Search Publications
Observations of an extreme storm in interplanetary space caused by successive coronal mass ejections
Kajdič, Primož; Lavraud, Benoit; Nitta, Nariaki V. +8 more
Space weather refers to dynamic conditions on the Sun and in the space environment of the Earth, which are often driven by solar eruptions and their subsequent interplanetary disturbances. It has been unclear how an extreme space weather storm forms and how severe it can be. Here we report and investigate an extreme event with multi-point remote-s…
> 25 MeV Proton Events Observed by the High Energy Telescopes on the STEREO A and B Spacecraft and/or at Earth During the First ∼ Seven Years of the STEREO Mission
Christian, E. R.; Leske, R. A.; Labrador, A. W. +7 more
Using observations from the High Energy Telescopes (HETs) on the STEREO A and B spacecraft and similar observations from near-Earth spacecraft, we summarize the properties of more than 200 individual > 25 MeV solar proton events, some detected by multiple spacecraft, that occurred from the beginning of the STEREO mission in October 2006 to Dece…
Multi-Scale Gaussian Normalization for Solar Image Processing
Morgan, Huw; Druckmüller, Miloslav
Extreme ultra-violet images of the corona contain information over a wide range of spatial scales, and different structures such as active regions, quiet Sun, and filament channels contain information at very different brightness regimes. Processing of these images is important to reveal information, often hidden within the data, without introduci…
Connecting Speeds, Directions and Arrival Times of 22 Coronal Mass Ejections from the Sun to 1 AU
Luhmann, J. G.; Möstl, C.; Farrugia, C. J. +15 more
Forecasting the in situ properties of coronal mass ejections (CMEs) from remote images is expected to strongly enhance predictions of space weather and is of general interest for studying the interaction of CMEs with planetary environments. We study the feasibility of using a single heliospheric imager (HI) instrument, imaging the solar wind densi…
The magnetic field in the solar atmosphere
Solanki, Sami K.; Wiegelmann, Thomas; Thalmann, Julia K.
This publication provides an overview of magnetic fields in the solar atmosphere with the focus lying on the corona. The solar magnetic field couples the solar interior with the visible surface of the Sun and with its atmosphere. It is also responsible for all solar activity in its numerous manifestations. Thus, dynamic phenomena such as coronal m…
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…
Anomalous expansion of coronal mass ejections during solar cycle 24 and its space weather implications
Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji +3 more
The familiar correlation between the speed and angular width of coronal mass ejections (CMEs) is also found in solar cycle 24, but the regression line has a larger slope: for a given CME speed, cycle 24 CMEs are significantly wider than those in cycle 23. The slope change indicates a significant change in the physical state of the heliosphere, due…
A Multi-Observatory Inter-Comparison of Line-of-Sight Synoptic Solar Magnetograms
Liu, Y.; Riley, P.; Hoeksema, T. +7 more
The observed photospheric magnetic field is a crucial parameter for understanding a range of fundamental solar and heliospheric phenomena. Synoptic maps, in particular, which are derived from the observed line-of-sight photospheric magnetic field and built up over a period of 27 days, are the main driver for global numerical models of the solar co…
Predicting the Sun's Polar Magnetic Fields with a Surface Flux Transport Model
Hathaway, David H.; Upton, Lisa
The Sun's polar magnetic fields are directly related to solar cycle variability. The strength of the polar fields at the start (minimum) of a cycle determine the subsequent amplitude of that cycle. In addition, the polar field reversals at cycle maximum alter the propagation of galactic cosmic rays throughout the heliosphere in fundamental ways. W…
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…