Search Publications
The correlation between solar energetic particle peak intensities and speeds of coronal mass ejections: Effects of ambient particle intensities and energy spectra
Kahler, S. W.
The correlation of peak intensities of solar energetic particle (SEP) events with the speeds of the associated coronal mass ejections (CMEs) is understood to be a result of SEP acceleration at shocks driven by the CMEs. However, the peak SEP intensities associated with CMEs of a given speed vary over ~ 4 orders of magnitude. We examine a database …
Three-dimensional numerical simulation of MHD waves observed by the Extreme Ultraviolet Imaging Telescope
Plunkett, S. P.; Thompson, B. J.; Wu, S. T. +4 more
We investigate the global large amplitude waves propagating across the solar disk as observed by the SOHO/Extreme Ultraviolet Imaging Telescope (EIT). These waves appear to be similar to those observed in Hα in the chromosphere and which are known as ``Moreton waves,'' associated with large solar flares [Moreton, 1960, 1964]. Uchida [19…
Near-Sun and near-Earth manifestations of solar eruptions
Kaiser, M. L.; Gopalswamy, N.; Bougeret, J. -L. +1 more
We compare the near-Sun and near-Earth manifestations of solar eruptions that occurred during November 1994 to June 1998. We compared white-light coronal mass ejections, metric type II radio bursts, and extreme ultraviolet wave transients (near the Sun) with interplanetary (IP) signatures such as decameter-hectometric type II bursts, kilometric ty…
Fast ejecta during the ascending phase of solar cycle 23: ACE observations, 1998-1999
Webb, D. F.; Burlaga, L. F.; Zurbuchen, T. H. +3 more
We discuss fast ejecta observed at 1 AU during a period of increasing solar activity from February 5, 1998, to November 29, 1999. ``Fast ejecta'' are transient, noncorotating flows that move past the Earth during a day or more, with a maximum speed >600 km s-1. We identify two classes of fast ejecta at 1 AU: (1) magnetic clouds, whos…
Improvements to the HAF solar wind model for space weather predictions
Dryer, M.; Smith, Z.; Fry, C. D. +5 more
We have assembled and tested, in real time, a space weather modeling system that starts at the Sun and extends to the Earth through a set of coupled, modular components. We describe recent efforts to improve the Hakamada-Akasofu-Fry (HAF) solar wind model that is presently used in our geomagnetic storm prediction system. We also present some resul…
Ion cyclotron diffusion of velocity distributions in the extended solar corona
Cranmer, Steven R.
The Ultraviolet Coronagraph Spectrometer aboard the Solar and Heliospheric Observatory has revealed strong kinetic anisotropies and extremely large perpendicular temperatures of heavy ions in the extended solar corona. These observations have revived interest in the idea that the high-speed solar wind is heated and accelerated by the dissipation o…
Eruption and acceleration of flare-associated coronal mass ejection loops in the low corona
Plunkett, S. P.; Thompson, B. J.; Gurman, J. B. +1 more
Observations made by the EUV imaging telescope (EIT) and the Large-Angle Spectrometric Coronagraph (LASCO) on board the Solar Heliospheric Observatory (SOHO) have been used to characterize the eruption and acceleration of flare-associated coronal mass ejections (CMEs) in the low corona. For three well-observed limb events we tracked CME loops back…
A new model of solar EUV irradiance variability: 1. Model formulation
Mariska, J. T.; Warren, H. P.; Lean, J.
We present a new model of solar irradiance variability at extreme ultraviolet wavelengths (EUV, 50-1200 Å). In this model, quiet Sun, coronal hole, and active region intensities for optically thin emission lines are computed from emission measure distributions determined from spectrally and spatially resolved observations. For optically thick emis…
Validating the solar EUV proxy, E10.7
Tobiska, W. Kent
A demonstration of the improvement in thermospheric densities using the daily E10.7 proxy compared to F10.7 is shown. The daily altitude decay for the Solar Mesosphere Explorer (SME) satellite from April 1, 1982 through August 9, 1983, using both proxies and the actual altitude data, are compared. The F10.7 case fi…
Electromagnetic heavy ion cyclotron instability: Anisotropy constraint in the solar corona
Gary, S. Peter; Ofman, Leon; Winske, Dan +1 more
The electromagnetic proton cyclotron anisotropy instability is driven by T⊥p/T∥p>1 where p represents protons and the directional subscripts denote directions relative to the background magnetic field. Fluctuating field growth leads to wave-particle scattering, which in turn imposes an upper bound on the anisotropy of the …