Russian Journal of Earth Sciences Russian Journal of Earth Sciences Russian Journal of Earth Sciences 1681-1208 48282 10.2205/2023ES000833 ОРИГИНАЛЬНЫЕ СТАТЬИ ORIGINAL ARTICLES ОРИГИНАЛЬНЫЕ СТАТЬИ Variation of Total Electron Content over Nepal during Geomagnetic Storms: GPS Observations Variation of Total Electron Content over Nepal during Geomagnetic Storms: GPS Observations https://orcid.org/0000-0001-6286-2106 Silwal Ashok Silwal Ashok as0432@uah.edu https://orcid.org/0000-0001-7379-4268 Gautam Sujan Prasad Gautam Sujan Prasad Poudel Prakash Poudel Prakash https://orcid.org/0000-0001-5356-2267 Karki Monika Karki Monika https://orcid.org/0000-0001-5012-8721 Chapagain Narayan P Chapagain Narayan P https://orcid.org/0000-0002-2799-9112 Adhikari Binod Adhikari Binod University of Alabama in Huntsville Huntsville США University of Alabama in Huntsville Huntsville United States of America University of Alabama in Huntsville США University of Alabama in Huntsville United States of America Tribhuvan University Непал Tribhuvan University Nepal Tribhuvan University Непал Tribhuvan University Nepal Tribhuvan University Непал Tribhuvan University Nepal Xavier College Непал Xavier College Nepal 23 09 2023 23 09 2023 23 3 1 19 16 01 2022 31 01 2023 https://rjes.ru/en/nauka/article/48282/view

Geomagnetic storms have very profound effects on the Total Electron Content (TEC) of the ionosphere. In order to investigate the equatorial and low-latitude ionospheric response to the geomagnetic storms of varying intensities, a detailed study of vertical TEC (VTEC) variations resulting from Global Positioning System (GPS) data acquired at four GPS stations in Nepal along 80°–90° E longitude and 26°–30° N latitude sector has been carried out in the present work. The results were analyzed with other favorable inducing factors (solar wind parameters and geomagnetic indices) affecting TEC to constrain the causative factor. Positive phases are observed for all the storms studied. During the severe geomagnetic activity, the deviation was ~18 TECU, while it was recorded ~12 TECU and ~8 TECU during moderate and minor geomagnetic activity, respectively. The Detrended Cross-Correlation Analysis (DXA) illustrates that the value of the hourly average VTEC of the BESI station was found to have a strong positive correlation with other stations in all types of storm events, indicating a similar response of all stations towards the space weather events. In addition, the correlation of VTEC with solar wind parameters and geomagnetic indices illustrated that the VTEC shows a strong positive association with solar wind velocity (Vsw) in all three geomagnetic events. In contrast, the correlation of plasma density (Nsw), interplanetary magnetic field (IMF-Bz), the symmetric horizontal component of geomagnetic field (SYM-H), and Geomagnetic Auroral Electrojet (AE) index with VTEC vary with the intensity of the storm. Overall results of the study have revealed the characteristic features of TEC variation over Nepal regions during magnetic storms, which validates earlier research on ionospheric responses to geomagnetic storms and theoretical assumptions.

Geomagnetic storms have very profound effects on the Total Electron Content (TEC) of the ionosphere. In order to investigate the equatorial and low-latitude ionospheric response to the geomagnetic storms of varying intensities, a detailed study of vertical TEC (VTEC) variations resulting from Global Positioning System (GPS) data acquired at four GPS stations in Nepal along 80°–90° E longitude and 26°–30° N latitude sector has been carried out in the present work. The results were analyzed with other favorable inducing factors (solar wind parameters and geomagnetic indices) affecting TEC to constrain the causative factor. Positive phases are observed for all the storms studied. During the severe geomagnetic activity, the deviation was ~18 TECU, while it was recorded ~12 TECU and ~8 TECU during moderate and minor geomagnetic activity, respectively. The Detrended Cross-Correlation Analysis (DXA) illustrates that the value of the hourly average VTEC of the BESI station was found to have a strong positive correlation with other stations in all types of storm events, indicating a similar response of all stations towards the space weather events. In addition, the correlation of VTEC with solar wind parameters and geomagnetic indices illustrated that the VTEC shows a strong positive association with solar wind velocity (Vsw) in all three geomagnetic events. In contrast, the correlation of plasma density (Nsw), interplanetary magnetic field (IMF-Bz), the symmetric horizontal component of geomagnetic field (SYM-H), and Geomagnetic Auroral Electrojet (AE) index with VTEC vary with the intensity of the storm. Overall results of the study have revealed the characteristic features of TEC variation over Nepal regions during magnetic storms, which validates earlier research on ionospheric responses to geomagnetic storms and theoretical assumptions.

 Total Electron Content (TEC) GPS Geomagnetic storm Solar wind parameters Cross-correlation GPS-derived TEC Data used for this study is obtained from the UNAVCO (https://www.unavco.org/), and the data of interplanetary parameters and geomagnetic indices are extracted from NASA websites (http://omniweb.gsfc.nasa.gov/ow_min.html). We want to thank staff members of NASA and UNAVCO for making the data available.

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