Search Publications
Irradiance models
Solanki, S. K.; Krivova, N. A.; Wenzler, T.
Measurements of solar irradiance have revealed variations at all the sampled time scales (ranging from minutes to the length of the solar cycle). One important task of models is to identify the causes of the observed (total and spectral) irradiance variations. Another major aim is to reconstruct irradiance over time scales longer than sampled by d…
Variation of the full Sun hydrogen Lyman profiles through solar cycle 23
Vial, J. -C.; Wilhelm, K.; Curdt, W. +3 more
The hydrogen Lyman (Lyα, 121.267 nm and Lyβ, 102.572 nm) lines are important contributors to the solar extreme ultra violet (EUV) flux which illuminates the upper Earth’s atmosphere. From high resolution spectral observations performed with the solar ultraviolet measurement of emitted radiations (SUMER) spectrometer on the Solar and Heliospheric O…
Energetic particle signatures of geoeffective coronal mass ejections
Laitinen, T.; Valtonen, E.; Huttunen-Heikinmaa, K.
We have studied statistically associations of moderate and intense geomagnetic storms with coronal mass ejections (CMEs) and energetic particle events. The goal was to identify specific energetic particle signatures, which could be used to improve the predictions of the geoeffectiveness of full and partial halo CMEs. Protons in the range 1-110 MeV…
Centre-to-limb variation of photospheric facular radiance and image resolution
Domingo, Vicente; Ortiz, Ada; Sanahuja, Blai +1 more
We study the effect of the angular resolution on the determination of the angular properties of the facular radiance. We analyze photospheric intensity in the continuum, around the Ni 676.8 nm line, and longitudinal magnetic field along the line of sight, measured by the MDI instrument aboard SOHO with two spatial resolutions, 4″ and 1.2″ (2″ and …
Solar cycle evolution of the contrast of small photospheric magnetic elements
Ortiz, Ada
Solar irradiance variations produced on the solar rotation time-scale are known to be driven by the passage of active regions while, during the last years, the origin of variations on the solar cycle time-scale has been under debate. Nowadays, there is an agreement that the magnetic network has an important contribution to these long-term variatio…
Model of the all-sky He II 30.4 nm solar flux
Auchère, F.; von Steiger, R.; Witte, M. +3 more
Because of the orbit characteristics of the vast majority of spacecraft, the solar flux has been generally measured at Earth or in the plane of the ecliptic. So far, most published studies did not consider the fact that the extreme ultraviolet (EUV) solar flux is largely anisotropic. Indeed, in the EUV, the distribution of very contrasted bright a…
Temporal profiles of solar energetic particle events from SOHO/EPHIN data
Kunow, H.; Muller-Mellin, R.; Gómez-Herrero, R. +3 more
Temporal profiles of energetic ions and electrons observed at 1 AU during solar energetic particle events are mainly determined by particle injection features, the observer location relative to the source region at the Sun, and the interplanetary space plasma and field conditions during particle transport. In this work, temporal profiles of 18 sol…