Search Publications
Geoeffectiveness of Coronal Mass Ejections in the SOHO Era
Rodriguez, L.; Vršnak, B.; Veronig, A. +6 more
The main objective of the study is to determine the probability distributions of the geomagnetic Dst index as a function of the coronal mass ejection (CME) and solar flare parameters for the purpose of establishing a probabilistic forecast tool for the intensity of geomagnetic storms. We examined several CME and flare parameters as well as the eff…
Improved Helioseismic Analysis of Medium-ℓ Data from the Michelson Doppler Imager
Schou, Jesper; Larson, Timothy P.
We present a comprehensive study of one method for measuring various parameters of global modes of oscillation of the Sun. Using velocity data taken by the Michelson Doppler Imager (MDI), we analyze spherical harmonic degrees ℓ ≤300 . Both current and historical methodologies are explained, and the various differences between the two are investiga…
Relations Between Microwave Bursts and Near-Earth High-Energy Proton Enhancements and Their Origin
Grechnev, V. V.; Chertok, I. M.; Kiselev, V. I. +1 more
We further study the relations between parameters of bursts at 35 GHz recorded with the Nobeyama Radio Polarimeters during 25 years and solar proton events (Grechnev et al. in Publ. Astron. Soc. Japan65, S4, 2013a). Here we address the relations between the microwave fluences at 35 GHz and near-Earth proton fluences above 100 MeV to find informati…
On the Statistical Relationship Between CME Speed and Soft X-Ray Flux and Fluence of the Associated Flare
Klein, K. -L.; Salas-Matamoros, C.
Observation and theory both reveal a close relationship between the kinematics of coronal mass ejections (CMEs) and the thermal energy release traced by the related soft X-ray (SXR) emission. A major problem of empirical studies of this relationship is the distortion of the CME speed by the projection effect in the coronagraphic measurements. We p…
Mg II Lines Observed During the X-class Flare on 29 March 2014 by the Interface Region Imaging Spectrograph
Heinzel, P.; Liu, W.; Kleint, L. +1 more
Mg II lines represent one of the strongest emissions from the chromospheric plasma during solar flares. In this article, we studied the Mg II lines observed during the X1 flare on 29 March 2014 (SOL2014-03-29T17:48) by the Interface Region Imaging Spectrograph (IRIS). IRIS detected large intensity enhancements of the Mg II h and k lines, subordina…
The Properties of Solar Energetic Particle Event-Associated Coronal Mass Ejections Reported in Different CME Catalogs
Cane, H. V.; Richardson, I. G.; von Rosenvinge, T. T.
We compare estimates of the speed and width of coronal mass ejections (CMEs) in several catalogs for the CMEs associated with ∼ 200 solar energetic particle (SEP) events in 2006 - 2013 that included 25 MeV protons. The catalogs used are: CDAW, CACTUS, SEEDS, and CORIMP, all derived from observations by the LASCO coronagraphs on the SOHO spacecraft…
Quantifying the Difference Between the Flux-Tube Expansion Factor at the Source Surface and at the Alfvén Surface Using a Global MHD Model for the Solar Wind
Cohen, O.
The potential-field approximation has been providing a fast and computationally inexpensive estimation for the solar corona's global magnetic-field geometry for several decades. In contrast, more physics-based global magnetohydrodynamic (MHD) models have been used for a similar purpose, while being much more computationally expensive. Here, we inv…
Coronal Pseudo-Streamer and Bipolar Streamer Observed by SOHO/UVCS in March 2008
Riley, P.; Abbo, L.; Wang, Y. -M. +1 more
The past solar minimum is characterized by several peculiar aspects and by a complex magnetic topology with two different types of coronal streamers: pseudo-streamers and bipolar streamers. Pseudo-streamers or unipolar streamer are coronal structures that separate coronal holes of the same polarity, without a current sheet in the outer corona; unl…
Coronal Sources and In Situ Properties of the Solar Winds Sampled by ACE During 1999 - 2008
Li, Xing; Fu, Hui; Li, Bo +4 more
We identify the coronal sources of the solar winds sampled by the ACE spacecraft during 1999 - 2008 and examine the in situ solar wind properties as a function of wind sources. The standard two-step mapping technique is adopted to establish the photospheric footpoints of the magnetic flux tubes along which the ACE winds flow. The footpoints are th…
Evidence of Twisted Flux-Tube Emergence in Active Regions
Mandrini, C. H.; Démoulin, P.; López Fuentes, M. +1 more
Elongated magnetic polarities are observed during the emergence phase of bipolar active regions (ARs). These extended features, called magnetic tongues, are interpreted as a consequence of the azimuthal component of the magnetic flux in the toroidal flux-tubes that form ARs. We develop a new systematic and user-independent method to identify AR to…