Search Publications
Intensity contrast of solar network and faculae
Solanki, S. K.; Yeo, K. L.; Krivova, N. A.
Aims: This study aims at setting observational constraints on the continuum and line core intensity contrast of network and faculae, specifically, their relationship with magnetic field and disc position.
Methods: Full-disc magnetograms and intensity images by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observat…
High-rigidity Forbush decreases: due to CMEs or shocks?
Antia, H. M.; Subramanian, P.; Hayashi, Y. +7 more
Aims: We seek to identify the primary agents causing Forbush decreases (FDs) in high-rigidity cosmic rays observed from the Earth. In particular, we ask if these FDs are caused mainly by coronal mass ejections (CMEs) from the Sun that are directed towards the Earth, or by their associated shocks.
Methods: We used the muon data at cutoff …
Improved methods for determining the kinematics of coronal mass ejections and coronal waves
Long, D. M.; Bloomfield, D. S.; Habbal, S. R. +5 more
Context. The study of solar eruptive events and associated phenomena is of great importance in the context of solar and heliophysics. Coronal mass ejections (CMEs) and coronal waves are energetic manifestations of the restructuring of the solar magnetic field and mass motion of the plasma. Characterising this motion is vital for deriving the dynam…
Improving the performance of solar flare prediction using active longitudes information
Huang, X.; Zhang, L.; Wang, H. +1 more
Context. Solar flare prediction models normally depend on properties of active regions, such as sunspot area, McIntosh classifications, Mount Wilson classifications, and various measures of the magnetic field. Nevertheless, the positional information of active regions has not been used.
Aims: We define a metric, DARAL (distance bet…
Correlation of spectral solar irradiance with solar activity as measured by VIRGO
Schmutz, W.; Shapiro, A. I.; Wehrli, C.
Context. The variability of solar spectral irradiance (SSI) over the rotational period and its trend over the solar activity cycle are important for understanding the Sun-Earth connection as well as for observational constraints for solar models. Recently the Spectral Irradiance Monitor (SIM) experiment on the Solar Radiation and Climate Experimen…
Comparison of geoeffectiveness of coronal mass ejections and corotating interaction regions
Vršnak, B.; Verbanac, G.; Bandić, M. +2 more
Context. A detailed comparison of the geomagnetic responses to interplanetary coronal mass ejection (ICMEs) and corotating interaction regions (CIRs) during solar cycle 23 was performed using geomagnetic indices Dst, Ap, and AE.
Aims: We aim to find out if there are relative differences in the response of various magnetospheric current system…
Radial profile of the inner heliospheric magnetic field as deduced from Faraday rotation observations
Mancuso, S.; Garzelli, M. V.
Faraday rotation measures (RMs) of the polarized emission from extragalactic radio sources occulted by the coronal plasma were used to infer the radial profile of the inner heliospheric magnetic field near the solar minimum. By inverting LASCO/SOHO polarized brightness (pB) data taken during the observations in May 1997, we retrieved the electron …
Origin of wide-band IP type II bursts
Valtonen, E.; Allawi, H.; Pohjolainen, S.
Context. Different types of interplanetary (IP) type II bursts have been observed, where the more usual ones show narrow-band and patchy emissions, sometimes with harmonics, and which at intervals may disappear completely from the dynamic spectrum. The more unusual bursts are wide-band and diffuse, show no patches or breaks or harmonic emission, a…
Coronal magnetic field strength from Type II radio emission: complementarity with Faraday rotation measurements
Mancuso, S.; Garzelli, M. V.
We analyzed the band splitting of a Type II radio burst observed on 1997 May 12 by ground- and space-based radio spectrometers. Type II radio emission is the most evident signature of coronal shock waves and the observed band splitting is generally interpreted as due to plasma emission from both upstream and downstream shock regions. From the infe…
Temperature dependence of ultraviolet line parameters in network and internetwork regions of the quiet Sun and coronal holes
Peter, H.; Curdt, W.; Wang, X. +3 more
Aims: We study the temperature dependence of the average Doppler shift and the non-thermal line width in network and internetwork regions for both the quiet Sun (QS) and the coronal hole (CH), by using observations of the Solar Ultraviolet Measurements of Emitted Radiation instrument onboard the Solar and Heliospheric Observatory spacecraft. …