SHARAD CHANDRA TRIPATHI

@vitbhopal.ac.in

Assistant Professor, School of Advanced Sciences and Languages
VIT Bhopal University

SHARAD CHANDRA TRIPATHI


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https://researchid.co/sharadctripathi

RESEARCH INTERESTS

Space Weather, Solar Physics, Ionospheric Physics, Earth System Science
13

Scopus Publications

87

Scholar Citations

5

Scholar h-index

2

Scholar i10-index

Scopus Publications

  • Ionospheric Variability During the 10 October 2024 Geomagnetic Storm: A Regional Analysis Across Europe
    Sharad C. Tripathi, Haris Haralambous, Trisani Biswas
    Atmosphere, 2025
    This study examines the ionospheric response to the intense geomagnetic storm of 9–12 October 2024 over the European sector. Digisonde data from mid-latitude European stations and in situ electron density measurements from Swarm A and B satellites were used to analyze variations in key ionospheric characteristics, including the critical frequency (foF2), peak height (hmF2) and plasma drift velocities. Significant uplift of the F2 layer and a corresponding reduction in foF2 were observed across latitudes, primarily driven by prompt penetration electric fields (PPEFs) and storm-induced thermospheric winds. Horizontal and vertical ion drifts showed large asymmetries and reversals, with zonal drift velocities exceeding 1000 m/s at some stations. Swarm observations confirmed plasma density enhancements during the main phase and notable depletions during recovery, particularly after 1:00 UT on 11 October. The midlatitude ionospheric trough (MIT) intensified during the recovery phase, as can be seen from Swarm B. These variations were shaped by electrodynamic forcing, compositional changes and disturbance dynamo electric fields (DDEFs). The results emphasize the role of solar wind drivers, latitude-dependent electrodynamic coupling and thermospheric dynamics in mid-latitude ionospheric variability during geomagnetic storms.
  • Effects of the October 2024 Storm over the Global Ionosphere
    Krishnendu Sekhar Paul, Haris Haralambous, Mefe Moses, Sharad C. Tripathi
    Remote Sensing, 2025
    The present study analyzes the global ionospheric response to the intense geomagnetic storm of 10–11 October 2024 (SYM—H minimum of −346 nT), using observations from COSMIC—2 and Swarm satellites, GNSS TEC, and Digisondes. Significant uplift of the F-region was observed across both Hemispheres on the dayside, primarily driven by equatorward thermospheric winds and prompt penetration electric fields (PPEFs). However, this uplift did not correspond with increases in foF2 due to enhanced molecular nitrogen-promoting recombination in sunlit regions and the F2 peak rising beyond the COSMIC—2 detection range. In contrast, in the Southern Hemisphere nightside ionosphere exhibited pronounced Ne depletion and low hmF2 values, attributed to G-conditions and thermospheric composition changes caused by storm-time circulation. Strong vertical plasma drifts exceeding 100 m/s were observed during both the main and recovery phases, particularly over Ascension Island, driven initially by southward IMF—Bz-induced PPEFs and later by disturbance dynamo electric fields (DDEFs) as IMF—Bz turned northward. Swarm data revealed a poleward expansion of the Equatorial Ionization Anomaly (EIA), with more pronounced effects in the Southern Hemisphere due to seasonal and longitudinal variations in ionospheric conductivity. Additionally, the storm excited Large-Scale Travelling Ionospheric Disturbances (LSTIDs), triggered by thermospheric perturbations and electrodynamic drivers, including PPEFs and DDEFs. These disturbances, along with enhanced westward thermospheric wind and altered zonal electric fields, modulated ionospheric irregularity intensity and distribution. The emergence of anti-Sq current systems further disrupted quiet-time electrodynamics, promoting global LSTID activity. Furthermore, storm-induced equatorial plasma bubbles (EPBs) were observed over Southeast Asia, initiated by enhanced PPEFs during the main phase and suppressed during recovery, consistent with super EPB development mechanisms.
