Search Publications
Deflected propagation of a coronal mass ejection from the corona to interplanetary space
Wang, Yuming; Shen, Fang; Shen, Chenglong +2 more
Among various factors affecting the space weather effects of a coronal mass ejection (CME), its propagation trajectory in the interplanetary space is an important one determining whether and when the CME will hit the Earth. Many direct observations have revealed that a CME may not propagate along a straight trajectory in the corona, but whether or…
Evolution of the 12 July 2012 CME from the Sun to the Earth: Data-constrained three-dimensional MHD simulations
Hess, Phillip; Wang, Yuming; Shen, Fang +5 more
The dynamic process of coronal mass ejections (CMEs) in the heliosphere provides us the key information for evaluating CMEs' geoeffectiveness and improving the accurate prediction of CME-induced shock arrival time at the Earth. We present a data-constrained three-dimensional (3-D) magnetohydrodynamic (MHD) simulation of the evolution of the CME in…
Wide longitudinal distribution of interplanetary electrons following the 7 February 2010 solar event: Observations and transport modeling
Dresing, N.; Heber, B.; Dröge, W. +2 more
We analyze 65-105 keV electrons in the 7 February 2010 solar electron event observed simultaneously by STEREO-A, STEREO-B, and ACE. A method to reconstruct the full-electron pitch angle distributions from the four Solar Electron and Proton Telescope sensors on STEREO-A/B and the Solar Electron and Proton Telescope instrument on ACE in the energy r…
A "breathing" source surface for cycles 23 and 24
Sun, X.; Arden, W. M.; Norton, A. A.
The potential field source surface (PFSS) model is used to represent the large-scale geometry of the solar coronal magnetic fields. The height of the source surface in this model can be taken as a free parameter. Previous work suggests that varying the source surface height during periods of solar minimum yields better agreement between PFSS model…
Full-halo coronal mass ejections: Arrival at the Earth
Wang, Yuming; Shen, Chenglong; Wang, S. +3 more
A geomagnetic storm is mainly caused by a frontside coronal mass ejection (CME) hitting the Earth and then interacting with the magnetosphere. However, not all frontside CMEs can hit the Earth. Thus, which CMEs hit the Earth and when they do so are important issues in the study and forecasting of space weather. In our previous work, the deprojecte…
The solar meridional circulation and sunspot cycle variability
Hathaway, D. H.; Upton, L.
We have measured the meridional motions of the magnetic elements in the Sun's surface layers since 1996 and find systematic and substantial variations. In general the meridional flow speed is fast at cycle minima and slow at cycle maxima. We find that these systematic variations are characterized by a weakening of the meridional flow on the polewa…
Variation of the solar magnetic flux spectrum during solar cycle 23
Wang, J. X.; Jin, C. L.
By using the unique database of Solar and Heliospheric Observatory/Michelson Doppler Imager full disk magnetograms from September 1996 to January 2011, covering the entire solar cycle 23, we analyze the time-variability of the solar magnetic flux spectrum and study the properties of extended minimum of cycle 23. We totally identify 11.5 million ma…
Comparing the solar minima of cycles 22/23 and 23/24: The view from LASCO white light coronal images
Llebaria, A.; Lamy, P.; Floyd, O. +1 more
The Large Angle and Spectrometric Coronagraph LASCO-C2 aboard SOHO has now completed 17 years (1996-2012) of quasi-continuous white-light imaging of the corona from 2.2 to 6.5 solar radii, thus allowing an unprecedented view of its evolution over a solar cycle and a half including the minima of solar cycles 22/23 and 23/24. The corrected and calib…
Influence of interplanetary coronal mass ejections on the peak intensity of solar energetic particle events
Lario, D.; Karelitz, A.
We study whether the presence of coronal mass ejections (CMEs) in interplanetary space (ICMEs) affects the maximum intensity of solar energetic particle (SEP) events. We compute the maximum intensity of 175-315 keV electron and 9-15, 15-40, and 40-80 MeV proton fluxes measured during the prompt component of 147 western SEP events observed near Ear…
Magnetic clouds and origins in STEREO era
Luhmann, J. G.; Kilpua, E. K. J.; Lynch, B. J. +1 more
When a coronal mass ejection (CME) encounters the Earth, the Earth's electromagnetic environment is disturbed, especially when it is a magnetic cloud (MC) with enhanced, steady, and long-lasting southward field. The speed and the magnetic field of an MC are the two important properties for its geoeffectiveness. The correspondence between a CME and…