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Connecting Coronal Mass Ejections to Their Solar Active Region Sources: Combining Results from the HELCATS and FLARECAST Projects  

Sophie A. Murray   Submitted: 2018-03-27 05:46

Coronal mass ejections (CMEs) and other solar eruptive phenomena can be physically linked by combining data from a multitude of ground-based and space-based instruments alongside models, however this can be challenging for automated operational systems. The EU Framework Package 7 HELCATS project provides catalogues of CME observations and properties from the Heliospheric Imagers onboard the two NASA/STEREO spacecraft in order to track the evolution of CMEs in the inner heliosphere. From the main HICAT catalogue of over 2,000 CME detections, an automated algorithm has been developed to connect the CMEs observed by STEREO to any corresponding solar flares and active region (AR) sources on the solar surface. CME kinematic properties, such as speed and angular width, are compared with AR magnetic field properties, such as magnetic flux, area, and neutral line characteristics. The resulting LOWCAT catalogue is also compared to the extensive AR property database created by the EU Horizon 2020 FLARECAST project, which provides more complex magnetic field parameters derived from vector magnetograms. Initial statistical analysis has been undertaken on the new data to provide insight into the link between flare and CME events, and characteristics of eruptive ARs. Warning thresholds determined from analysis of the evolution of these parameters is shown to be a useful output for operational space weather purposes. Parameters of particular interest for further analysis include total unsigned flux, vertical current, and current helicity. The automated method developed to create the LOWCAT catalogue may also be useful for future efforts to develop operational CME forecasting.

Authors: Sophie A. Murray, Jordan A. Guerra, Pietro Zucca, Sung-Hong Park, Eoin P. Carley, Peter T. Gallagher, Nicole Vilmer, Volker Bothmer
Projects: None

Publication Status: in press (doi: 10.1007/s11207-018-1287-4)
Last Modified: 2018-03-28 11:36
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Flare forecasting at the Met Office Space Weather Operations Centre  

Sophie A. Murray   Submitted: 2017-03-21 04:05

The Met Office Space Weather Operations Centre produces 24/7/365 space weather guidance, alerts, and forecasts to a wide range of government and commercial end users across the United Kingdom. Solar flare forecasts are one of its products, which are issued multiple times a day in two forms; forecasts for each active region on the solar disk over the next 24 hours, and full-disk forecasts for the next four days. Here the forecasting process is described in detail, as well as first verification of archived forecasts using methods commonly used in operational weather prediction. Real-time verification available for operational flare forecasting use is also described. The influence of human forecasters is highlighted, with human-edited forecasts outperforming original model results, and forecasting skill decreasing over longer forecast lead times.

Authors: Sophie A. Murray, Suzy Bingham, Michael Sharpe, David Jackson
Projects: None

Publication Status: Accepted for publication in Space Weather
Last Modified: 2017-03-22 05:26
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Evidence for Partial Taylor Relaxation from Changes in Magnetic Geometry and Energy during a Solar Flare  

Sophie A. Murray   Submitted: 2012-12-27 05:10

Solar flares are powered by energy stored in the coronal magnetic field, a portion of which is released when the field reconfigures into a lower energy state. Investigation of sunspot magnetic field topology during flare activity is useful to improve our understanding of flaring processes. Here we investigate the deviation of the non-linear field configuration from that of the linear and potential configurations, and study the free energy available leading up to and after a flare. The evolution of the magnetic field in NOAA region 10953 was examined using data from Hinode/SOT-SP, over a period of 12 hours leading up to and after a GOES B1.0 flare. Previous work on this region found pre- and post-flare changes in photospheric vector magnetic field parameters of flux elements outside the primary sunspot. 3D geometry was thus investigated using potential, linear force-free, and non-linear force-free field extrapolations in order to fully understand the evolution of the field lines. Traced field line geometrical and footpoint orientation differences show that the field does not completely relax to a fully potential or linear force-free state after the flare. Magnetic and free magnetic energies increase significantly ~ 6.5-2.5 hours before the flare by ~ 1031 erg. After the flare, the non-linear force-free magnetic energy and free magnetic energies decrease but do not return to pre-flare 'quiet' values. The post-flare non-linear force-free field configuration is closer (but not equal) to that of the linear force-free field configuration than a potential one. However, the small degree of similarity suggests that partial Taylor relaxation has occurred over a time scale of ~ 3-4 hours.

Authors: Sophie A. Murray, D. Shaun Bloomfield, Peter T. Gallagher
Projects: Hinode/SOT

Publication Status: Accepted for publication in Astronomy and Astrophysics
Last Modified: 2012-12-27 11:07
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The Evolution of Sunspot Magnetic Fields Associated with a Solar Flare  

Sophie A. Murray   Submitted: 2011-05-11 02:27

Solar flares occur due to the sudden release of energy stored inactive-region magnetic fields. To date, the pre-cursors to flaring are stillnot fully understood, although there is evidence that flaring is related tochanges in the topology or complexity of an active region's magnetic field.Here, the evolution of the magnetic field in active region NOAA 10953 wasexamined using Hinode/SOT-SP data, over a period of 12 hours leading up to andafter a GOES B1.0 flare. A number of magnetic-field properties and low-orderaspects of magnetic-field topology were extracted from two flux regions thatexhibited increased Ca II H emission during the flare. Pre-flare increases invertical field strength, vertical current density, and inclination angle of ~8degrees towards the vertical were observed in flux elements surrounding theprimary sunspot. The vertical field strength and current density subsequentlydecreased in the post-flare state, with the inclination becoming morehorizontal by ~7degrees. This behaviour of the field vector may provide aphysical basis for future flare forecasting efforts.

Authors: Sophie A. Murray, D. Shaun Bloomfield, Peter T. Gallagher
Projects: Hinode/SOT

Publication Status: Solar Physics (accepted)
Last Modified: 2011-05-11 09:12
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Abstracts by Author
Connecting Coronal Mass Ejections to Their Solar Active Region Sources: Combining Results from the HELCATS and FLARECAST Projects
Flare forecasting at the Met Office Space Weather Operations Centre
Evidence for Partial Taylor Relaxation from Changes in Magnetic Geometry and Energy during a Solar Flare
The Evolution of Sunspot Magnetic Fields Associated with a Solar Flare

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