Search Publications
Investigation of the negative ionospheric response of the 8 September 2017 geomagnetic storm over the European sector
Oikonomou, Christina; Haralambous, Haris; Paul, Ashik +4 more
In this study, we investigate the negative ionospheric response over the European sector during two storms that took place on 8 September 2017, primarily, by exploiting observations over ten European locations. The spatial and temporal variations of TEC, foF2 and hmF2 ionospheric characteristics are examined with the aim to explain the physical me…
Gaia astrometric and photometric study of open clusters Dolidze 18 & Ruprecht 70
Tadross, A. L.; Hendy, Y. H.
Here, we conducted a photometric and astrometric study of two open stellar clusters Dolidze 18 and Ruprecht 70, which have not been photometrically studied before. The most important thing for using Gaia (DR2) database lies in the positions, parallax, and proper motions, which make us split cluster members from the field ones and get precise astro…
Flux emergence and generation of flare-productive active regions
Toriumi, Shin
Solar flares and coronal mass ejections are among the most prominent manifestations of the magnetic activity of the Sun. The strongest events of them tend to occur in active regions (ARs) that are large, complex, and dynamically evolving. However, it is not clear what the key observational features of such ARs are, and how these features are produ…
The transport of galactic cosmic rays in heliosphere: The HELMOD model compared with other commonly employed solar modulation models
Gervasi, M.; Rancoita, P. G.; Boschini, M. J. +2 more
HELMOD model allows one to describe how solar modulation affects the propagation of galactic cosmic rays (GCRs) through the heliosphere by solving the Parker transport equation. HELMOD provides modulated spectra for protons and nuclei during high and low solar activity periods, in the inner and outer heliosphere, at Earth location and outside the …
Dielectric characterization and polarimetric analysis of lunar north polar crater Hermite-A using Chandrayaan-1 Mini-SAR, Lunar Reconnaissance Orbiter (LRO) Mini-RF, and Chandrayaan-2 DFSAR data
Chauhan, Prakash; Singh, Awinash; Sharma, Aanchal +5 more
Studies of the lunar surface from Synthetic Aperture Radar (SAR) data have played a prominent role in the exploration of the lunar surface in recent times. This study uses data from SAR sensors from three Moon missions: Chandrayaan-1 Mini-SAR, Lunar Reconnaissance Orbiter (LRO) Mini-RF and Chandrayaan-2 Dual Frequency Synthetic Aperture Radar (DFS…
Solar and interplanetary events that drove two CIR-related geomagnetic storms of 1 June 2013 and 7 October 2015, and their ionospheric responses at the American and African equatorial ionization Anomaly regions
Akala, A. O.; Amaechi, P. O.; Simi, K. G. +3 more
This study investigates the sequence of solar and interplanetary events that drove the 1 June 2013 and October 2015 geomagnetic storms and how the American (68°-78oE) and African (32°-42oE) Equatorial Ionization Anomaly (EIA) regions responded to them. We constructed the EIA structures by using Total Electron Content (TEC) an…
Ionospheric total electron content anomaly possibly associated with the April 4, 2010 Mw7.2 Baja California earthquake
Zhou, Chen; Liu, Jing; Wang, Wenbin +2 more
Identifying ionospheric disturbances potentially related to an earthquake is a challenging work. Based on the ionospheric total electron content (TEC) data from the madrigal database at the Haystack Observatory, Massachusetts Institute of Technology, a new decomposition and nonlinear fitting method has been developed and applied in this work to ex…
A detailed comparison of techniques used to model drift in numerical cosmic ray modulation models
Ferreira, S. E. S.; Engelbrecht, N. Eugene; Mohlolo, S. T.
Drifts have long been known to play a significant role in the transport and modulation of galactic cosmic rays (GCRs), occurring due to gradients in, as well as the curvature of, the heliospheric magnetic field (HMF). GCRs also drift along the wavy current sheet, a structure separating regions of opposite HMF polarity. Furthermore, the influence o…
Complex network view to solar flare asymmetric activity
Taran, Somayeh; Khodakarami, Edris; Safari, Hossein
Asymmetric behavior of the solar hemispheres is an essential aspect of the activity. This paper uses a complex network approach to study the solar flare asymmetric activity in two hemispheres. We construct a network based on the locations and flare flux (GOES flux classification) from 2008 December to 2019 December for 4033 and 4725 flares on the …
Enthalpy-based modeling of tomographically reconstructed quiet-Sun coronal loops
Mandrini, C. H.; Vásquez, A. M.; Mac Cormack, C. +2 more
The structure of the solar corona is made of magnetic flux tubes or loops. Due to the lack of contrast with their environment, observing and studying coronal loops in the quiet Sun is extremely difficult. In this work we use a differential emission measure tomographic (DEMT) technique to reconstruct, from a series of EUV images covering an entire …