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

Performance Analysis of Ionospheric TECmodelsoverthe Africanregion during the geomagnetic storm of March 2015

This paper investigates the diurnal variations of modelled and observed Vertical Total Electron Content (VTEC) over the African region (40oN to+ 40oS, 25oW to 65oE) obtained from

Devanaboyina, Venkata; , others;

Published by:       Published on:

YEAR: 2022     DOI: 10.21203/rs.3.rs-1695991/v1

Assessment of the predictive capabilities of NIGTEC model over Nigeria during geomagnetic storms

The Nigerian Total Electron Content (NIGTEC) is a regional neural network-based model developed by the Nigerian Centre for Atmospheric Research to predict the Total Electron Content (TEC) at any location over Nigeria. The addition of the disturbance storm time (Dst) index as one of NIGTEC s input layer neurons raises a question of its accuracy during geomagnetic storms. In this paper, the capability of NIGTEC in predicting the variability of TEC during geomagnetic storms has been assessed. TEC data predicted by NIGTEC is compared with those derived from Global Navigation Satellite System (GNSS) over Lagos (6.5oN, 3.4oE) and Toro (10.1oN, 9.12oE) during the intense storms in March 2012 and 2013. The model s predictive capability is evaluated in terms of Root Mean Square Error (RMSE). NIGTEC reproduced a fairly good storm time morphology in VTEC driven by the prompt penetration electric field and the increase in thermospheric O/N2. Nevertheless, it failed to predict the increase in TEC after the intense sudden impulse of 60 nT on 8 March 2012. And it could not capture the changes in VTEC driven by the storm time equatorward neutral wind especially during 18:00–24:00 UT. Consequently, the RMSEs were higher during this time window, and the highest RMSE value was obtained during the most intense storm in March 2012.

Amaechi, Paul; Humphrey, Ibifubara; Adewoyin, David;

Published by: Geodesy and Geodynamics      Published on: nov

YEAR: 2021     DOI: 10.1016/j.geog.2021.09.003

geomagnetic storm; global navigation satellite system; Nigerian Total Electron Content (NIGTEC); total electron content

The nighttime ionospheric response and occurrence of equatorial plasma irregularities during geomagnetic storms: a case study

Recent studies revealed that the long-lasting daytime ionospheric enhancements of Total Electron Content (TEC) were sometimes observed in the Asian sector during the recovery phase of geomagnetic storms (e.g., Lei (J Geophys Res Space Phys 123: 3217–3232, 2018), Li (J Geophys Res Space Phys 125: e2020JA028238, 2020). However, they focused only on the dayside ionosphere, and no dedicated studies have been performed to investigate the nighttime ionospheric behavior during such kinds of storm recovery phases. In this study, we focused on two geomagnetic storms that happened on 7–8 September 2017 and 25–26 August 2018, which showed the prominent daytime TEC enhancements in the Asian sector during their recovery phases, to explore the nighttime large-scale ionospheric responses as well as the small-scale Equatorial Plasma Irregularities (EPIs). It is found that during the September 2017 storm recovery phase, the nighttime ionosphere in the American sector is largely depressed, which is similar to the daytime ionospheric response in the same longitude sector; while in the Asian sector, only a small TEC increase is observed at nighttime, which is much weaker than the prominent daytime TEC enhancement in this longitude sector. During the recovery phase of the August 2018 storm, a slight TEC increase is observed on the night side at all longitudes, which is also weaker than the prominent daytime TEC enhancement. For the small-scale EPIs, they are enhanced and extended to higher latitudes during the main phase of both storms. However, during the recovery phases of the first storm, the EPIs are largely enhanced and suppressed in the Asian and American sectors, respectively, while no prominent nighttime EPIs are observed during the second storm recovery phase. The clear north–south asymmetry of equatorial ionization anomaly crests during the second storm should be responsible for the suppression of EPIs during this storm. In addition, our results also suggest that the dusk side ionospheric response could be affected by the daytime ionospheric plasma density/TEC variations during the recovery phase of geomagnetic storms, which further modulates the vertical plasma drift and plasma gradient. As a result, the growth rate of post-sunset EPIs will be enhanced or inhibited.

