Search Publications
Highly relativistic radiation belt electron acceleration, transport, and loss: Large solar storm events of March and June 2015
Baker, D. N.; Kanekal, S. G.; Zhao, H. +12 more
Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (storm time ring current index) value reaching -223 nT. On 22 June 2015 another strong storm (Dst reaching -204 nT) was recorded. These two storms each produced almost total loss of radiation b…
A model for stealth coronal mass ejections
Luhmann, J. G.; Li, Y.; Masson, S. +4 more
Stealth coronal mass ejections (CMEs) are events in which there are almost no observable signatures of the CME eruption in the low corona but often a well-resolved slow flux rope CME observed in the coronagraph data. We present results from a three-dimensional numerical magnetohydrodynamics (MHD) simulation of the 1-2 June 2008 slow streamer blowo…
Predicting the amplitude and hemispheric asymmetry of solar cycle 25 with surface flux transport
Hathaway, David H.; Upton, Lisa A.
Evidence strongly indicates that the strength of the Sun's polar fields near the time of a sunspot cycle minimum determines the strength of the following solar activity cycle. We use our Advective Flux Transport code, with flows well constrained by observations, to simulate the evolution of the Sun's polar magnetic fields from early 2016 to the en…
Time-dependent magnetohydrodynamic simulations of the inner heliosphere
Merkin, V. G.; Lyon, J. G.; Lario, D. +2 more
This paper presents results from a simulation study exploring heliospheric consequences of time-dependent changes at the Sun. We selected a 2 month period in the beginning of year 2008 that was characterized by very low solar activity. The heliosphere in the equatorial region was dominated by two coronal holes whose changing structure created temp…
On the propagation of a geoeffective coronal mass ejection during 15-17 March 2015
Webb, D. F.; Wang, Yuming; Shen, Fang +11 more
The largest geomagnetic storm so far, called 2015 St. Patrick's Day event, in the solar cycle 24 was produced by a fast coronal mass ejection (CME) originating on 15 March 2015. It was an initially west-oriented CME and expected to only cause a weak geomagnetic disturbance. Why did this CME finally cause such a large geomagnetic storm? We try to f…
Global magnetohydrodynamic simulation of the 15 March 2013 coronal mass ejection event—Interpretation of the 30-80 MeV proton flux
Wu, S. T.; Vourlidas, Angelos; Wu, Chin-Chun +4 more
The coronal mass ejection (CME) event on 15 March 2013 is one of the few solar events in Cycle 24 that produced a large solar energetic particle (SEP) event and severe geomagnetic activity. Observations of SEP from the ACE spacecraft show a complex time-intensity SEP profile that is not easily understood with current empirical SEP models. In this …
Energy dependence of SEP electron and proton onset times
St. Cyr, O. C.; Gopalswamy, N.; Mäkelä, P. +1 more
We study the large solar energetic particle (SEP) events that were detected by GOES in the >10 MeV energy channel during December 2006 to March 2014. We derive and compare solar particle release (SPR) times for the 0.25-10.4 MeV electrons and 10-100 MeV protons for the 28 SEP events. In the study, the electron SPR times are derived with the tim…
Comparative ionospheric impacts and solar origins of nine strong geomagnetic storms in 2010-2015
Wood, Brian E.; Wang, Yi-Ming; Lean, Judith L. +1 more
For nine of the strongest geomagnetic storms in solar cycle 24 we characterize, quantify, and compare the impacts on ionospheric total electron content (TEC) and the U.S. Wide Area Augmentation System (WAAS) with the heliospheric morphology and kinematics of the responsible coronal mass ejections (CMEs) and their solar source regions. Regional TEC…
CME flux rope and shock identifications and locations: Comparison of white light data, Graduated Cylindrical Shell model, and MHD simulations
St. Cyr, O. C.; Gopalswamy, N.; Cairns, Iver H. +2 more
Coronal mass ejections (CMEs) are major transient phenomena in the solar corona that are observed with ground-based and spacecraft-based coronagraphs in white light or with in situ measurements by spacecraft. CMEs transport mass and momentum and often drive shocks. In order to derive the CME and shock trajectories with high precision, we apply the…
Coronal magnetic field profiles from shock-CME standoff distances
Gopalswamy, N.; Cairns, Iver H.; Yashiro, S. +1 more
Coronagraphs observe coronal mass ejections (CMEs) and driven shocks in white light images. From these observations the shock's speed and the shock's standoff distance from the CME's leading edge can be derived. Using these quantities, theoretical relationships between the shock's Alfvénic Mach number MA and standoff distance, and empirical radial…