GUVI Biblio

Responses of the African-European equatorial-, low-, mid-, and high-latitude ionosphere to geomagnetic storms of 2013, 2015 St Patrick’s Days, 1 June 2013, and 7 October 2015

This study investigates ionospheric responses to 2013 and 2015 St. Patrick’s Days (CME-driven), 1 June 2013 and 7 October 2015 (CIR-driven) geomagnetic storms over the African-

Akala, AO; Afolabi, RO; Otsuka, Y;

Published by: Advances in Space Research      Published on:

YEAR: 2022     DOI: 10.1016/j.asr.2022.10.029

Plasma depletions lasting into daytime during the recovery phase of a geomagnetic storm in May 2017: Analysis and simulation of GPS total electron content observations

This paper reports that plasma density depletions appearing at middle latitudes near sunrise survived until afternoon on 29 May 2017 during the recovery phase of a geomagnetic storm. By analyzing GPS data collected in Japan, we investigate temporal variations in the horizontal two-dimensional distribution of total electron content (TEC) during the geomagnetic storm. The SYM-H index reached −142 nT around 08 UT on 28 May 2017. TEC depletions extending up to approximately 38°N along the meridional direction appeared over Ja ...

Otsuka, Yuichi; Shinbori, Atsuki; Sori, Takuya; Tsugawa, Takuya; Nishioka, Michi; Huba, Joseph;

Published by: Earth and Planetary Physics      Published on:

YEAR: 2021     DOI: 10.26464/epp2021046

Ionosphere; GPS; ionospheric irregularity; plasma bubble; SAMI2

Characteristics of GNSS total electron content enhancements over the mid-latitudes during a geomagnetic storm on November 7 and 8, 2004

The characteristics of global electron density variations in the ionosphere during a geomagnetic storm on November 7 and 8, 2004, were investigated using total electron content (TEC) obtained from the global navigation satellite system (GNSS). The regions of enhanced TEC over North America, Europe, and Japan first appeared in the mid-latitude regions. The TEC enhancements over North America showed a rapid longitudinal expansion and reached a wide longitudinal extent during the initial and main phases of the geomagnetic st ...

Sori, T.; Shinbori, A.; Otsuka, Y.; Tsugawa, T.; Nishioka, M.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 10/2019

YEAR: 2019     DOI: 10.1029/2019JA026713

Characteristics of GNSS total electron content enhancements over the midlatitudes during a geomagnetic storm on 7 and 8 November 2004

Sori, T; Shinbori, A; Otsuka, Y; Tsugawa, T; Nishioka, M;

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

YEAR: 2019     DOI:

Climatology of equatorial plasma bubble observed by MyRTKnet over the years 2008--2013

Malaysia Real-Time Kinematics GNSS Network (MyRTKnet) which consists of 78 GPS receivers was used to investigate the occurrence of equatorial plasma bubble (EPB) along 96\textdegreeE-120\textdegreeE longitude. In this study, we present the monthly occurrence rate of EPB along the geographical longitudes of 96\textdegreeE-120\textdegreeE for a half of solar cycle period (2008-2013). A 2D map of rate of TEC change index (ROTI) projected at 300 km altitude was derived from the signal paths between GPS satellites and the rece ...

Buhari, S.; Abdullah, M.; Yokoyama, T.; Hasbi, A.; Otsuka, Y.; Nishioka, M.; Bahari, S.A.; Tsugawa, T.;

Published by:       Published on: 08/2015

YEAR: 2015     DOI: 10.1109/IconSpace.2015.7283752

Continuous generation and two-dimensional structure of equatorial plasma bubbles observed by high-density GPS receivers in Southeast Asia

High-density GPS receivers located in Southeast Asia (SEA) were utilized to study the two-dimensional structure of ionospheric plasma irregularities in the equatorial region. The longitudinal and latitudinal variations of tens of kilometer-scale irregularities associated with equatorial plasma bubbles (EPBs) were investigated using two-dimensional maps of the rate of total electron content change index (ROTI) from 127 GPS receivers with an average spacing of about 50\textendash100 km. The longitudinal variations of the tw ...

Buhari, S.; Abdullah, M.; Hasbi, A.; Otsuka, Y.; Yokoyama, T.; Nishioka, M.; Tsugawa, T.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 12/2014

YEAR: 2014     DOI: 10.1002/jgra.v119.1210.1002/2014JA020433

equatorial plasma bubble; GPS-ROTI map; GPS-TEC

Physical mechanisms of the ionospheric storms at equatorial and higher latitudes during the recovery phase of geomagnetic storms

The paper studies the physical mechanisms of the ionospheric storms at equatorial and higher latitudes, which are generally opposite both during the main phase (MP) and recovery phase (RP) of geomagnetic storms. The mechanisms are based on the natural tendency of physical systems to occupy minimum energy state which is most stable. The paper first illustrates the recent developments in the understanding of the mechanisms during daytime MPs when generally negative ionospheric storms (in Nmax and TEC) develop at equatorial ...