  • Spectroscopic diagnosis of a B-class flare and an associated filament eruption
    B. Suresh Babu, Pradeep Kayshap, Sharad C. Tripathi
    Astrophysics and Space Science, 2025
  • Self-absorption in solar surge as observed by IRIS
    B. Suresh Babu, Pradeep Kayshap, Sharad C. Tripathi
    Astrophysics and Space Science, 2024
  • Spectroscopic diagnostic of the footpoints of the cool loops
    B Suresh Babu, Pradeep Kayshap, Sharad C Tripathi, P Jelínek, B N Dwivedi
    Monthly Notices of the Royal Astronomical Society, 2024
    Statistically, the cool loop’s footpoints are diagnosed using Si iv resonance lines observations provided by Interface Region Imaging Spectrograph (IRIS). The intensity and full width at half-maximum (FWHM) of the loop’s footpoints in β–γ active regions (ARs) are higher than the corresponding parameters of footpoints in β ARs. However, the Doppler velocity of footpoints in both ARs are almost similar to each other. The intensities of footpoints from β–γ AR is found to be around nine times that of β AR when both ARs are observed nearly at the same time. The same intensity difference reduces nearly to half (four times) when considering all ARs observed over 9 yr. Hence, the instrument degradation affects comparative intensity analysis. We find that Doppler velocity and FWHM are well correlated while peak intensity is neither correlated with Doppler velocity nor FWHM. The loop’s footpoints in β–γ ARs have around four times more complex Si iv spectral profiles than that of β ARs. The intensity ratios (Si iv 1393.78 Å/1402.77 Å) of the significant locations of footpoints differ, marginally, (i.e. either less than 1.9 or greater than 2.10) from the theoretical ratio of 2, i.e. 52 per cent (55 per cent) locations in β (β–γ) ARs significantly deviate from 2. Hence, we say that more than half of the footpoint locations are either affected by the opacity or resonance scattering. We conclude that the nature and attributes of the footpoints of the cool loops in β–γ ARs are significantly different from those in β ARs.
  • Study of Ionospheric behaviour during the intense geomagnetic storms in 24th solar cycle over different Latitudes and Longitudes
    Bhupendra Malvi, Sharad C. Tripathi, P. K. Purohit
    Proceedings of the International Astronomical Union, 2023
    An analysis of geomagnetic disturbances and global ionospheric electron density perturbations during the 2015 St. Patrick’s Day geomagnetic storm is presented in this paper. GPS observations from worldwide IGS stations are used and analysed through GPS-TEC analysis application developed by Gopi Seemala to get VTEC profiles. The St. Patrick’s geomagnetic storm covers the interval of 15-23 March 2015, when transient solar eruptions (a prolonged C9-class solar flare and associated CMEs on 15 March) and a strong geomagnetic storm during 16-18 March (Dst dropped to -223 nT) were reported. This geomagnetic storm led to complex effects on the ionosphere. The global maps have been created after analysing VTEC profiles at Low, Mid and High-latitudes over different longitudinal sectors. Major features of the positive and negative ionospheric storm development are observed in Asian, European and American Low, Mid and High-latitudes.
  • Diagnostics of homologous solar-surge plasma as observed by IRIS and SDO
    Pradeep Kayshap, Rajdeep Singh Payal, Sharad C Tripathi, Harihara Padhy
    Monthly Notices of the Royal Astronomical Society, 2021
