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Long-Term Evolution of the Solar Corona Using PROBA2 Data
Berghmans, David; West, Matthew J.; Mierla, Marilena +5 more
We use The Sun Watcher with Active Pixel System detector and Image Processing (SWAP) imager onboard the Project for Onboard Autonomy 2 (PROBA2) mission to study the evolution of large-scale EUV structures in the solar corona observed throughout Solar Cycle 24 (from 2010 to 2019). We discuss the evolution of the on-disk coronal features and at diff…
On the Relationship Between the Transit Time of ICMEs and Strength of the Initiated Geomagnetic Storms
Chertok, I. M.
More than 140 isolated non-recurrent geomagnetic storms (GMSs) of various intensities from extreme to weak are considered; these are reliably identified with solar eruptive sources (coronal mass ejections, CMEs). The analysis aims to obtain a possibly complete picture of the relationship between the transit time of propagation of CMEs and interpla…
Relationships between Interplanetary Coronal Mass Ejection Characteristics and Geoeffectiveness in the Declining Phase of Solar Cycles 23 and 24
Moon, Y. -J.; Shanmugaraju, A.; Lawrance, M. Bendict
In this paper, we have examined the relationships between the characteristics of interplanetary coronal mass ejections (ICMEs) and geoeffectiveness in the declining phase of Solar Cycles 23 and 24. We discuss the results in comparison with those of the rising phase. Major results of this study are as follows: The ICMEs in the declining phase of Cy…
Statistical Analysis of Asymmetric Sunspot Decay Observed by Hinode
Imada, Shinsuke; Kato, Shota; Fujiyama, Masashi
We statistically studied the transport of magnetic flux in and around sunspots using a magnetic-element tracking technique to investigate whether sunspot-decay processes are isotropic. Using this method, we detected moving magnetic features (MMFs). The observed radius of an MMFs region was approximately 1.7 times the sunspot radius; furthermore, t…
Magnetic Flux Emergence in a Coronal Hole
Denker, Carsten; Temmer, Manuela; Veronig, Astrid +13 more
A joint campaign of various space-borne and ground-based observatories, comprising the Japanese Hinode mission (Hinode Observing Plan 338, 20 - 30 September 2017), the GREGOR solar telescope, and the Vacuum Tower Telescope (VTT), investigated numerous targets such as pores, sunspots, and coronal holes. In this study, we focus on the coronal hole r…
Radio Sounding Measurements of the Solar Corona Using Giant Pulses of the Crab Pulsar in 2018
Tokumaru, Munetoshi; Terasawa, Toshio; Sekido, Mamoru +2 more
Observations of the Crab pulsar at 327 MHz were made at the Toyokawa Observatory of the Institute for Space-Earth Environmental Research, during the solar occultation in mid-June 2018 to investigate the coronal plasma density in the weak sunspot cycle, Cycle 24. The dispersion measurements (DMs) were determined using giant pulses detected from obs…
Magnetic and Velocity Field Topology in Active Regions of Descending Phase of Solar Cycle 23
Maurya, R. A.; Ambastha, A.
We analyze the topology of photospheric magnetic fields and sub-photospheric flows of several active regions (ARs) that are observed during the peak to descending phase of Solar Cycle 23. Our analysis shows clear evidence of hemispheric preferences in all the topological parameters such as the magnetic, current and kinetic helicities, and the `cur…
On the Emission Region of Type II Radio Bursts in Interplanetary Shock Fronts
Aguilar-Rodriguez, E.; Corona-Romero, P.
We analyze Type II radio emissions observed by the Radio and Plasma Waves instrument onboard Wind to determine the emission region in shock fronts, using the blast wave reconstruction technique. Our results suggest that the processes of emission of a Type II radio burst occur not only in the upstream region of the shock, i.e. the region that prece…
Spectral Analysis of Forbush Decreases Using a New Yield Function
Livada, M.; Mavromichalaki, H.
The Forbush decreases of the cosmic ray intensity observed on 24 December 2014 and on 8 September 2017 were chosen for cosmic ray spectral analysis. At first an analytical study of the solar and geomagnetic parameters of these events was carried out due to the fact that both are typical cosmic ray events. Hourly cosmic ray data of the neutron moni…
A Multiwavelength Analysis of the Long-duration Flare Observed on 15 April 2002
Mrozek, Tomasz; Kepa, Anna; Sylwester, Barbara +2 more
We present a multiwavelength analysis of the long-duration flare observed on 15 April 2002 (soft X-ray peak time at 03:55 UT, SOL2002-04-15T03:55). This flare occurred on the disk (S15W01) in NOAA 9906 and was observed by a number of space instruments including the Extreme-Ultraviolet Imaging Telescope on the Solar and Heliospheric Observatory (SO…