Search Publications
Element Abundances: A New Diagnostic for the Solar Wind
Vourlidas, Angelos; Cranmer, Steven R.; Wood, Brian E. +11 more
We examine the different element abundances exhibited by the closed loop solar corona and the slow speed solar wind. Both are subject to the first ionization potential (FIP) effect, the enhancement in coronal abundance of elements with FIP below 10 eV (e.g., Mg, Si, Fe) with respect to high-FIP elements (e.g., O, Ne, Ar), but with subtle differenc…
Connecting the Properties of Coronal Shock Waves with Those of Solar Energetic Particles
Vourlidas, Angelos; Kouloumvakos, Athanasios; Rouillard, Alexis P. +5 more
We develop and exploit a new catalog of coronal pressure waves modeled in 3D to study the potential role of these waves in accelerating solar energetic particles (SEPs) measured in situ. Our sample comprises modeled shocks and SEP events detected during solar cycle 24 observed over a broad range of longitudes. From the 3D reconstruction of shock w…
Validation of the Alfvén Wave Solar Atmosphere Model (AWSoM) with Observations from the Low Corona to 1 au
van der Holst, Bart; Lamy, Philippe; Vásquez, Alberto M. +9 more
We perform a validation study of the latest version of the Alfvén Wave Solar atmosphere Model (AWSoM) within the Space Weather Modeling Framework. To do so, we compare the simulation results of the model with a comprehensive suite of observations for Carrington rotations representative of the solar minimum conditions extending from the solar coron…
A Comparison of Flare Forecasting Methods. III. Systematic Behaviors of Operational Solar Flare Forecasting Systems
Leka, K. D.; Gallagher, Peter T.; Murray, Sophie A. +21 more
A workshop was recently held at Nagoya University (2017 October 31-November 2), sponsored by the Center for International Collaborative Research, at the Institute for Space-Earth Environmental Research, Nagoya University, Japan, to quantitatively compare the performance of today’s operational solar flare forecasting facilities. Building upon Paper…
Why Do Torus-unstable Solar Filaments Experience Failed Eruptions?
Wang, Yuming; Zhuang, Bin; Liu, Lijuan +5 more
We study the magnetic field and 3D configuration of 16 filament eruptions during 2010 July-2013 February in order to investigate the factors that control the success and/or failure of solar eruptions. All of these events, i.e., eruptions that failed to be ejected and become coronal mass ejections, have filament maximum heights exceeding 100 Mm. Th…
Heliospheric Evolution of Magnetic Clouds
Möstl, C.; Farrugia, C. J.; Temmer, M. +7 more
The interplanetary evolution of 11 magnetic clouds (MCs) recorded by at least two radially aligned spacecraft is studied. The in situ magnetic field measurements are fitted to a cylindrically symmetric Gold-Hoyle force-free uniform-twist flux-rope configuration. The analysis reveals that in a statistical sense, the expansion of the studied MCs is …
In Situ Measurements of the Variable Slow Solar Wind near Sector Boundaries
Davies, J. A.; Lavraud, B.; Kilpua, E. +2 more
The release of density structures at the tip of the coronal helmet streamers, likely as a consequence of magnetic reconnection, contributes to the mass flux of the slow solar wind (SSW). In situ measurements in the vicinity of the heliospheric plasma sheet of the magnetic field, protons, and suprathermal electrons reveal details of the processes a…
Properties of Slow Magnetoacoustic Oscillations of Solar Coronal Loops by Multi-instrumental Observations
Moon, Y. -J.; Nakariakov, V. M.; Kumar, P. +3 more
Rapidly decaying oscillations of the thermal emission detected in the decay phase of solar and stellar flares are usually interpreted as standing or sloshing (reflecting) slow magnetoacoustic oscillations. We determine the scalings of the oscillation periods, damping times, and amplitudes with the temperature, considering both standing and sloshin…
Geometry, Kinematics, and Heliospheric Impact of a Large CME-driven Shock in 2017 September
Liu, Ying D.; Zhao, Xiaowei; Zhu, Bei
A powerful coronal mass ejection (CME) occurred on 2017 September 10 near the end of the declining phase of the historically weak solar cycle 24. We obtain new insights concerning the geometry and kinematics of CME-driven shocks in relation to their heliospheric impacts from the optimal, multispacecraft observations of the eruption. The shock, whi…
Can an Unobserved Concentration of Magnetic Flux Above the Poles of the Sun Resolve the Open Flux Problem?
Downs, Cooper; Riley, Pete; Linker, Jon A. +3 more
Global models of the extended solar corona, driven by observed photospheric magnetic fields, generally cannot reproduce the amplitude of the measured interplanetary magnetic field at 1 au (or elsewhere in the heliosphere), often underestimating it by a factor of two or more. Some modelers have attempted to resolve this “open flux” problem by adjus…