equinoxes (March, April, September and October) and Northern Winter (November, December, January and February). The present study showed that the IRI-2016 performance is strongly dependent on the solar activity, latitude, season, local time and hemisphere. For both hemispheres, the foF2 values at low latitude station are larger than those at middle latitude station, whereas the foF2 values at middle latitude station are larger than those at high latitude station. The agreement between IRI2016-modelled foF2 and foF2 measurements on all stations selected in the northern hemisphere is best for North Summer and worst for North Winter. For northern hemisphere, the values of relative deviations during both solar activities are largest in high latitudes and smallest in middle latitudes. As for southern hemisphere, the values of relative deviations during LSA are largest in middle latitudes and smallest in high latitudes, whereas the values of relative deviations during HSA are largest in low latitudes and smallest in high latitudes. It is thought that the relative deviations in the observed foF2 values are caused by solar activity that strongly alter chemical and electromagnetic processes in the ionosphere. These results are important for future improvements depending on solar activity and seasons in the IRI model for foF2 values over three latitudes in different hemispheres.
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    Exploring Electromagnetic Wave Propagation Through the Ionosphere Over Seismic Active Zones
    (2025-03-01)
    Eshkuvatov, Husan
    ;
    Ahmedov, Bobomurat
    ;
    Shah, Munawar
    ;
    Begmatova, Dilfuza
    ;
    Jamjareegulgarn, Punyawi
    This study presents an analytical solution for the electric current formation in the lower ionosphere as a result of charged aerosols being ejected from the ground before the earthquakes. The impact of ionosphere-related processes on radio wave propagation through the atmosphere is explored by investigating the resulting energy losses of electromagnetic waves traversing this ionospheric layer. Theoretical considerations suggest that these processes may generate detectable electromagnetic signals, offering insights into seismic precursors. The effects of electron density inhomogeneities in the upper ionospheric layers on electromagnetic wave properties such as group delay, Faraday rotation, and Doppler frequency shift are examined. Understanding these effects aims to improve ionospheric monitoring techniques to detect pre-earthquake disturbances. To validate the theoretical findings, a comparison is made with the empirical data from various sources, including VLF transmitters and GPS-TEC measurements. This comparative analysis underscores the potential of electromagnetic phenomena as credible indicators of impending seismic events.
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    Possible atmospheric-ionospheric precursors of the 2020 Hotan China earthquake from various satellites
    (2024-10-01)
    Hameed, Amna
    ;
    Shah, Munawar
    ;
    Ghaffar, Bushra
    ;
    Riaz, Salma
    ;
    Jamjareegulgarn, Punyawi
    The earthquake (EQ) precursors from satellites data portray an image of the energy propagation from the lithosphere to atmosphere and then to the ionosphere. Previous studies have often presented detailed discussion on different precursors at various altitudes. However, this study aimed to investigate the anomalies at various altitudes associated with the Hotan China EQ (hypocentral depth: 10 km, latitude 35.5°N, longitude 82.4°E). The goal was to identify pre-and post-seismic anomalies statistically in the conjunction with the wavelet transformation. We observed possible precursors in the atmosphere such as variations in aerosol optical depth, tropopause pressure, relative humidity, latent heat flux, and outgoing longwave radiation in a window of 5–10 days before the seismic event. Moreover, the total electron content had precursors during quiet geomagnetic storm conditions (−20 < Dst ≤ − 40 nT, Kp ≤ 3) beyond the bound within 5–10 days. These findings highlight the potential of using atmospheric and ionospheric parameters to detect seismic anomalies as EQ precursors for improved EQ early warning systems.