Search Publications
Solar Magnetic Activity and Total Irradiance Since the Maunder Minimum
Charbonneau, P.; Tapping, K. F.; Crouch, A. +3 more
We develop a model for estimating solar total irradiance since 1600 AD using the sunspot number record as input, since this is the only intrinsic record of solar activity extending back far enough in time. Sunspot number is strongly correlated, albeit nonlinearly with the 10.7-cm radio flux (F10.7), which forms a continuous record back …
CME Propagation Characteristics from Radio Observations
van Driel-Gesztelyi, L.; Culhane, J. L.; Elliott, H. A. +2 more
We explore the relationship among three coronal mass ejections (CMEs), observed on 28 October 2003, 7 November 2004, and 20 January 2005, the type II burst-associated shock waves in the corona and solar wind, as well as the arrival of their related shock waves and magnetic clouds at 1 AU. Using six different coronal/interplanetary density models, …
Multi-Spacecraft Study of the 21 January 2005 ICME. Evidence of Current Sheet Substructure Near the Periphery of a Strongly Expanding, Fast Magnetic Cloud
Dandouras, I.; Fazakerley, A. N.; Crooker, N. U. +6 more
We examine the near-Earth Interplanetary Coronal Mass Ejection (ICME) apparently related to the intense Solar Energetic Particle (SEP) event of 20 January 2005. Our purpose is to contribute to the understanding of the macroscopic structure, evolution and dynamics of the solar corona and heliosphere. Using Cluster, ACE and Wind data in the solar wi…
Evidence that Synchrotron Emission from Nonthermal Electrons Produces the Increasing Submillimeter Spectral Component in Solar Flares
Costa, J. E. R.; Silva, Adriana V. R.; Kaufmann, P. +4 more
We investigate the origin of the increasing spectra observed at submillimeter wavelengths detected in the flare on 2 November 2003 starting at 17:17 UT. This flare, classified as an X8.3 and 2B event, was simultaneously detected by RHESSI and the Solar Submillimeter Telescope (SST) at 212 and 405 GHz. Comparison of the time profiles at various wav…
How Does Large Flaring Activity from the Same Active Region Produce Oppositely Directed Magnetic Clouds?
Harra, Louise K.; Wang, Jingxiu; van Driel-Gesztelyi, Lidia +7 more
We describe the interplanetary coronal mass ejections (ICMEs) that occurred as a result of a series of solar flares and eruptions from 4 to 8 November 2004. Two ICMEs/magnetic clouds occurring from these events had opposite magnetic orientations. This was despite the fact that the major flares related to these events occurred within the same activ…
Coronal Holes and Solar Wind High-Speed Streams: II. Forecasting the Geomagnetic Effects
Veronig, Astrid M.; Temmer, Manuela; Vršnak, Bojan
We present a simple method of forecasting the geomagnetic storms caused by high-speed streams (HSSs) in the solar wind. The method is based on the empirical correlation between the coronal hole area/position and the value of the Dst index, which is established in a period of low interplanetary coronal mass ejection (ICME) activity. On average, the…
Large-Amplitude Oscillation of an Erupting Filament as Seen in EUV, Hα, and Microwave Observations
Isobe, H.; Tripathi, D.; Asai, A. +1 more
We present multiwavelength observations of a large-amplitude oscillation of a polar-crown filament on 15 October 2002, which has been reported by Isobe and Tripathi (Astron. Astrophys.449, L17, 2006). The oscillation occurred during the slow rise (≈1 km s−1) of the filament. It completed three cycles before sudden acceleration and erupt…
Solar Arcades as Possible Minimum Dissipative Relaxed States
Zank, G. P.; Dasgupta, B.; Janaki, M. S. +1 more
In this work, arcade structures are modeled to be in minimum dissipative relaxed states using a two-fluid description of the plasma. The obtained relaxed state is non-force-free in nature and appropriate to an open system with external drives. The Euler - Lagrange equations are solved in Cartesian coordinates subject to the appropriate photospheri…
Cosmic-Ray Modulation: An Empirical Relation with Solar and Heliospheric Parameters
Mavromichalaki, H.; Karalidi, T.; Paouris, E.
Long-term variations of galactic cosmic rays were compared with the behavior of various solar activity indices and heliospheric parameters during the current solar cycle. This study continues previous works where the cosmic-ray intensity for the solar cycles 20, 21, and 22 was well simulated from the linear combination of the sunspot number, the n…
Global Coronal Seismology
Ballai, I.
Following the observation and analysis of large-scale coronal-wave-like disturbances, we discuss the theoretical progress made in the field of global coronal seismology. Using simple mathematical techniques we determine average values for the magnetic field together with a magnetic map of the quiet Sun. The interaction between global coronal waves…