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Evolving Submerged Meridional Circulation Cells within the Upper Convection Zone Revealed by Ring-Diagram Analysis
Hill, Frank; Toomre, Juri; Bogart, Richard S. +3 more
Using the local helioseismic technique of ring-diagram analysis applied to Michelson Doppler Imager (MDI) Dynamics Program data from the Solar and Heliospheric Observatory, we have discovered that the meridional flow within the upper convection zone can develop additional circulation cells whose boundaries wander in latitude and depth as the solar…
Evidence of EIT and Moreton Waves in Numerical Simulations
Wu, S. T.; Chen, P. F.; Shibata, K. +1 more
Solar coronal mass ejections (CMEs) are associated with many dynamical phenomena, among which EIT waves have always been a puzzle. In this Letter MHD processes of CME-induced wave phenomena are numerically simulated. It is shown that as the flux rope rises, a piston-driven shock is formed along the envelope of the expanding CME, which sweeps the s…
Interacting Coronal Mass Ejections and Solar Energetic Particles
Kaiser, M. L.; Howard, R. A.; Gopalswamy, N. +5 more
We studied the association between solar energetic particle (SEP) events and coronal mass ejections (CMEs) and found that CME interaction is an important aspect of SEP production. Each SEP event was associated with a primary CME that is faster and wider than average CMEs and originated from west of E45°. For most of the SEP events, the primary CME…
Hot Coronal Loop Oscillations Observed by SUMER: Slow Magnetosonic Wave Damping by Thermal Conduction
Ofman, L.; Wang, Tongjiang
Recently, strongly damped Doppler shift oscillations of hot (T>6 MK) coronal loops were observed with the Solar Ultraviolet Measurement of Emitted Radiation (SUMER) spectrometer on board the Solar and Heliospheric Observatory. The oscillations are interpreted as signatures of slow-mode magnetosonic waves excited impulsively in the loops. Using …
Solar Phenomena Associated with ``EIT Waves''
Thompson, B. J.; Biesecker, D. A.; Vourlidas, A. +2 more
In an effort to understand what an ``EIT wave'' is and what its causes are, we have looked for correlations between the initiation of EIT waves and the occurrence of other solar phenomena. An EIT wave is a coronal disturbance, typically appearing as a diffuse brightening propagating across the Sun. A catalog of EIT waves, covering the period from …
Measurement of Magnetic Helicity Injection and Free Energy Loading into the Solar Corona
Kusano, K.; Sakurai, T.; Yokoyama, T. +1 more
We develop a new methodology that can determine magnetic helicity flux as well as Poynting flux across the photosphere based on magnetograph observation. By applying this method, we study the injection mechanism of magnetic helicity and magnetic free energy into the solar corona. In order to derive the helicity and energy fluxes, first the velocit…
Doppler Shift Oscillations of Hot Solar Coronal Plasma Seen by SUMER: A Signature of Loop Oscillations?
Solanki, S. K.; Curdt, W.; Innes, D. E. +2 more
We report observations of strongly damped Doppler shift oscillations detected in a flare line, Fe XIX, with the Solar Ultraviolet Measurement of Emitted Radiation spectrometer. Spectra were recorded above an active region at the western limb of the Sun, from lines with formation temperatures ranging from 0.01 to 10 MK. However, the oscillations we…
A Statistical Study of Two Classes of Coronal Mass Ejections
Moon, Y. -J.; Yang, Guo; Wang, Haimin +4 more
A comprehensive statistical study is performed to address the question of whether two classes of coronal mass ejections (CMEs) exist. A total of 3217 CME events observed by SOHO/LASCO in 1996-2000 have been analyzed. We have examined the distributions of CMEs according to speed and acceleration, respectively, and investigated the correlation betwe…
Time-Distance Helioseismology: The Forward Problem for Random Distributed Sources
Birch, A. C.; Gizon, L.
The forward problem of time-distance helioseismology is computing travel-time perturbations that result from perturbations to a solar model. We present a new and physically motivated general framework for calculations of the sensitivity of travel times to small local perturbations to solar properties, taking into account the fact that the sources …
Interaction of EIT Waves with Coronal Active Regions
Thompson, B. J.; Ofman, L.
Large-scale coronal waves associated with flares were first observed by the Solar and Heliospheric Observatory (SOHO) Extreme ultraviolet Imaging Telescope (EIT). We present the first three-dimensional MHD modeling of the interaction of the EIT waves with active regions and the possibility of destabilization of an active region by these waves. The…