Search Publications
Interplanetary acceleration of coronal mass ejections
St. Cyr, O. C.; Kaiser, M. L.; Gopalswamy, N. +3 more
Using an observed relation between speeds of CMEs near the Sun and in the solar wind, we determine an “effective” acceleration acting on the CMEs. We found a linear relation between this effective acceleration and the initial speed of the CMEs. The acceleration is similar to that of the slow solar wind in magnitude. The average solar wind speed na…
Properties of coronal mass ejections: SOHO LASCO observations from January 1996 to June 1998
St. Cyr, O. C.; Plunkett, S. P.; Michels, D. J. +9 more
We report the properties of all the 841 coronal mass ejections (CMEs) observed by the Solar and Heliospheric Observatory (SOHO) Large Angle Spectroscopic Coronagraph (LASCO) C2 and C3 white-light coronagraphs from January 1996 through June 1998, and we compare those properties to previous observations by other similar instruments. Both the CME rat…
Coronal Mass Ejections and Forbush Decreases
Cane, Hilary V.
Coronal Mass Ejections (CMEs) are plasma eruptions from the solar atmosphere involving previously closed field regions which are expelled into the interplanetary medium. Such regions, and the shocks which they may generate, have pronounced effects on cosmic ray densities both locally and at some distance away. These energetic particle effects can …
Dynamic Variations at the Base of the Solar Convection Zone
Thompson, M. J.; Howe, R.; Hill, F. +5 more
We have detected changes in the rotation of the sun near the base of its convective envelope, including a prominent variation with a period of 1.3 years at low latitudes. Such helioseismic probing of the deep solar interior has been enabled by nearly continuous observation of its oscillation modes with two complementary experiments. Inversion of t…
The SOLAR2000 empirical solar irradiance model and forecast tool
Floyd, L.; Viereck, R.; Woods, T. +5 more
SOLAR2000 is a collaborative project for accurately characterizing solar irradiance variability across the spectrum. A new image- and full-disk proxy empirical solar irradiance model, SOLAR2000, is being developed that is valid in the spectral range of 1-1,000,000 nm for historical modeling and forecasting throughout the solar system. The overarch…
Relationship of halo coronal mass ejections, magnetic clouds, and magnetic storms
Thompson, B. J.; Webb, D. F.; Crooker, N. U. +2 more
Halo coronal mass ejections (CMEs) had been rarely reported in coronagraph observations of the Sun before the Solar and Heliospheric Observatory (SOHO) mission. Since mid-1996, however, the SOHO Large Angle Spectrometric Coronagraph (LASCO) instruments have observed many halo or partial-halo CMEs. A halo CME, especially when associated with solar …
Cosmic protons
Usoskin, I.; Laitinen, T.; Valtonen, E. +200 more
The primary proton spectrum in the kinetic energy range 0.2 to 200 GeV was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at an altitude of 380 km. The complete data set combining three shuttle attitudes and including all known systematic effects is presented.
Large-Angle Spectrometric Coronagraph Measurements of the Energetics of Coronal Mass Ejections
Howard, R. A.; Dere, K. P.; Vourlidas, A. +1 more
We examine the energetics of coronal mass ejections (CMEs) with data from the large-angle spectrometric coronagraphs (LASCO) on SOHO. The LASCO observations provide fairly direct measurements of the mass, velocity, and dimensions of CMEs. Using these basic measurements, we determine the potential and kinetic energies and their evolution for severa…
Time-Distance Inversion Methods and Results - (Invited Review)
Kosovichev, A. G.; Scherrer, P. H.; Duvall, T. L. _Jr., Jr.
The current interpretations of the travel-time measurements in quiet and active regions on the Sun are discussed. These interpretations are based on various approximations to the 3-D wave equation such as the Fermat principle for acoustic rays and the Born approximation. The ray approximation and its modifications have provided the first view of t…
Leptons in near earth orbit
Usoskin, I.; Laitinen, T.; Valtonen, E. +199 more
The lepton spectra in the kinetic energy ranges 0.2 to 40 GeV for e- and 0.2 to 3 GeV for e+ were measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at altitudes near 380km. >From the origin of the leptons two distinct spectra were observed: a higher energy spectrum and a substantial secon…