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Variation in the Width of Transition Region Network Boundaries
Raju, K. P.
The transition region network seen in solar extreme ultraviolet (EUV) lines is the extension of the chromospheric network. The network appears as an irregular web-like pattern over the solar surface outside active regions. The average width of transition region network boundaries is obtained from the two-dimensional autocorrelation function of SOl…
Temporal Evolution of Solar Energetic Particle Spectra
Dalla, Silvia; Doran, Donald J.
During solar flares and coronal mass ejections, Solar Energetic Particles (SEPs) may be released into the interplanetary medium and near-Earth locations. The energy spectra of SEP events at 1 AU are typically averaged over the entire event or studied in a few snapshots. In this article we analyze the time evolution of the energy spectra of four la…
Classification of CMEs Based on Their Dynamics
Michalek, G.; Nicewicz, J.
A large set of coronal mass ejections CMEs (6621) has been selected to study their dynamics seen with the Large Angle and Spectroscopic Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO) field of view (LFOV). These events were selected based on having at least six height-time measurements so that their dynamic properties, in…
A Possible Cause of the Diminished Solar Wind During the Solar Cycle 23 - 24 Minimum
Wu, Chin-Chun; Liou, Kan
Interplanetary magnetic field and solar wind plasma density observed at 1 AU during Solar Cycle 23 - 24 (SC-23/24) minimum were significantly smaller than those during its previous solar cycle (SC-22/23) minimum. Because the Earth's orbit is embedded in the slow wind during solar minimum, changes in the geometry and/or content of the slow wind reg…
Propagation of Solar Energetic Particles During Multiple Coronal Mass Ejection Events
Valtonen, Eino; Pohjolainen, Silja; Al-Hamadani, Firas
We study solar energetic particle (SEP) events during multiple solar eruptions. The analysed sequences, on 24 - 26 November 2000, 9 - 13 April 2001, and 22 - 25 August 2005, consisted of halo-type coronal mass ejections (CMEs) that originated from the same active region and were associated with intense flares, EUV waves, and interplanetary (IP) ra…
Temporal Offsets Between Maximum CME Speed Index and Solar, Geomagnetic, and Interplanetary Indicators During Solar Cycle 23 and the Ascending Phase of Cycle 24
Özgüç, A.; Kilcik, A.; Georgieva, K. +1 more
On the basis of a morphological analysis of yearly values of the maximum coronal mass ejection (CME) speed index, the sunspot number and total sunspot area, sunspot magnetic field, and solar flare index, the solar wind speed and interplanetary magnetic field strength, and the geomagnetic Ap and Dst indices, we point out the p…
LYRA Mid-Term Periodicities
Dammasch, I. E.; Dominique, M.; Wauters, L.
The spectra of the PROBA2/LYRA data, similarly to every other solar time series, show predominant periodicities that can be of solar or instrumental origin. In this article, we compare the main periodicities characterizing the LYRA spectrum to those found in the sunspot number, in the 10.7 cm flux, in an X-ray flare index, and in the sunspot area …
Ensemble Modeling of CMEs Using the WSA-ENLIL+Cone Model
Jian, L. K.; Odstrcil, D.; Zheng, Y. +8 more
Ensemble modeling of coronal mass ejections (CMEs) provides a probabilistic forecast of CME arrival time that includes an estimation of arrival-time uncertainty from the spread and distribution of predictions and forecast confidence in the likelihood of CME arrival. The real-time ensemble modeling of CME propagation uses the Wang-Sheeley-Arge (WSA…
Relationship between Solar Energetic Particles and Properties of Flares and CMEs: Statistical Analysis of Solar Cycle 23 Events
Dalla, S.; Malandraki, O.; Tziotziou, K. +5 more
A statistical analysis of the relationship between solar energetic particles (SEPs) and properties of solar flares and coronal mass ejections (CMEs) is presented. SEP events during Solar Cycle 23 are selected that are associated with solar flares originating in the visible hemisphere of the Sun and that are at least of magnitude M1. Taking into ac…
Flare-CME Models: An Observational Perspective (Invited Review)
Aulanier, G.; Vršnak, B.; Schmieder, B.
Eruptions, flares, and coronal mass ejection (CMEs) are due to physical phenomena mainly driven by an initially force-free current-carrying magnetic field. We review some key observations relevant to the current theoretical trigger mechanisms of the eruption and to the energy release via reconnection. Sigmoids observed in X-rays and UV, as well as…