    Surges have regularly been observed in mostly H α 6563 Å and Ca ii 8542 Å. However, surge responses to other prominent lines of the interface region (Mg ii k 2796.35 Å and h 2803.52 Å, O iv 1401.15 Å, Si iv 1402.77 Å) are not well studied. Here, the evolution and kinematics of six homologous surges are analysed using IRIS and AIA observations. These surges were observed on 2014 July 7 and were located very close to the limb. A differential emission measure analysis is performed on these surges where the coexistence of cool (log T/K = 6.35) and relatively hot (log T/K = 6.95) components has been found at the base. This demonstrates that the bases of surges undergo substantial heating. During the emission of these surges in the above-mentioned interface-region lines, reported here for the first time, two peaks have been observed in the initial phase of emission, where one peak is found to be constant while other one varies; i.e. is non-constant (observed red- to blueshifts across the surge evolution) in nature. This suggests the rotational motion of surge plasma. The heated base and rotating plasma suggest the occurrence of magnetic reconnection as the most likely trigger for homologous surges. During the emission of these surges, it is found that, despite them being optically thick (i.e. Rkh < 2.0), central reversal was not observed for the Mg ii k and h lines. Further, Rkh increases with surge emission in time and it is found to have a positive correlation with Doppler velocity and negative with Gaussian width.
  • Evaluation of geomagnetic storm effects on the GPS derived Total Electron Content (TEC)
    P K Purohit, Azad A Mansoori, Parvaiz A Khan, Roshni Atulkar, Purushottam Bhawre, Sharad C Tripathi, Prakash Khatarkar, Shivangi Bhardwaj, A M Aslam, Malik A Waheed, A K Gwal
    Journal of Physics Conference Series, 2015
    The geomagnetic storm represents the most outstanding example of solar wind- magnetospheric interaction, which causes global disturbances in the geomagnetic field as well as triggers ionospheric disturbances. We study the behaviour of ionospheric Total Electron Content (TEC) during the geomagnetic storms. For this investigation we have selected 47 intense geomagnetic storms (Dst ≤ -100nT) that were observed during the solar cycle 23 i.e. during 1998- 2006. We then categorized these storms into four categories depending upon their solar sources like Magnetic Cloud (MC), Co-rotating Interaction Region (CIR), SH+ICME and SH+MC. We then studied the behaviour of ionospheric TEC at a mid latitude station Usuda (36.13N, 138.36E), Japan during these storm events produced by four different solar sources. During our study we found that the smooth variations in TEC are replaced by rapid fluctuations and the value of TEC is strongly enhanced during the time of these storms belonging to all the four categories. However, the greatest enhancements in TEC are produced during those geomagnetic storms which are either caused by Sheath driven Magnetic cloud (SH+MC) or Sheath driven ICME (SH+ICME). We also derived the correlation between the TEC enhancements produced during storms of each category with the minimum Dst. We found the strongest correlation exists for the SH+ICME category followed by SH+MC, MC and finally CIR. Since the most intense storms were either caused by SH+ICME or SH+MC while the least intense storms were caused by CIR, consequently the correlation was strongest with SH+ICME and SH+MC and least with CIR.
  • Investigation of effects of geomagnetic storms produced by different solar sources on the Total Electron Content (TEC)
    P. K. Purohit, Azad A. Mansoori, Parvaiz A. Khan, Purushottam Bhawre, Sharad C. Tripathi, A. M. Aslam, Malik A. Waheed, A. K. Gwal
    Icops Beams 2014 41st IEEE International Conference on Plasma Science and the 20th International Conference on High Power Particle Beams, 2015
