Search Publications
Coronal Magnetic Field Evolution from 1996 to 2012: Continuous Non-potential Simulations
Yeates, A. R.
Coupled flux transport and magneto-frictional simulations are extended to simulate the continuous magnetic-field evolution in the global solar corona for over 15 years, from the start of Solar Cycle 23 in 1996. By simplifying the dynamics, our model follows the build-up and transport of electric currents and free magnetic energy in the corona, off…
Abundance Enhancements in Impulsive Solar Energetic-Particle Events with Associated Coronal Mass Ejections
Reames, Donald V.; Kahler, Stephen W.; Cliver, Edward W.
We study the abundances of the elements He through Pb in Fe-rich impulsive solar energetic-particle (SEP) events with measurable abundances of ions with atomic number Z>2 observed on the Wind spacecraft, and their relationship with coronal mass ejections (CMEs) observed by the Large Angle and Spectrometric Coronagraph (LASCO) onboard the Solar …
Time-Dependent Modulation of Cosmic Rays in the Heliosphere
Ferreira, S. E. S.; Potgieter, M. S.; Manuel, R.
The time-dependent modulation of galactic cosmic rays in the heliosphere is studied by computing intensities using a time-dependent modulation model. By introducing recent theoretical advances in the transport coefficients in the model, computed intensities are compared with Voyager 1, International Monitoring Platform (IMP) 8, and Ulysses proton …
Solar Sources of Interplanetary Coronal Mass Ejections During the Solar Cycle 23/24 Minimum
Mierla, M.; Zhukov, A. N.; Rodriguez, L. +3 more
We examine solar sources for 20 interplanetary coronal mass ejections (ICMEs) observed in 2009 in the near-Earth solar wind. We performed a detailed analysis of coronagraph and extreme ultraviolet (EUV) observations from the Solar Terrestrial Relations Observatory (STEREO) and Solar and Heliospheric Observatory (SOHO). Our study shows that the cor…
Statistical Analysis of Large-Scale EUV Waves Observed by STEREO/EUVI
Temmer, M.; Veronig, A. M.; Vršnak, B. +3 more
We statistically analyzed the kinematical evolution and wave pulse characteristics of 60 strong large-scale EUV wave events that occurred during January 2007 to February 2011 with the STEREO twin spacecraft. For the start velocity, the arithmetic mean is 312±115 km s−1 (within a range of 100 - 630 km s−1). For the mean (linea…
Solar Energetic Particles and Associated EIT Disturbances in Solar Cycle 23
Temmer, M.; Veronig, A.; Klein, K. -L. +3 more
We explore the link between solar energetic particles (SEPs) observed at 1 AU and large-scale disturbances propagating in the solar corona, named after the Extreme ultraviolet Imaging Telescope (EIT) as EIT waves, which trace the lateral expansion of a coronal mass ejection (CME). A comprehensive search for SOHO/EIT waves was carried out for 179 S…
Are There Different Populations of Flux Ropes in the Solar Wind?
Démoulin, P.; Dasso, S.; Janvier, M.
Flux ropes are twisted magnetic structures that can be detected by in-situ measurements in the solar wind. However, different properties of detected flux ropes suggest different types of flux-rope populations. As such, are there different populations of flux ropes? The answer is positive and is the result of the analysis of four lists of flux rope…
Using Polar Coronal Hole Area Measurements to Determine the Solar Polar Magnetic Field Reversal in Solar Cycle 24
Karna, N.; Hess Webber, S. A.; Pesnell, W. D.
An analysis of solar polar coronal hole (PCH) areas since the launch of the Solar Dynamics Observatory (SDO) shows how the polar regions have evolved during Solar Cycle 24. We present PCH areas from mid-2010 through 2013 using data from the Atmospheric Imager Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) instruments onboard SDO. Our an…
The First Ground-Level Enhancement of Solar Cycle 24 on 17 May 2012 and Its Real-Time Detection
Mavromichalaki, H.; Papaioannou, A.; Souvatzoglou, G. +2 more
Ground-level enhancements (GLEs) are defined as sudden increases in the recorded intensity of cosmic-ray particles, usually by neutron monitors (NMs). In this work we present a time-shifting analysis (TSA) for the first arriving particles that were detected at Earth by NMs. We also present an automated real-time GLE alert that has been developed a…
Very Fast and Accurate Azimuth Disambiguation of Vector Magnetograms
Anfinogentov, S. A.; Rudenko, G. V.
We present a method for fast and accurate azimuth disambiguation of vector magnetogram data regardless of the location of the analyzed region on the solar disk. The direction of the transverse field is determined with the principle of minimum deviation of the field from the reference (potential) field. The new disambiguation (NDA) code is examined…