Results 31 to 40 of about 588 (83)

Evolution of Post‐Sunset EPBs: Relationships to the EIA Induced by Pre‐Reversal Enhancement Electric Fields

Space Weather, Volume 23, Issue 7, July 2025.
Abstract This paper presents Global Navigation Satellite System radio occultation (RO) observational analyses on deducing the relationships and dependences between post‐sunset equatorial plasma bubbles (EPB) occurrences and equatorial ionospheric anomaly (EIA) strength variability.
Lung‐Chih Tsai, Shin‐Yi Su, Harald Schuh, Mohamad Mahdi Alizadeh, Jens Wickert   +4 more
wiley   +1 more source

Indian Equatorial Ionosphere Under the Influence of the May 2024 Geomagnetic Storm: Insights Into Electric Fields, Plasma Irregularities and F‐Region Dynamics

Earth and Space Science, Volume 12, Issue 5, May 2025.
Abstract This study investigates the distinctive features of the daytime equatorial E‐region ionosphere using observations of HF radar (18 MHz), ionosonde, and magnetometer at Thumba (8.5°N, 77°E, dip lat = 1.9°N), India, during the extreme geomagnetic storm of May 10–11, 2024 (minimum SYM‐H ∼ −497 nT).
Lalitha G. Krishnan, Tarun Kumar Pant, T. Manu, C. Vineeth, Lijo Jose, Reuben Samson Yaqub, K. S. Vishnupriya, T. V. Sruthi   +7 more
wiley   +1 more source

Global diagnostics of ionospheric absorption during X-ray solar flares based on 8-20MHz noise measured by over-the-horizon radars [PDF]

, 2018
An analysis of noise attenuation during eighty solar flares between 2013 and 2017 was carried out at frequencies 8-20 MHz using thirty-four SuperDARN radars and the EKB ISTP SB RAS radar.
Berngardt, O. I., Ruohoniemi, J. M., St-Maurice, J. -P., Marchaudon, A., Kosch, M. J., Yukimatu, A. S., Nishitani, N., Shepherd, S. G., Marcucci, M. F., Hu, H., Nagatsuma, T., Lester, M.   +11 more
core   +4 more sources

The Propagation and Evolution of Polar Cap Patches During Auroral Substorm Activity

Journal of Geophysical Research: Space Physics, Volume 130, Issue 5, May 2025.
Abstract Polar cap patches are islands of enhanced plasma density formed during intervals of southward interplanetary magnetic field (IMF). The present study examines the observations of polar cap patches during sequential auroral substorms that occurred on 9 September 2011.
Jianjun Liu, Yaqi Jin, Xiangcai Chen, Zhiwei Wang, Fang He, Zejun Hu, Akira Sessai Yukimatu, William Bristow, Hongqiao Hu, Beichen Zhang   +9 more
wiley   +1 more source

Generalized Force Method for Point‐To‐Point Ray Tracing in Anisotropic Ionosphere: Implementation and Applications to NeQuick2 and IGRF13 Models

Radio Science, Volume 60, Issue 3, March 2025.
Abstract The generalized force method, previously developed for an isotropic inhomogeneous ionosphere, exploits the knowledge about the character of the extrema of the phase distance—where high ionospheric rays correspond to minima and low rays to saddle points—to systematically find all relevant rays between fixed points, thereby enabling efficient ...
I. A. Nosikov, M. V. Klimenko, A. M. Padokhin, V. V. Nosikova, P. F. Bessarab   +4 more
wiley   +1 more source

Application of SuperDARN Interferometry for Improved Estimates of Doppler Velocity and Echo Geolocation

Radio Science, Volume 60, Issue 1, January 2025.
Abstract It has been previously established that the Doppler velocities of F‐region ionospheric echoes observed by the Super Dual Auroral Radar Network (SuperDARN) at high frequencies (HF, 8–20 MHz) are persistently lower than those measured by other instruments at the same locations. This was attributed to the ionospheric refractive index for HF radio
P. Ponomarenko, M. Ghalamkarian Nejad, A. V. Koustov   +2 more
wiley   +1 more source

Experimental studies of ionospheric irregularities and related plasma processes [PDF]

Utah State University (USU) continued its program of measuring and interpreting electron density and its variations in a variety of ionospheric conditions with the Experimental Studies of Ionospheric Irregularities and Related Plasma Processes program ...
Baker, Kay D.
core   +1 more source

On the Growth and Evolution of Nocturnal Ionospheric Irregularities Using HF Radar Observations Along With Digisonde and GNSS Data Over Trivandrum, India

Space Weather, Volume 22, Issue 11, November 2024.
Abstract The growth and evolution of nocturnal ionospheric plasma irregularities are analyzed over the geomagnetic equatorial station Trivandrum (8.5°N, 77°E, dip latitude 1.9°N) using multi‐instrumental techniques during various seasons of moderate and high solar activity periods.
T. V. Sruthi, G. Manju
wiley   +1 more source

Monitoring of Ionospheric Variability Using the Low lAtitude Long Range Ionospheric raDar (LARID): Capabilities, Advantages and Limitations

Space Weather, Volume 22, Issue 11, November 2024.
Abstract A Low lAtitude long Range Ionospheric raDar (LARID), which was built recently at Dongfang (19.2°N, 108.8°E, magnetic latitude 13.9°), Hainan Is., China, is employed to study the ionospheric variability over a large region. The LARID consists of two high frequency (HF) coherent backscatter radars, looking toward east and west, respectively ...
Wenjie Sun, Guozhu Li, Baiqi Ning, Lianhuan Hu, Yuichi Otsuka, Guofeng Dai, Haiyong Xie, Xiukuan Zhao, Yi Li, Atsuki Shinbori, Michi Nishioka, Septi Perwitasari, Chi Wang   +12 more
wiley   +1 more source

Comparison of flow angle variations of E-region echo characteristics at VHF and HF [PDF]

, 2002
In this study, characteristics of the auroral E-region echoes at two significantly different radar frequencies of 12 and 50 MHz are compared. Considered observations were performed at the Syowa Antarctic station in March of 1997 using two HF and one VHF ...
A. S. Yukimatu, A.V. Koustov, H. Yamagishi, K. Igarashi, K. Ohtaka, N. Nishitani, N. Sato, R.A. Makarevitch, T. Ogawa   +8 more
core   +1 more source