    The geomagnetic storm represents the most outstanding example of solar wind- magnetospheric interaction, which causes global disturbances in the geomagnetic field as well as the trigger ionospheric disturbances. Under this problem we study the behaviour of ionospheric Total Electron Content (TEC) during the geomagnetic storms. For the present investigation we have selected 47 intense geomagnetic storms (Dst ≤ -100nT) that during the solar cycle 23 i.e. during 1998- 2006. We then categorized these storms into four categories depending upon their solar sources like Magnetic Cloud (MC), Co-rotating Interaction Region (CIR), SH+ICME and SH+MC. We then studied the behaviour of ionospheric TEC at a mid latitude station Usuda (), Japan during these storm events. During our study we found that the smooth variations in TEC are replaced by rapid fluctuations and the value of TEC is strongly enhanced during the time of these storms belonging to all the four categories. However, the greatest enhancements in TEC are produced during those geomagnetic storms which are either caused by Sheath driven Magnetic cloud (SH+MC) or Sheath driven ICME (SH+ICME). We also derived the correlation between the TEC enhancements produced during storms of each category with the minimum Dst. We found the the strongest correlation exists for the SH+ICME category followed by SH+MC, MC and finally CIR. Since the most intense storms were either caused by SH+ICME or SH+MC while the least intense storms were caused by CIR, consequently the correlation was strongest with SH+ICME and SH+MC and least with CIR.
  • Solar transients disturbing the terrestrial magnetic environment at higher latitudes
    Parvaiz A. Khan, Sharad C. Tripathi, O. A. Troshichev, Malik A. Waheed, A. M. Aslam, A. K. Gwal
    Astrophysics and Space Science, 2014
    Geomagnetic field variations during five major Solar Energetic Particle (SEP) events of solar cycle 23 have been investigated in the present study. The SEP events of 1 October 2001, 4 November 2001, 22 November 2001, 21 April 2002 and 14 May 2005 have been selected to study the geomagnetic field variations at two high-latitude stations, Thule (77.5∘ N, 69.2∘ W) and Resolute Bay (74.4∘ E, 94.5∘ W) of the northern polar cap. We have used the GOES proton flux in seven different energy channels (0.8–4 MeV, 4–9 MeV, 9–15 MeV, 15–40 MeV, 40–80 MeV, 80–165 MeV, 165–500 MeV). All the proton events were associated with geoeffective or Earth directed CMEs that caused intense geomagnetic storms in response to geospace. We have taken high-latitude indices, AE and PC, under consideration and found fairly good correlation of these with the ground magnetic field records during the five proton events. The departures of the H component during the events were calculated from the quietest day of the month for each event and have been represented as ΔHTHL and ΔHRES for Thule and Resolute Bay, respectively. The correspondence of spectral index, inferred from event integrated spectra, with ground magnetic signatures ΔHTHL and ΔHRES along with Dst and PC indices have been brought out. From the correlation analysis we found a very strong correlation to exist between the geomagnetic field variation (ΔHs) and high-latitude indices AE and PC. To find the association of geomagnetic storm intensity with proton flux characteristics we derived the correspondence between the spectral indices and geomagnetic field variations (ΔHs) along with the Dst and AE index. We found a strong correlation (0.88) to exist between the spectral indices and ΔHs and also between spectral indices and AE and PC.
  • Investigation on spectral behavior of Solar transients and their interrelationship
    Sharad C. Tripathi, Parvaiz A. Khan, A. M. Aslam, A. K. Gwal, P. K. Purohit, Rajmal Jain
    Astrophysics and Space Science, 2013
  • Influence of solar flare X-rays on the habitability on the Mars
    Rajmal Jain, Arun K. Awasthi, Sharad C. Tripathi, Nipa J. Bhatt, Parvaiz A. Khan
    Icarus, 2012
  • Effect of enhanced X-ray flux on the D and F layer ionospheric ionization during extreme solar events
    Sharad C. Tripathi, Parwaiz A. Khan, Azad Ahmad, Purushottam Bhavre, P.K. Purohit, A.K. Gwal
    2011 IEEE International Conference on Space Science and Communication Towards Exploring the Equatorial Phenomena Iconspace 2011 Proceedings, 2011

