Bibliography

Signatures of Equatorial Plasma Bubbles and Ionospheric Scintillations from Magnetometer and GNSS Observations in the Indian Longitudes during the Space Weather Events of Early September 2017

Scintillation due to ionospheric plasma irregularities remains a challenging task for the space science community as it can severely threaten the dynamic systems relying on space-based navigation services. In the present paper, we probe the ionospheric current and plasma irregularity characteristics from a latitudinal arrangement of magnetometers and Global Navigation Satellite System (GNSS) stations from the equator to the far low latitude location over the Indian longitudes, during the severe space weather events of 6–10 September 2017 that are associated with the strongest and consecutive solar flares in the 24th solar cycle. The night-time influence of partial ring current signatures in ASYH and the daytime influence of the disturbances in the ionospheric E region electric currents (Diono) are highlighted during the event. The total electron content (TEC) from the latitudinal GNSS observables indicate a perturbed equatorial ionization anomaly (EIA) condition on 7 September, due to a sequence of M-class solar flares and associated prompt penetration electric fields (PPEFs), whereas the suppressed EIA on 8 September with an inverted equatorial electrojet (EEJ) suggests the driving disturbance dynamo electric current (Ddyn) corresponding to disturbance dynamo electric fields (DDEFs) penetration in the E region and additional contributions from the plausible storm-time compositional changes (O/N2) in the F-region. The concurrent analysis of the Diono and EEJ strengths help in identifying the pre-reversal effect (PRE) condition to seed the development of equatorial plasma bubbles (EPBs) during the local evening sector on the storm day. The severity of ionospheric irregularities at different latitudes is revealed from the occurrence rate of the rate of change of TEC index (ROTI) variations. Further, the investigations of the hourly maximum absolute error (MAE) and root mean square error (RMSE) of ROTI from the reference quiet days’ levels and the timestamps of ROTI peak magnitudes substantiate the severity, latitudinal time lag in the peak of irregularity, and poleward expansion of EPBs and associated scintillations. The key findings from this study strengthen the understanding of evolution and the drifting characteristics of plasma irregularities over the Indian low latitudes.

Vankadara, Ram; Panda, Sampad; Amory-Mazaudier, Christine; Fleury, Rolland; Devanaboyina, Venkata; Pant, Tarun; Jamjareegulgarn, Punyawi; Haq, Mohd; Okoh, Daniel; Seemala, Gopi;

Published by: Remote Sensing      Published on: jan

YEAR: 2022     DOI: 10.3390/rs14030652

space weather; equatorial plasma bubbles; ionospheric irregularity; global navigation satellite system; magnetometer; poleward drift; rate of change of TEC index; scintillations; storm-time electric currents

L-band scintillation and TEC variations on St. Patrick’s Day storm of 17 March 2015 over Indian longitudes using GPS and GLONASS observations

The aim of the present study is to investigate the response of ionospheric total electron content (TEC), Global Positioning System (GPS) and Global Navigation Satellite System (GLONASS) scintillations during 17 March 2015 St. Patrick\textquoterights Day geomagnetic storm over Visakhapatnam, which is popularly known as Waltair (WALT) in the literature. GPS TEC observations obtained from five IGS stations (SGOC, IISC, HYDE, LCK4 and LHAZ) and WALT during the storm have been compared. The TEC derived from GPS, GLONASS constellations and CODE global ionosphere TEC map (GIM) over WALT has also been compared. Positive storm effect during the main phase of the storm and negative storm effect during the recovery phase of the storm were observed over the said stations. The variation of northern equatorial ionisation anomaly TEC (CODE GIM TEC maps) in response to the St. Patrick\textquoterights Day storm over four Indian longitudes (75oE, 80oE, 85oE and 90oE) has also been presented. Strong amplitude and phase scintillations were observed in the L-band signals of GPS and GLONASS constellations over WALT. Twelve satellite (Pseudo Random Noise) PRNs of GPS L1 and nine PRNs of each GLONASS L1 and L2-band signals were affected by strong amplitude and phase scintillation. The peak amplitude scintillation index (S4) obtained from the effected PRNs of GPS L1 signal and GLONASS L1-band signals over WALT range from 0.36 to 0.74 and 0.36 to 0.76, respectively. Strong fluctuations in rate of TEC index are noted over the said stations. This enhanced scintillation activity is mainly due to the main phase of the storm falls in the evening sector over the Indian region.

Srinivasu, K; Prasad, D; Niranjan, K; Seemala, Gopi; Venkatesh, K;

Published by: Journal of Earth System Science      Published on: 03/2019

YEAR: 2019     DOI: 10.1007/s12040-019-1097-6

Conjugate hemisphere ionospheric response to the St. Patrick\textquoterights Day storms of 2013 and 2015 in the 100\textdegreeE longitude sector