Wan, Xin; Xiong, Chao; Gao, Shunzu; Huang, Fuqing; Liu, Yiwen; Aa, Ercha; Yin, Fan; Cai, Hongtao;

Published by: Satellite Navigation      Published on: nov

YEAR: 2021     DOI: 10.1186/s43020-021-00055-x

Equatorial plasma irregularity; Geomagneitc storm; Ionospheric response; longitudinal variations; Storm recovery phase

Features of topside ionospheric background over China and its adjacent areas obtained by the ZH-1 satellite

\textlessp\textgreaterTopside ionospheric background distribution and its seasonal variations over China and its adjacent areas, e.g. 0°-54°N and 70°-140°E, are studied using the in situ electron density (Ne) measurements obtained by the LAP payload on board the ZH-1 (CSES) satellite. Results are as followings:(1) Regularities consistent with results from previous studies are shown on the latitudinal extension, longitudinal distribution, and seasonal variations of the EIA (Equatorial Ionization Anomaly) phenomenon in the study area. (2) In the mid-latitude regions, there is a relative low-value zone for the daytime Ne, which shows relative high-value data during nighttime. Nighttime Ne enhancement is shown in all the mid-latitudes for all the seasons when comparing the nighttime and daytime Ne together. The equatorward extension of this phenomenon is in contrast to the poleward extension of the EIA phenomenon; when this phenomenon extends, the EIA shrinks, and vice versa. (3) For the daytime Ne, semiannual anomaly demonstrates a regular pattern, in which the two peaks start in spring and autumn equinoxes at the Equator, then evolve toward the summer solstice with increasing latitude, and finally combine into one summer time peak in mid-latitudes; seasonal anomaly only appears within latitude 4° of the Equator. While for the nighttime Ne, semiannual anomaly appears between latitude 22° and 50°, and seasonal anomaly appears below latitude 22°. (4) The monthly average background of the ionosphere generally shows that the nighttime Ne varies more dramatically than the daytime Ne. For the daytime Ne, observations in both equinoxes and summer solstice vary more violently than that in winter solstice, and observations in EIA regions vary more violently than that in mid-latitude regions. And for the nighttime Ne, observation variations are roughly similar in all seasons and latitudes. (5) Features of the ionospheric background, which fluctuates with time and space in the study area, are relatively complicated, therefore it is necessary to pay attention to the ionosphere background and its fluctuations when conducting studies on ionosphere related scientific problems. Based on the above results and comparisons with other simultaneous observations, we believe that the relative variations of the in situ Ne measurements from the ZH-1 satellite are in consistent with that from other datasets. Besides the well-known ionosphere features, some features which were not found in previous studies are found from the ionosphere background in the study area. The in situ Ne measurements from the ZH-1 satellite are a good data source for systematic studies on ionosphere-related scientific problems due to the similar local times and locations of the observations.\textless/p\textgreater

XiuYing, Wang; DeHe, Yang; ZiHan, Zhou; Jing, C.; Na, Zhou; XuHui, Shen;

Published by: Chinese Journal of Geophysics      Published on: feb

YEAR: 2021     DOI: 10.6038/cjg2021O0152

A Novel Study on the Technique for Far Deriving Ultraviolet O/N Dayglow 2 from Thermospheric Emissions

of TIMED/GUVI to derive the O/N2 [14], and the data of TIMED/GUVI which are recorded by as the data of Polar BEAR/AIRS and TIMED/GUVI. This method uses the intensity ratio of OI

Zhang, Yongchao; Zhu, Jun; Yin, Huan; Zhang, Xiaoxin;

Published by:       Published on:

YEAR: 2017     DOI:

A Novel Study on the Technique for Deriving O/N 2 from Thermospheric Far Ultraviolet Dayglow Emissions

Zhang, Yongchao; Zhu, Jun; Yin, Huan; Zhang, Xiaoxin;

Published by:       Published on:

YEAR: 2017     DOI:

Springer Proceedings in Physics3rd International Symposium of Space Optical Instruments and ApplicationsA Novel Study on the Technique for Deriving O/N2 from Thermospheric Far Ultraviolet Dayglow Emissions

Zhang, Yongchao; Zhu, Jun; Yin, Huan; Zhang, Xiaoxin;

Published by:       Published on:

YEAR: 2017     DOI: 10.1007/978-3-319-49184-410.1007/978-3-319-49184-4_29