Balan, N.; Otsuka, Y.; Nishioka, M.; Liu, J; Bailey, G.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2013

YEAR: 2013     DOI: 10.1002/jgra.50275

Geomagnetic storms; Ionospheric storms; physical mechanisms

Ionospheric and thermospheric storms at equatorial latitudes observed by CHAMP, ROCSAT, and DMSP

Balan, N.; Liu, J; Otsuka, Y.; Ram, Tulasi; ühr, H.;

Published by: Journal of Geophysical Research      Published on: Jan-01-2012

YEAR: 2012     DOI: 10.1029/2011JA016903

Response of low-latitude ionosphere to medium-term changes of solar and geomagnetic activity

Kutiev, Ivan; Otsuka, Yuichi; Pancheva, Dora; Heelis, Rod;

Published by: Journal of Geophysical Research      Published on: Jan-01-2012

YEAR: 2012     DOI: 10.1029/2012JA017641

Relative effects of electric field and neutral wind on positive ionospheric storms

The paper studies the relative importance of penetrating eastward electric field (PEEF) and direct effects of equatorward neutral wind in leading to positive ionospheric storms at low-mid

Balan, N; Alleyne, H; Otsuka, Y; Lekshmi, Vijaya; Fejer, BG; McCrea, I;

Published by: Earth, planets and space      Published on:

YEAR: 2009     DOI:

Simultaneous appearance of isolated auroral arcs and Pc 1 geomagnetic pulsations at subauroral latitudes

Sakaguchi, Kaori; Shiokawa, Kazuo; Miyoshi, Yoshizumi; Otsuka, Yuichi; Ogawa, Tadahiko; Asamura, Kazushi; Connors, M;

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

YEAR: 2008     DOI:

F3 layer during penetration electric field

The occurrence of an additional layer, called F3 layer, in the equatorial ionosphere at American, Indian, and Australian longitudes during the super double geomagnetic storm of 7–11 November 2004 is presented using observations and modeling. The observations show the occurrence, reoccurrence, and quick ascent to the topside ionosphere of unusually strong F3 layer in Australian longitude during the first super storm (8 November) and in Indian longitude during the second super storm (10 November), all with large reductions i ...

Balan, N.; Thampi, S.; Lynn, K.; Otsuka, Y.; Alleyne, H.; Watanabe, S.; Abdu, M.; Fejer, B.;

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

YEAR: 2008     DOI: https://doi.org/10.1029/2008JA013206

F3 layer; penetration; Electric field

Summer-winter hemispheric asymmetry of the sudden increase in ionospheric total electron content and of the O/N ₂ ratio: Solar activity dependence

Tsugawa, T.; Zhang, S.-R.; Coster, A.; Otsuka, Y.; Sato, J.; Saito, A.; Zhang, Y.; Paxton, L.;

Published by: Journal of Geophysical Research      Published on: Jan-01-2007

YEAR: 2007     DOI: 10.1029/2007JA012415

Low-latitude total electron content enhancement at low geomagnetic activity observed over Japan

Kutiev, Ivan; Otsuka, Yuichi; Saito, Akinori; Tsugawa, Takuya;

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

YEAR: 2007     DOI:

Summer-winter hemispheric asymmetry of the sudden increase in ionospheric total electron content and of the O/N2 ratio: Solar activity dependence

Tsugawa, T; Zhang, S-R; Coster, AJ; Otsuka, Y; Sato, J; Saito, A; Zhang, Y; Paxton, LJ;

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

YEAR: 2007     DOI:

The ionospheric response in the Brazilian sector during the super geomagnetic storm on 20 November 2003

Becker-Guedes, F; Sahai, Y; Fagundes, PR; Espinoza, ES; Pillat, VG; Lima, WLC; Basu, Su; Basu, Sa; Otsuka, Y; Shiokawa, K; MacKenzie, E.; Bittencourt, J.;

Published by:       Published on:

YEAR: 2007     DOI:

Summer-Winter Hemispheric Asymmetry of Sudden Increase in Ionospheric Total Electron Content

Tsugawa, T; Zhang, S; Coster, A; Otsuka, Y; Sato, J; Saito, A; Zhang, Y; Paxton, L;

Published by:       Published on:

YEAR: 2006     DOI:

Simultaneous ground-and satellite-based airglow observations of geomagnetic conjugate plasma bubbles in the equatorial anomaly

We compare, for the first time, geomagnetically-conjugate plasma bubbles observed by ground-based OI 630.0-nm all-sky imagers at Shigaraki, Japan (34.8◦ N, 136.1◦ E; magnetic

Ogawa, Tadahiko; Sagawa, Eiichi; Otsuka, Yuichi; Shiokawa, Kazuo; Immel, Thomas;

Published by: Earth, planets and space      Published on:

YEAR: 2005     DOI: 10.1186/BF03351822

Time evolution of high-altitude plasma bubbles imaged at geomagnetic conjugate points

Temporal and spatial evolution of two high-altitude plasma bubbles (evening and midnight) was observed on 4 April 2002, at geomagnetic conjugate points at Sata, Japan (magnetic

Shiokawa, K; Otsuka, Y; Ogawa, T; Wilkinson, P;

Published by:       Published on:

YEAR: 2004     DOI: