Browsing by Author "Sunil Kumar Chaurasiya"

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Analysis of GPS-TEC and IRI model over equatorial and EIA stations during solar cycle 24
(Elsevier Ltd, 2023) Sunil Kumar Chaurasiya; Kalpana Patel; Sanjay Kumar; Abhay Kumar Singh
Total Electron Content (TEC) measurements provided by Global Positioning System (GPS) as well as the International Reference Ionosphere – 2016 model (IRI01-Corr, IRI-2001, and NeQuick) model were compared at two Indian GPS stations: equatorial station Bangalore (12.580N, 77.350 E) and equatorial ionization anomaly (EIA) station Lucknow (26.500N, 80.550 E) during the solar cycle 24 extending from 2007 to 2017. The spectral, regression and statistical analysis displays a double-hump shape with counterclockwise hysteresis within TEC. The solar flux along with the TEC showed erratic as well as sluggish trends throughout the increasing period and flat and rapid throughout the decreasing period of the solar cycle 24. The semiannual and winter anomaly is discovered to be a constant feature throughout the solar cycle. The main idea of the current study is to investigate the performance of IRI01-Corr, IRI-2001, and NeQuick TEC in contrast to GPS TEC data throughout solar cycle 24 at the Indian equatorial and EIA stations. The modeled TEC data exhibit almost complete agreement with the measurement highlighting the same trends in the solar cycle as well as semiannual and seasonal changes. However, there are clear biases between the observed and modeled TECs when local time, seasons, as well as solar activity phases are considered. The main findings of this paper are that the NeQuick model generally underestimates noon-time TEC while the IRI-2001 model overestimates the same. The error in estimating noontime TEC from the IRI model using IRI-2001 as a topside at the EIA station is higher (142 %) than that at the equatorial station (42 %). © 2023 COSPAR
Equatorial plasma bubbles for solar maximum & moderate year of the solar cycle 24
(Elsevier Ltd, 2022) Sunil Kumar Chaurasiya; Kalpana Patel; Abhay Kumar Singh
The fluctuations in the electron density of the F-region in the ionosphere as compared to the background electron density are the sign of plasma irregularities which is a well-known phenomenon. They occur during post-sunset hours and degrade ionospheric radio wave communication majorly the navigation signals. To explore the features of equatorial plasma bubbles (EPBs) over the Indian region throughout the solar maximum year 2014 and the solar moderate year 2017, we have examined day and night hours plasma irregularities from Defense Meteorological Satellite Program (DMSP) with spacecraft as F15 with total crossings as 9698. From the total crossings, 1115 crossings were obtained with EPBs degrading the communication and navigation signals. The distribution of EPBs was studied monthly, seasonally, and longitudinally for the solar maximum and moderate years which has given significant results. We have also analyzed the occurrence of EPBs during the geomagnetic storms with Disturbed storm time index (Dst) ≤ -100 nT occurred in the solar maximum and moderate years. We have observed that the regular occurrence of EPBs was there during the initial and main phase but smoothens up in course of the recovery phases of the storm. These results are discussed with those of earlier results and are in good agreement too. The observed inferences will help to improve the telecommunication sector in the Indian region. © 2022 COSPAR
Ionospheric response of St. Patrick’s Day geomagnetic storm over Indian low latitude regions
(Springer Science and Business Media B.V., 2022) Sunil Kumar Chaurasiya; Kalpana Patel; Sanjay Kumar; Abhay Kumar Singh
The current work shows the ionospheric response to an intense geomagnetic storm known as St. Patrick’s Day storm which occurred from 17-22 March 2015 using the ionospheric vertical total electron content data over the low latitude Indian stations. We have tried to study how it has influenced the vertical total electron content at four different low latitude stations: Varanasi (Geographic latitude 25°, 19’ N, longitude 82°, 59’ E), Lucknow (Geographic latitude 26°, 50’ N, longitude 80°, 55’ E), Bangalore (Geographic latitude 12°, 58’ N, longitude 77°, 35’ E), and Hyderabad (Geographic latitude 17°, 23’ N, longitude 78°, 27’ E). Various solar and geomagnetic parameters related to the geomagnetic storm have been analyzed to examine the consequences of geomagnetic storms on vertical total electron content. The analysis has been done on account of a comparison of mean total electron content estimated for geomagnetic