Search Publications
Reconstruction of total and spectral solar irradiance from 1974 to 2013 based on KPVT, SoHO/MDI, and SDO/HMI observations
Solanki, S. K.; Glassmeier, K. H.; Yeo, K. L. +1 more
Context. Total and spectral solar irradiance are key parameters in the assessment of solar influence on changes in the Earth's climate.
Aims: We present a reconstruction of daily solar irradiance obtained using the SATIRE-S model spanning 1974 to 2013 based on full-disc observations from the KPVT, SoHO/MDI, and SDO/HMI.
Methods: SATIRE-S…
Statistical survey of widely spread out solar electron events observed with STEREO and ACE with special attention to anisotropies
Gómez-Herrero, R.; Malandraki, O.; Dresing, N. +4 more
Context. In February 2011, the two STEREO spacecrafts reached a separation of 180 degrees in longitude, offering a complete view of the Sun for the first time ever. When the full Sun surface is visible, source active regions of solar energetic particle (SEP) events can be identified unambiguously. STEREO, in combination with near-Earth observatori…
The formation heights of coronal shocks from 2D density and Alfvén speed maps
Gallagher, Peter T.; Zucca, Pietro; Carley, Eoin P. +1 more
Context. Super-Alfvénic shocks associated with coronal mass ejections (CMEs) can produce radio emission known as Type II bursts. In the absence of direct imaging, accurate estimates of coronal electron densities, magnetic field strengths, and Alfvén speeds are required to calculate the kinematics of shocks. To date, 1D radial models have been used…
LOFAR tied-array imaging of Type III solar radio bursts
Magdalenić, J.; McKean, J. P.; Eislöffel, J. +82 more
Context. The Sun is an active source of radio emission which is often associated with energetic phenomena such as solar flares and coronal mass ejections (CMEs). At low radio frequencies (<100 MHz), the Sun has not been imaged extensively because of the instrumental limitations of previous radio telescopes.
Aims: Here, the combined high sp…
Long-period intensity pulsations in the solar corona during activity cycle 23
Auchère, F.; Bocchialini, K.; Solomon, J. +1 more
We report on the detection (10σ) of 917 events of long-period (3 to 16 h) intensity pulsations in the 19.5 nm passband of the SOHO Extreme ultraviolet Imaging Telescope. The data set spans from January 1997 to July 2010, i.e. the entire solar cycle 23 and the beginning of cycle 24. The events can last for up to six days and have relative amplitude…
Magnetic field and radiative transfer modelling of a quiescent prominence
Heinzel, P.; Schmieder, B.; Gunár, S. +3 more
Aims: The aim of this work is to analyse the multi-instrument observations of the June 22, 2010 prominence to study its structure in detail, including the prominence-corona transition region and the dark bubble located below the prominence body.
Methods: We combined results of the 3D magnetic field modelling with 2D prominence fine struc…
The radial gradient of the near-surface shear layer of the Sun
Schou, J.; Gizon, L.; Barekat, A.
Context. Helioseismology has provided unprecedented information about the internal rotation of the Sun. One of the important achievements was the discovery of two radial shear layers: one near the bottom of the convection zone (the tachocline) and one near the surface. These shear layers may be important ingredients for explaining the magnetic cyc…
The low-high-low trend of type III radio burst starting frequencies and solar flare hard X-rays
Kontar, Eduard P.; Vilmer, Nicole; Reid, Hamish A. S.
Aims: Using simultaneous X-ray and radio observations from solar flares, we investigate the link between the type III radio burst starting frequency and hard X-ray spectral index. For a proportion of events the relation derived between the starting height (frequency) of type III radio bursts and the electron beam velocity spectral index (dedu…
Modelling total solar irradiance since 1878 from simulated magnetograms
Solanki, S. K.; Krivova, N. A.; Jiang, J. +1 more
Aims: We present a new model of total solar irradiance (TSI) based on magnetograms simulated with a surface flux transport model (SFTM) and the Spectral And Total Irradiance REconstructions (SATIRE) model. Our model provides daily maps of the distribution of the photospheric field and the TSI starting from 1878.
Methods: The modelling is…
The chromosphere above sunspots at millimeter wavelengths
Solanki, S. K.; White, S. M.; Loukitcheva, M.
Aims: The aim of this paper is to demonstrate that millimeter wave data can be used to distinguish between various atmospheric models of sunspots, whose temperature structure in the upper photosphere and chromosphere has been the source of some controversy.
Methods: We use observations of the temperature contrast (relative to the quiet S…