RECENT SCHOLAR PUBLICATIONS

  • Ionospheric Variability During the 10 October 2024 Geomagnetic Storm: A Regional Analysis Across Europe
    SC Tripathi, H Haralambous, T Biswas
    Atmosphere 16 (9), 1029 , 2025
    2025
    Citations: 5
  • Effects of the October 2024 storm over the global ionosphere
    KS Paul, H Haralambous, M Moses, SC Tripathi
    Remote Sensing 17 (13), 2329 , 2025
    2025
    Citations: 16
  • Spectroscopic diagnosis of a B-class flare and an associated filament eruption
    BS Babu, P Kayshap, SC Tripathi
    Astrophysics and Space Science 370 (2), 13 , 2025
    2025
    Citations: 2
  • Self-absorption in solar surge as observed by IRIS
    BS Babu, P Kayshap, SC Tripathi
    Astrophysics and Space Science 369 (6), 61 , 2024
    2024
    Citations: 2
  • Spectroscopic diagnostic of the footpoints of the cool loops
    BS Babu, P Kayshap, SC Tripathi, P Jelínek, BN Dwivedi
    Monthly Notices of the Royal Astronomical Society 528 (2), 2474-2489 , 2024
    2024
    Citations: 5
  • Study of Ionospheric behaviour during the intense geomagnetic storms in 24th solar cycle over different Latitudes and Longitudes
    B Malvi, SC Tripathi, PK Purohit
    Proceedings of the International Astronomical Union 18 (S372), 76-80 , 2022
    2022
  • Diagnostics of homologous solar-surge plasma as observed by IRIS and SDO
    P Kayshap, R Singh Payal, SC Tripathi, H Padhy
    Monthly Notices of the Royal Astronomical Society 505 (4), 5311-5326 , 2021
    2021
    Citations: 14
  • GEOMAGNETIC STORMS AND THEIR RESPONSE IN IONOSPHERE
    MA Waheed, SC Tripathi, PA Khan, AK Gwal
    Contemporary Research in Sciences and Humanities, 54 , 2017
    2017
  • Geomagnetic response to IMF and solar wind over different latitudes
    AM Aslam, SC Tripathi, AA Mansoori, MA Waheed
    41st COSPAR Scientific Assembly 41, D3. 3-21-16 , 2016
    2016
  • A long-term study of the impact of solar flares on ionospheric characteristics measured by digisondes and GNSS receivers
    SC Tripathi, H Haralambous, T Das
    41st COSPAR Scientific Assembly 41, D2. 1-55-16 , 2016
    2016
  • Evaluation of geomagnetic storm effects on the GPS derived Total Electron Content (TEC)
    PK Purohit, AA Mansoori, PA Khan, R Atulkar, P Bhawre, SC Tripathi, ...
    Journal of Physics: Conference Series 640 (1), 012072 , 2015
    2015
    Citations: 8
  • Space Weather: The Sun-Earth Perspectives
    SC Tripathi
    Scholars' Press , 2015
    2015
  • Long term evolution of geomagnetic activity under the influence of 11 year cyclic variations in solar activity during solar cycle 23 and 24
    Malik A. Waheed, Parvaiz A. Khan, Sharad C. Tripathi, A. M. Aslam, Azad A ...
    2015
    Citations: 5
  • Investigation of effects of geomagnetic storms produced by different solar sources on the Total Electron Content (TEC)
    PK Purohit, AA Mansoori, PA Khan, P Bhawre, SC Tripathi, AM Aslam, ...
    2014 IEEE 41st International Conference on Plasma Sciences (ICOPS) held with … , 2014
    2014
  • Observations for the Role of Flux rope Eruption in a Geoeffective Solar Flare
    AM Aslam, PA Khan, SC Tripathi, AA Mansoori, P Bhawre, AK Gwal
    Journal: Journal of Advances in Physics 4 (2), 555-564 , 2014
    2014
  • Parvaiz A. Khan, Sharad C. Tripathi, OA Troshichev, Malik A. Waheed
    AM Aslam, AK Gwal
    Astrophys Space Sci 349, 647-656 , 2014
    2014
  • Spectral characteristics of Solar Transients and their response to Geospace in terms of Magnetic Field perturbations and Current Systems
    SC Tripathi, AK Gwal, R Jain, AA Mansoori, M Aslam A, PA Khan, ...
    40th COSPAR Scientific Assembly 40, D2. 5-86-14 , 2014
    2014
  • A study on delay between peak Dst and IMF, solar wind parameters
    M Aslam A, AK Gwal, SC Tripathi, AA Mansoori, PA Khan, MA Waheed, ...
    40th COSPAR Scientific Assembly 40, D3. 3-42-14 , 2014
    2014
  • Evaluation of long term solar activity effects on GPS performances
    AA Mansoori, AK Gwal, SC Tripathi, M Aslam A, PA Khan, PK Purohit, ...
    40th COSPAR Scientific Assembly 40, C1. 1-77-14 , 2014
    2014
  • Delayed response of Solar Energetic Particles at Geospace
    PA Khan, SC Tripathi, AA Mansoori, M Aslam A, PK Purohit, MA Waheed, ...
    40th COSPAR Scientific Assembly 40, D2. 5-120-14 , 2014
    2014