quiet days and those during the period of the geomagnetic storm 17-21 March 2015. Analysis of vertical total electron content data during the storm period found a negative storm effect on 18 March during daytime at equatorial ionization anomaly station (Varanasi & Lucknow) and Positive storm effect at equatorial station (Hyderabad and Bangalore) which is in agreement with the results of Fagundes et al. (2015) reported in Brazil region. A strong positive storm effect in the daytime is noticed at EIA stations during 20-21 March which is higher at Lucknow (∼63 TECU) than that at Varanasi (∼37 TECU) whereas equatorial stations Bangalore and Hyderabad were found unaffected. The same results have also been reflected from total electron content data of single PRN 17. These positive and negative ionospheric storm effects observed during the geomagnetic storm have been explained using disturb dynamo electric field, prompt penetration electric field and neutral wind effects. The St. Patrick’s Day storm resulted in a minimum Disturbance Storm Time Index of −234 nT, Auroral Electrojet enhancement of up to 1000 nT, and a maximum enhancement of 33 percent of vertical total electron content (VTEC) values at Bangalore, an equatorial region, in comparison to average quiet days’ VTEC. This is known as the positive storm effect. The cohabitation of the prompt penetration electric field and the long-lasting disturbance dynamo electric field has caused the VTEC to respond favorably throughout the region and disturb dynamo electric field. © 2022, The Author(s), under exclusive licence to Springer Nature B.V.
Total electron content forecasting with neural networks during intense geomagnetic storms of the solar maximum and moderate years of solar cycle 24 in the low latitude Indian region
(Springer Science and Business Media B.V., 2023) Sunil Kumar Chaurasiya; Kalpana Patel; Abhay Kumar Singh
A geomagnetic storm is a brief disruption in the magnetosphere of the Earth that depresses the magnetic field. This activity causes variations in the ionospheric Total Electron Content (TEC) and other physical properties because it is connected to solar coronal mass ejections, coronal holes, or solar flares. A modeling method called a Neural Network (NN) displays nonlinear characteristics which include physical variables. The present research aims to develop a feed-forward back-propagation neural network-based forecasting approach to ionospheric TEC throughout a geomagnetic storm. We have contrasted the TEC gained through neural network estimation (NN TEC), GPS TEC, and NeQuick TEC via the IRI model during four intense geomagnetic storms on June 23, 2015 (Kp index of 8.33 and Dst index −198 nT), December 20, 2015 (Kp index of 6.67 and Dst index −166 nT), May 28, 2017 (Kp index of 7.0 and Dst index −125 nT) and August 26, 2018 (Kp index of 7.67 and Dst index −175 nT) across two Indian stations Bangalore (Geog. latitude 12∘, 58’N, longitude 77∘, 35’E), and Lucknow (Geog. latitude 26∘, 50’N, longitude 80∘, 55’E) and analysis have been made. It is observed that modeled NN TEC values, and GPS TEC values, match well during the entire duration of all the geomagnetic storms at both stations. Whereas, except for the geomagnetic storm beginning phase, NeQuick TEC has been underestimated during the entire event across Bangalore and Lucknow during the selected intense geomagnetic storms. It is noted that Lucknow’s maximum deviation of NN and GPS TEC is higher than Bangalore’s. The greatest correlation coefficient 0.99, was found and shows that the modeled NN TEC values, and GPS TEC values, are in excellent agreement. In order to assess the preciseness of the model’s output, Root Mean Square Error (RMSE) and Mean Absolute Percentage Error (MAPE) values were used to compare the projected TEC relative to the measured GPS-TEC and NeQuick TEC model output. The RMSE value of the NN model is shown to be lower throughout the storm’s initial and final phases, but greater throughout its main phase. Additionally, it is found that throughout the intense geomagnetic storms, Lucknow’s RMSE and MAPE values were higher than Bangalore’s. As a result, when compared to the NeQuick approach, the NN method demonstrated greater accuracy and TEC estimations. The present research concludes that neither the NN nor the NeQuick models can accurately forecast ionospheric TEC for an equatorial station (Bangalore) and an equatorial ionization anomaly (EIA) station in Lucknow throughout intense geomagnetic storms. However, during the recovery period (post-storm), the precision of the forecast increased. © 2023, The Author(s), under exclusive licence to Springer Nature B.V.