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Major Solar Energetic Particle Events of Solar Cycles 22 and 23: Intensities Close to the Streaming Limit
Lario, D.; Aran, A.; Decker, R. B.
It has been argued that the highest intensities measured near 1 AU during large solar energetic particle events occur in association with the passage of interplanetary shocks driven by coronal mass ejections, whereas the intensities measured early in the events (known as the prompt component) are bounded by a maximum intensity plateau known as the…
Multi-spacecraft Observations of CIR-Associated Ion Increases During the Ulysses 2007 Ecliptic Crossing
Dresing, Nina; Heber, Bernd; Gómez-Herrero, Raúl +3 more
The period between 21 June and 8 October, 2007 (Carrington rotations 2058 to 2061), comprising the Ulysses ecliptic plane crossing, was characterized by low solar activity. Excluding the small solar energetic particle events observed during July, the ion increases observed in the inner heliosphere between 100 keV/n and 10 MeV/n were associated wit…
Sources of Solar Total Irradiance Variations
Withbroe, George L.
The daily images and magnetograms acquired by MDI are a rich source of information about the contributions of different types of solar regions to variations in the total solar irradiance (TSI). These data have been used to determine the temporal variation of the MDI irradiance, the mean intensity of the solar disk in the continuum at 676.8 nm. The…
Evaluation of a Selected Case of the Minimum Dissipative Rate Method for Non-Force-Free Solar Magnetic Field Extrapolations
Gary, G. Allen
The minimum dissipative rate (MDR) method for deriving a coronal non-force-free magnetic field solution is partially evaluated. These magnetic field solutions employ a combination of three linear (constant-α) force-free-field solutions with one being a potential field (i.e., α=0). The particular case of the solutions where the other two α's are of…
Cyclical Behavior of Coronal Mass Ejections
Li, K. J.; Gao, P. X.; Li, Q. X. +2 more
With the use of coronal mass ejections (CMEs) observed by the Large Angle and Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO) from January 1996 through December 2005, it is found that, for the cyclical activity of CMEs, there is surprisingly no equatorward drift at low latitudes (thus, no "butterfly diagram"…
Study of Ribbon Separation and Magnetic Reconnection Rates in a Two-Ribbon Flare
Zhang, H.; Wang, H.; Xie, W.
In this paper, we present a study of the correlation between the speed of flare ribbon separation and the magnetic flux density during the 10 April 2001 solar flare. The study includes the section of the neutral line containing the flare core and its peripheral area. This event shows clear two-ribbon structure and inhomogeneous magnetic fields alo…
Inferring Small-Scale Flatfields from Solar Rotation
Schou, J.; Wachter, R.
We present a method to infer small-scale flatfields for imaging solar instruments using only regular-observation intensity images with a fixed field of view. The method is related to the flatfielding method developed by Kuhn, Lin, and Loranz (Publ. Astron. Soc. Pac. 103, 1097 - 1108, 1991), but does not require image offsets. Instead, it takes adv…
The Impact of Geometry on Observations of CME Brightness and Propagation
Webb, D. F.; Howard, R. A.; Vourlidas, A. +2 more
Coronal mass ejections (CMEs) have a significant impact on space weather and geomagnetic storms and so have been the subject of numerous studies. Most CME observations have been made while these events are near the Sun (e.g., SOHO/LASCO). Recent data from the Coriolis/SMEI and STEREO/SECCHI-HI instruments have imaged CMEs farther into the heliosph…
Interpreting Helioseismic Structure Inversion Results of Solar Active Regions
Basu, Sarbani; Li, Linghuai; Lin, Chia-Hsien
Helioseismic techniques such as ring-diagram analysis have often been used to determine the subsurface structural differences between solar active and quiet regions. Results obtained by inverting the frequency differences between the regions are usually interpreted as the sound-speed differences between them. These in turn are used as a measure of…
Lifetimes of High-Degree p Modes in the Quiet and Active Sun
Hill, F.; Kholikov, S.; Burtseva, O. +1 more
We study variations of the lifetimes of high-ℓ solar p modes in the quiet and active Sun with the solar activity cycle. The lifetimes in the degree range ℓ=300 - 600 and ν=2.5 - 4.5 mHz were computed from SOHO/MDI data in an area including active regions and quiet Sun using the time - distance technique. We applied our analysis to the data in four…