MOST CITED SCHOLAR PUBLICATIONS

  • Effects of the October 2024 storm over the global ionosphere
    KS Paul, H Haralambous, M Moses, SC Tripathi
    Remote Sensing 17 (13), 2329 , 2025
    2025
    Citations: 16
  • Diagnostics of homologous solar-surge plasma as observed by IRIS and SDO
    P Kayshap, R Singh Payal, SC Tripathi, H Padhy
    Monthly Notices of the Royal Astronomical Society 505 (4), 5311-5326 , 2021
    2021
    Citations: 14
  • Evaluation of geomagnetic storm effects on the GPS derived Total Electron Content (TEC)
    PK Purohit, AA Mansoori, PA Khan, R Atulkar, P Bhawre, SC Tripathi, ...
    Journal of Physics: Conference Series 640 (1), 012072 , 2015
    2015
    Citations: 8
  • Scientific efforts in the direction of successful Earthquake Prediction
    PA Khan, SC Tripathi, AA Mansoori, P Bhawre, PK Purohit, AK Gwal
    International Journal of Geomatics and Geosciences 1 (4), 669 , 2011
    2011
    Citations: 8
  • Influence of solar flare X-rays on the habitability on the Mars
    R Jain, AK Awasthi, SC Tripathi, NJ Bhatt, PA Khan
    Icarus 220 (2), 889-895 , 2012
    2012
    Citations: 7
  • Ionospheric Variability During the 10 October 2024 Geomagnetic Storm: A Regional Analysis Across Europe
    SC Tripathi, H Haralambous, T Biswas
    Atmosphere 16 (9), 1029 , 2025
    2025
    Citations: 5
  • Spectroscopic diagnostic of the footpoints of the cool loops
    BS Babu, P Kayshap, SC Tripathi, P Jelínek, BN Dwivedi
    Monthly Notices of the Royal Astronomical Society 528 (2), 2474-2489 , 2024
    2024
    Citations: 5
  • Long term evolution of geomagnetic activity under the influence of 11 year cyclic variations in solar activity during solar cycle 23 and 24
    Malik A. Waheed, Parvaiz A. Khan, Sharad C. Tripathi, A. M. Aslam, Azad A ...
    2015
    Citations: 5
  • Investigation on spectral behavior of Solar transients and their interrelationship
    SC Tripathi, PA Khan, AM Aslam, AK Gwal, PK Purohit, R Jain
    Astrophysics and Space Science , 2013
    2013
    Citations: 5
  • Effect of enhanced X-ray flux on the D and F layer ionospheric ionization during extreme solar events
    SC Tripathi, PA Khan, A Ahmad, P Bhawre, PK Purohit, AK Gwal
    Proceeding of the 2011 IEEE International Conference on Space Science and … , 2011
    2011
    Citations: 5
  • Solar Transients disturbing the Terrestrial Magnetic Environment at Higher Latitudes
    PA Khan, SC Tripathi, OA Troshichev, MA Waheed, AM Aslam, AK Gwal
    arXiv preprint arXiv:1310.4916 , 2013
    2013
    Citations: 4
  • Spectroscopic diagnosis of a B-class flare and an associated filament eruption
    BS Babu, P Kayshap, SC Tripathi
    Astrophysics and Space Science 370 (2), 13 , 2025
    2025
    Citations: 2
  • Self-absorption in solar surge as observed by IRIS
    BS Babu, P Kayshap, SC Tripathi
    Astrophysics and Space Science 369 (6), 61 , 2024
    2024
    Citations: 2
  • Response of High Latitude Ionospheric TEC to Enhanced Radiation Fluxes during the Major Solar Flare Events
    S TRIPATHI
    Journal of Scientific Research , 2013
    2013
    Citations: 1
  • Study of Ionospheric behaviour during the intense geomagnetic storms in 24th solar cycle over different Latitudes and Longitudes
    B Malvi, SC Tripathi, PK Purohit
    Proceedings of the International Astronomical Union 18 (S372), 76-80 , 2022
    2022
  • GEOMAGNETIC STORMS AND THEIR RESPONSE IN IONOSPHERE
    MA Waheed, SC Tripathi, PA Khan, AK Gwal
    Contemporary Research in Sciences and Humanities, 54 , 2017
    2017
  • Geomagnetic response to IMF and solar wind over different latitudes
    AM Aslam, SC Tripathi, AA Mansoori, MA Waheed
    41st COSPAR Scientific Assembly 41, D3. 3-21-16 , 2016
    2016
  • A long-term study of the impact of solar flares on ionospheric characteristics measured by digisondes and GNSS receivers
    SC Tripathi, H Haralambous, T Das
    41st COSPAR Scientific Assembly 41, D2. 1-55-16 , 2016
    2016
  • Space Weather: The Sun-Earth Perspectives
    SC Tripathi
    Scholars' Press , 2015
    2015
  • Investigation of effects of geomagnetic storms produced by different solar sources on the Total Electron Content (TEC)
    PK Purohit, AA Mansoori, PA Khan, P Bhawre, SC Tripathi, AM Aslam, ...
    2014 IEEE 41st International Conference on Plasma Sciences (ICOPS) held with … , 2014
    2014