Search Publications
Reducing heliospheric magnetic flux from coronal mass ejections without disconnection
Crooker, N. U.; Gosling, J. T.; Kahler, S. W.
Until 1995, disconnection at the Sun was thought to be the only solution to the problem of balancing the magnetic flux coronal mass ejections (CMEs) added to the heliosphere, in spite of the fact that the expected solar wind signature of disconnection was rare. Disconnection was pictured as merging between open field lines to create completely dis…
Determination of geometrical and kinematical properties of halo coronal mass ejections using the cone model
Plunkett, S. P.; Zhao, X. P.; Liu, W.
Many broadside coronal mass ejections (CMEs) propagate almost radially beyond the first couple of solar radii, and their angular widths remain nearly constant while propagating through the corona. Assuming that these characteristics hold true for halo CMEs that originate far from solar limbs, some useful geometric and kinematic properties of halo …
Successive CMEs and complex ejecta
St. Cyr, O. C.; Plunkett, S. P.; Burlaga, L. F.
We identified three sets of successive halo CMEs directed toward Earth (two or more CMEs observed within 1-4 days in the corona) and the corresponding flows and magnetic fields at 1 AU. Each set of successive halo CMEs was associated with complex ejecta at 1 AU. Complex ejecta were defined by [2001] as fast (>600 km/s) flows that are neither co…
A statistical study on the geoeffectiveness of Earth-directed coronal mass ejections from March 1997 to December 2000
Wang, S.; Wang, J. X.; Wang, Y. M. +2 more
We have identified 132 Earth-directed coronal mass ejections (CMEs) based on the observations of the Large Angle Spectroscopic Coronagraph (LASCO) and Extreme Ultraviolet Imaging Telescope (EIT) on board of Solar and Heliospheric Observatory (SOHO) from March 1997 to December 2000 and carried out a statistical study on their geoeffectiveness. The …
Solar flares, type III radio bursts, coronal mass ejections, and energetic particles
Cane, H. V.; Erickson, W. C.; Prestage, N. P.
In this correlative study between >20 MeV solar proton events, coronal mass ejections (CMEs), flares, and radio bursts it is found that essentially all of the proton events are preceded by groups of type III bursts and all are preceded by CMEs. These type III bursts (that are a flare phenomenon) usually are long-lasting, intense bursts seen in …
Variability of magnetospheric storms driven by different solar wind perturbations
Koskinen, Hannu E. J.; Schwenn, Rainer; Huttunen, K. Emilia J.
We have investigated the solar wind drivers of magnetic storms during the rising phase of solar cycle 23 from January 1996 to December 1999. We used observations of coronal mass ejections (CMEs) by the Large Angle and Spectrometric Coronagraph instrument on SOHO and in situ solar wind observations by Wind, IMP 8, and ACE spacecraft. The storms wer…
Merging of coronal and heliospheric numerical two-dimensional MHD models
Luhmann, J. G.; Odstrcil, D.; Riley, P. +4 more
Space weather research requires investigation of a complex chain of coupled dynamic phenomena occurring simultaneously on various spatial and temporal scales between the Sun and Earth. Specialized physically based numerical models have been developed to address particular aspects of the entire system. However, an integrated modeling approach is ne…
April 2000 magnetic storm: Solar wind driver and magnetospheric response
Pulkkinen, Tuija I.; Palmroth, Minna; Pulkkinen, Antti +4 more
On 4 April 2000, a coronal mass ejection (CME) took place close to the western limb of the Sun. The shock front of the CME hit the Earth's magnetosphere on 6 April. A strong interplanetary southward BZ event in the sheath region caused a magnetic storm that was the second strongest in the year 2000 if quantified by the peak of the Dst i…
Polarity reversal of the solar magnetic field during cycle 23
Andrews, M. D.; Sheeley, N. R.; Wang, Y. -M.
Using magnetograph data, coronagraph observations, and source surface extrapolations, we examine the evolution of the photospheric magnetic field from 1996 through the 2000-2001 polarity reversal and show how this evolution is reflected in coronal holes, coronal streamers, the heliospheric current sheet (HCS), and the solar wind. The photospheric …
Solar mean magnetic field variability: A wavelet approach to Wilcox Solar Observatory and SOHO/Michelson Doppler Imager observations
Liu, Wei; Hoeksema, J. Todd; Scherrer, Philip H. +2 more
Solar mean magnetic field (SMMF) measurements from the Wilcox Solar Observatory and with the SOHO/MDI instrument are described and analyzed. Even though two completely different methods of observation are used, the two data sets obtained show a strong similarity. Using continuous wavelet transforms, SMMF variability is found at a number of tempora…