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A new model of solar EUV irradiance variability 2. Comparisons with empirical models and observations and implications for space weather
Mariska, J. T.; Warren, H. P.; Bishop, J. +1 more
Motivated by the need for reliable specification of the Sun's electromagnetic radiation in the extreme ultraviolet (EUV) spectrum, we have developed a new model of solar EUV irradiance variability at wavelengths from 50 to 1200 Å. Solar images are used to quantify changes in the sources of EUV irradiance during the solar cycle. Optically thin EUV …
Cassini between Venus and Earth: Detection of interstellar dust
Dikarev, V.; Kempf, S.; Krüger, H. +5 more
We report the successful in situ measurement of interstellar dust particles inside the orbit of the Earth with the Cosmic Dust Analyzer (CDA) on the Cassini spacecraft. The impact ionization subsystem of the CDA is similar to the instruments on Ulysses and Galileo. As the heliocentric velocity and the direction of the interstellar dust flux are we…
Observations of the Sun's magnetic field during the recent solar maximum
Hoeksema, J. T.; Appourchaux, T.; Sanderson, T. R. +1 more
We present new observations and analyses of the Sun's magnetic field and coronal holes. Using magnetic field observations from the Wilcox Solar Observatory, we present a simple means whereby the tilt angle of the current sheet can be calculated. We use a data set covering the last 26 years, which shows for the first time how the dipole component r…
Buoyant disruption of magnetic arcades with self-induced shearing
Manchester, Ward
We present the results of magnetohydrodynamic (MHD) simulations of the nonlinear development of instabilities of magnetically sheared arcades and show how they relate to plasmoid ejections and coronal mass ejections (CMEs). To model the arcade disruptions, we capitalize on a family of analytical solutions for initial states; these describe magneti…
Penetration of the heliosphere by the interstellar dust stream during solar maximum
Krüger, H.; Grün, E.; Altobelli, N. +1 more
We analyze the Ulysses in situ measurements of interstellar dust in the solar system with respect to the temporal variation of the flux density. The data set that is used covers the time from after Ulysses' fly-by of Jupiter up to the most recent data taken end of November 2002. The decrease in interstellar dust flux observed in 1996 can be explai…
On the source and acceleration of energetic He+: A long-term observation with ACE/SEPICA
Farrugia, C. J.; Galvin, A. B.; Klecker, B. +6 more
We report on a systematic study of the He+/He2+ abundance ratio in the energetic population during the years 1998-2000. For the investigation we have used data in the energy range 0.25-0.8 MeV/n from SEPICA on board ACE and from CELIAS STOF on SOHO in the energy range 0.085-0.28 MeV/q. The ratio is quite variable, with values…
MHD tomography using interplanetary scintillation measurement
Hayashi, Keiji; Kojima, Masayoshi; Tokumaru, Munetoshi +1 more
The MHD tomography analysis, an advanced version of the computer-assisted tomography (CAT) analysis for interplanetary scintillation (IPS) observational data, is presented. When combined with a MHD simulation, the CAT analysis can reconstruct the MHD-based three-dimensional solar wind structure within 1 AU from the IPS line-of-sight integrated vel…
A statistical comparison of interplanetary shock and CME propagation models
Cho, K. -S.; Moon, Y. -J.; Dryer, M. +3 more
We have compared the prediction capability of two types of Sun-Earth connection models: (1) ensemble of physics-based shock propagation models (STOA, STOA-2, ISPM, and HAFv.2) and (2) empirical CME propagation (CME-ICME and CME-IP shock) models. For this purpose, we have selected 38 near-simultaneous pairs of coronal mass ejections (CMEs) and metr…
Energetic particle propagation in the inner heliosphere as deduced from low-frequency (<100 kHz) observations of type III radio bursts
Cane, H. V.; Erickson, W. C.
Solar energetic particle (SEP) events are well-associated with solar flares. It is observed that the delay between the time of the flare and the first-arriving particles at a spacecraft increases with increasing difference between the flare longitude and the foot point of the field line on which the spacecraft is located. This difference we call t…
Spectral observations of transient features in the FUV Jovian polar aurora
Clarke, J. T.; Grodent, D.; Gustin, J. +2 more
Images of the Jovian FUV aurora show several morphologically and dynamically different regions. The main oval is usually fairly steady while the high-latitude emission inside the oval can vary over timescales of <1 min. We describe time and spatially resolved spectral observations of the Jovian aurora made with the Space Telescope Imaging Spect…