Search Publications
Comprehensive Analysis of Coronal Mass Ejection Mass and Energy Properties Over a Full Solar Cycle
Howard, R. A.; Patsourakos, S.; Michalek, G. +3 more
The LASCO coronagraphs, in continuous operation since 1995, have observed the evolution of the solar corona and coronal mass ejections (CMEs) over a full solar cycle with high-quality images and regular cadence. This is the first time that such a data set becomes available and constitutes a unique resource for the study of CMEs. In this paper, we …
Three-dimensional Solar WIND Modeling from the Sun to Earth by a SIP-CESE MHD Model with a Six-component Grid
Wu, S. T.; Feng, Xueshang; Xiang, Changqing +3 more
The objective of this paper is to explore the application of a six-component overset grid to solar wind simulation with a three-dimensional (3D) Solar-InterPlanetary Conservation Element/Solution Element MHD model. The essential focus of our numerical model is devoted to dealing with: (1) the singularity and mesh convergence near the poles via the…
Reconnection Outflows and Current Sheet Observed with Hinode/XRT in the 2008 April 9 "Cartwheel CME" Flare
Reeves, Katharine K.; Longcope, Dana W.; Savage, Sabrina L. +2 more
Supra-arcade downflows (SADs) have been observed with Yohkoh/SXT (soft X-rays (SXR)), TRACE (extreme ultraviolet (EUV)), SOHO/LASCO (white light), SOHO/SUMER (EUV spectra), and Hinode/XRT (SXR). Characteristics such as low emissivity and trajectories, which slow as they reach the top of the arcade, are consistent with post-reconnection magnetic fl…
Coexisting Flux Rope and Dipped Arcade Sections Along One Solar Filament
Aulanier, G.; Bommier, V.; Schmieder, B. +4 more
We compute the three-dimensional magnetic field of an active region in order to study the magnetic configuration of active region filaments. The nonlinear force-free field model is adopted to compute the magnetic field above the photosphere, where the vector magnetic field was observed by THEMIS/MTR on 2005 May 27. We propose a new method to remov…
Reconstructing Coronal Mass Ejections with Coordinated Imaging and in Situ Observations: Global Structure, Kinematics, and Implications for Space Weather Forecasting
Vourlidas, Angelos; Thernisien, Arnaud; Bale, Stuart D. +4 more
We reconstruct the global structure and kinematics of coronal mass ejections (CMEs) using coordinated imaging and in situ observations from multiple vantage points. A forward modeling technique, which assumes a rope-like morphology for CMEs, is used to determine the global structure (including orientation and propagation direction) from coronagrap…
Driving Mechanism and Onset Condition of a Confined Eruption
Ding, M. D.; Schmieder, B.; Li, H. +3 more
We study a confined eruption accompanied by an M1.1 flare in solar active region (AR) NOAA 10767 on 2005 May 27, where a pre-eruptive magnetic flux rope was reported in a nonlinear force-free field (NLFFF) extrapolation. The observations show a strong writhing motion of the erupting structure, suggesting that a flux rope was indeed present and con…
Solar Meridional Circulation from Doppler Shifts of the Fe I Line at 5250 Å as Measured by the 150-foot Solar Tower Telescope at the Mt. Wilson Observatory
Ulrich, Roger K.
Doppler shifts of the Fe I spectral line at 5250 Å from the full solar disk obtained over the period 1986 to 2009 are analyzed to determine the circulation velocity of the solar surface along meridional planes. Simultaneous measurements of the Zeeman splitting of this line are used to obtain measurements of the solar magnetic field that are used t…
A Seismic Signature of a Second Dynamo?
Chaplin, William J.; Basu, Sarbani; Garcia, Rafael A. +5 more
The Sun is a variable star whose magnetic activity varies most perceptibly on a timescale of approximately 11 years. However, significant variation is also observed on much shorter timescales. We observe a quasi-biennial (2 year) signal in the natural oscillation frequencies of the Sun. The oscillation frequencies are sensitive probes of the solar…
Testing Automated Solar Flare Forecasting with 13 Years of Michelson Doppler Imager Magnetograms
Hoeksema, J. T.; Mason, J. P.
Flare occurrence is statistically associated with changes in several characteristics of the line-of-sight magnetic field in solar active regions (ARs). We calculated magnetic measures throughout the disk passage of 1075 ARs spanning solar cycle 23 to find a statistical relationship between the solar magnetic field and flares. This expansive study …
Observational Evidence of Back Reaction on the Solar Surface Associated with Coronal Magnetic Restructuring in Solar Eruptions
Liu, Chang; Wang, Haimin
Most models of solar eruptions assume that coronal field lines are anchored in the dense photosphere and thus the photospheric magnetic fields would not have rapid, irreversible changes associated with eruptions resulted from the coronal magnetic reconnection. Motivated by the recent work of Hudson et al. on quantitatively evaluating the back reac…