Search Publications
Determining the Intrinsic CME Flux Rope Type Using Remote-sensing Solar Disk Observations
Palmerio, E.; Kilpua, E. K. J.; Green, L. M. +4 more
A key aim in space weather research is to be able to use remote-sensing observations of the solar atmosphere to extend the lead time of predicting the geoeffectiveness of a coronal mass ejection (CME). In order to achieve this, the magnetic structure of the CME as it leaves the Sun must be known. In this article we address this issue by developing…
Comprehensive Analysis of the Geoeffective Solar Event of 21 June 2015: Effects on the Magnetosphere, Plasmasphere, and Ionosphere Systems
Fineschi, Silvano; Stangalini, Marco; Bruno, Roberto +34 more
A full-halo coronal mass ejection (CME) left the Sun on 21 June 2015 from active region (AR) NOAA 12371. It encountered Earth on 22 June 2015 and generated a strong geomagnetic storm whose minimum Dst value was −204 nT. The CME was associated with an M2-class flare observed at 01:42 UT, located near disk center (N12 E16). Using satellite data from…
On-Disc Observations of Flux Rope Formation Prior to Its Eruption
Palmerio, E.; van Driel-Gesztelyi, L.; Kilpua, E. K. J. +6 more
Coronal mass ejections (CMEs) are one of the primary manifestations of solar activity and can drive severe space weather effects. Therefore, it is vital to work towards being able to predict their occurrence. However, many aspects of CME formation and eruption remain unclear, including whether magnetic flux ropes are present before the onset of er…
Observations and Modelling of the Pre-flare Period of the 29 March 2014 X1 Flare
Long, D. M.; Harra, L. K.; Matthews, S. A. +3 more
On 29 March 2014, NOAA Active Region (AR) 12017 produced an X1 flare that was simultaneously observed by an unprecedented number of observatories. We have investigated the pre-flare period of this flare from 14:00 UT until 19:00 UT using joint observations made by the Interface Region Imaging Spectrometer (IRIS) and the Hinode Extreme Ultraviolet …
Characterizing Solar Energetic Particle Event Profiles with Two-Parameter Fits
Kahler, Stephen W.; Ling, Alan G.
The intensity-time profiles of solar energetic (E >10 MeV) particle (SEP) events observed at 1 AU reflect a number of physical processes involving solar injection and interplanetary transport. In addition to energy spectral and composition studies, SEP intensity-time profiles are the basis for diagnostic timescales needed for describing and mod…
Review of Image Quality Measures for Solar Imaging
Popowicz, Adam; Bernacki, Krzysztof; Orlov, Valeri +1 more
Observations of the solar photosphere from the ground encounter significant problems caused by Earth's turbulent atmosphere. Before image reconstruction techniques can be applied, the frames obtained in the most favorable atmospheric conditions (the so-called lucky frames) have to be carefully selected. However, estimating the quality of images co…
Apparent and Intrinsic Evolution of Active Region Upflows
Janvier, Miho; Baker, Deborah; Démoulin, Pascal +1 more
We analyze the evolution of Fe XII coronal plasma upflows from the edges of ten active regions (ARs) as they cross the solar disk using the Hinode Extreme Ultraviolet Imaging Spectrometer (EIS) to do this. Confirming the results of Démoulin et al. (Sol. Phys.283, 341, 2013), we find that for each AR there is an observed long-term evolution of the …
High-Resolution Vector Magnetograms of the Sun's Poles from Hinode: Flux Distributions and Global Coronal Modeling
Petrie, Gordon
The Sun's polar fields play a leading role in structuring the large-scale solar atmosphere and in determining the interplanetary magnetic field. They are also believed to supply the seed field for the subsequent solar activity cycle. However, present-day synoptic observations do not have sufficient spatial resolution or sensitivity to diagnose acc…
SPIN: An Inversion Code for the Photospheric Spectral Line
Mathew, Shibu K.; Yadav, Rahul; Tiwary, Alok Ranjan
Inversion codes are the most useful tools to infer the physical properties of the solar atmosphere from the interpretation of Stokes profiles. In this paper, we present the details of a new Stokes Profile INversion code (SPIN) developed specifically to invert the spectro-polarimetric data of the Multi-Application Solar Telescope (MAST) at Udaipur …
Oscillations in the 45 - 5000 MHz Radio Spectrum of the 18 April 2014 Flare
Monstein, Christian; Rybák, Ján; Karlický, Marian
Using a new type of oscillation map, made from the radio spectra by the wavelet technique, we study the 18 April 2014 M7.3 flare (SOL2014-04-18T13:03:00L245C017). We find a quasi-periodic character of this flare with periods in the range 65 - 115 seconds. At the very beginning of this flare, in connection with the drifting pulsation structure (pla…