The effects of the St. Patrick\textquoterights Day geomagnetic storms of 2013 and 2015 in the equatorial and low-latitude regions of both hemispheres in the 100\textdegreeE longitude sector is investigated and compared with the response in the Indian sector at 77\textdegreeE. The data from a chain of ionosondes and GPS/Global Navigation Satellite Systems receivers at magnetic conjugate locations in the 100\textdegreeE sector have been used. The perturbation in the equatorial zonal electric field due to the prompt penetration of the magnetospheric convective under shielded electric field and the over shielding electric field gives rise to rapid fluctuations in the F₂ layer parameters. The direction of IMF B_z and disturbance electric field perturbations in the sunset/sunrise period is found to play a crucial role in deciding the extent of prereversal enhancement which in turn affect the irregularity formation (equatorial spread F) in the equatorial region. The northward (southward) IMF B_z in the sunset period inhibited (supported) the irregularity formation in 2015 (2013) in the 100\textdegreeE sector. Large height increase (h_mF₂) during sunrise produced short-duration irregularities during both the storms. The westward disturbance electric field on 18 March inhibited the equatorial ionization anomaly causing negative (positive) storm effect in low latitude (equatorial) region. The negative effect was amplified in low midlatitude by disturbed thermospheric composition which produced severe density/total electron content depletion. The longitudinal and hemispheric asymmetry of storm response is observed and attributed to electrodynamic and thermospheric differences.

Kalita, Bitap; Hazarika, Rumajyoti; Kakoti, Geetashree; Bhuyan, P.; Chakrabarty, D.; Seemala, G.; Wang, K.; Sharma, S.; Yokoyama, T.; Supnithi, P.; Komolmis, T.; Yatini, C; Le Huy, M.; Roy, P.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 10/2016

YEAR: 2016     DOI: 10.1002/2016JA023119

Conjugate hemisphere ionospheric response to the St. Patrick s Day storms of 2013 and 2015 in the 100° E longitude sector

The GUVI data used here are provided through support from the NASA MO&DA program. The GUVI instrument was designed and built by The Aerospace Corporation and The John

Kalita, Bitap; Hazarika, Rumajyoti; Kakoti, Geetashree; Bhuyan, PK; Chakrabarty, D; Seemala, Gopi; Wang, K; Sharma, S; Yokoyama, T; Supnithi, P; , others;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2016     DOI: 10.1002/2016JA023119

Conjugate hemisphere ionospheric response to the St. Patrick s Day storms of 2013 and 2015 in the 100° E longitude sector

Kalita, Bitap; Hazarika, Rumajyoti; Kakoti, Geetashree; Bhuyan, PK; Chakrabarty, D; Seemala, Gopi; Wang, K; Sharma, S; Yokoyama, T; Supnithi, P; , others;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2016     DOI:

Ionospheric response to the 17-18 March 2015 geomagnetic storm as seen from multiple TEC and NmF2 measurements along 100° E

Bhuyan, Pradip; Yokoyama, Tatsuhiro; Kalita, Bitap; Seemala, GK; Hazarika, Rumajyoti; Komolmis, Tharadol; Yatini, Clara; Chakrabarty, Dibyendu; Supnithi, Pornchai;

Published by: 41st COSPAR Scientific Assembly      Published on:

YEAR: 2016     DOI:

A comparative study of TEC response for the African equatorial and mid-latitudes during storm conditions

The solar wind effects on the Earth\textquoterights environment are studied for their basic scientific values and crucial practical impacts on technological systems. This paper reports results of Total Electron Content (TEC) changes during two successive ionospheric storms of 7\textendash12 November 2004 using GPS data derived from dual frequency receivers located at African equatorial and midlatitudes. In the geographic coordinate system, equatorial TEC variability is considered over Libreville (0.36\textdegreeN, 9.67\textdegreeE), Gabon and Mbarara (0.60\textdegreeS, 30.74\textdegreeE), Uganda. TEC over midlatitude stations Sutherland (32.38\textdegreeS, 20.81\textdegreeE) and Springbok (29.67\textdegreeS, 17.88\textdegreeE), South Africa are analysed. The analysis of the storm time ionospheric variability over South Africa was undertaken by comparing the critical frequency of the F2 layer (foF2) and the peak height of the F2 layer (hmF2) values obtained from Grahamstown (33.30\textdegreeS, 26.53\textdegreeE) and Madimbo (22.4\textdegreeS, 30.9\textdegreeE) ionosonde measurements. During the analysed storm period it is observed that GPS TEC for midlatitudes was depleted significantly with a corresponding depletion in foF2, due to the reduction in GUVI O/N₂ ratio as observed from its global maps. Over the equatorial latitudes, positive storm effects are more dominant especially during the storm main phase. Negative storm effects are observed over both mid and equatorial latitudes during the recovery phase. A shift in equatorial TEC enhancement (from one GPS station to another) is observed during magnetic storms and has been partially attributed to passage of Travelling Ionospheric Disturbances (TIDs). Magnetometer data over the International Real-time Magnetic Observatory Network (intermagnet) station, Addis Ababa, AAE (9.03\textdegreeN, 38.77\textdegreeE) has been used to help with the explanation of possible causes of equatorial ionospheric TEC dynamics during the analysed magnetic storm period.

Habarulema, John; McKinnell, Lee-Anne; a, Dalia; Zhang, Yongliang; Seemala, Gopi; Ngwira, Chigomezyo; Chum, Jaroslav; Opperman, Ben;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: 09/2013

YEAR: 2013     DOI: 10.1016/j.jastp.2013.05.008

African equatorial and midlatitude TEC dynamics; Magnetic storms; TIDs