Swap Observations of the Long-Term, Large-Scale Evolution of the Extreme-Ultraviolet Solar Corona

Seaton, Daniel B.; Groof, A. De; Shearer, Paul; Berghmans, D.; Nicula, B.

doi:10.1088/0004-637x/777/1/72

Cited by 36 publications

(56 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One interesting characteristic of the M12 model is that the interchange reconnection is a gradual process, as in Edmondson et al (2009), which is consistent with the dynamics of the observed PS that lasted for several hours without any drastic changes (see Seaton et al 2013). According to Wang et al (2000), PS configurations store and gradually release the energy over several hours and maybe days.…”

Section: Conclusion and Discussionsupporting

confidence: 76%

See 1 more Smart Citation

Dynamics of the Transition Corona

Masson

McCauley

Golub

et al. 2014

ApJ

View full text Add to dashboard Cite

Magnetic reconnection between the open and closed magnetic fields in the corona is believed to play a crucial role in the corona/heliosphere coupling. At large scale, the exchange of open/closed connectivity is expected to occur in pseudo-streamer (PS) structures. However, there is neither clear observational evidence of how such coupling occurs in PSs, nor evidence for how the magnetic reconnection evolves. Using a newly developed technique, we enhance the off-limb magnetic fine structures observed with the Atmospheric Imaging Assembly and identify a PS-like feature located close to the northern coronal hole. We first identify that the magnetic topology associated with the observation is a PS, null-point (NP) related topology bounded by the open field. By comparing the magnetic field configuration with the EUV emission regions, we determined that most of the magnetic flux associated with plasma emission are small loops below the PS basic NP and open field bounding the PS topology. In order to interpret the evolution of the PS, we referred to a three-dimensional MHD interchange reconnection modeling the exchange of connectivity between small closed loops and the open field. The observed PS fine structures follow the dynamics of the magnetic field before and after reconnecting at the NP obtained by the interchange model. Moreover, the pattern of the EUV plasma emission is the same as the shape of the expected plasma emission location derived from the simulation. These morphological and dynamical similarities between the PS observations and the results from the simulation strongly suggest that the evolution of the PS, and in particular the opening/closing of the field, occurs via interchange/slipping reconnection at the basic NP of the PS. Besides identifying the mechanism at work in the large-scale coupling between the open and closed fields, our results highlight that interchange reconnection in PSs is a gradual physical process that differs from the impulsive reconnection of the solar-jet model.

show abstract

Section: Conclusion and Discussionsupporting

confidence: 76%

“…The shape of the open strands shows a diverging pattern, as do the fanlike structures identified in EUV wavelengths in the low corona (Habbal et al 2011;Seaton et al 2013). In addition, at the intersection of the closed and open flux, we notice a thin extended region that becomes brighter and thinner as the system evolves.…”

mentioning

confidence: 78%

Dynamics of the Transition Corona

Masson

McCauley

Golub

et al. 2014

ApJ

View full text Add to dashboard Cite

show abstract

“…Red/blue shading shows Br on r = R ⊙ (saturated at ±50 G). Panel (h) shows an EUV 174Å image of the real corona from PROBA2/SWAP (with median stacking and stray-light correction as described by Seaton et al 2013). Panel (i) shows an image of the corona in the Fe XIV 5305Å line from the Habbal eclipse expedition, processed by the MGN algorithm of Morgan and Druckmüller (2014) (with parameter h = 0.9) to bring out the streamer structure.…”

Section: Plane-of-sky Magnetic Structurementioning

confidence: 99%

Global Non-Potential Magnetic Models of the Solar Corona During the March 2015 Eclipse

et al. 2018

Self Cite

View full text Add to dashboard Cite

Seven different models are applied to the same problem of simulating the Sun's coronal magnetic field during the solar eclipse on 2015 March 20. All of the models are non-potential, allowing for free magnetic energy, but the associated electric currents are developed in significantly different ways. This is not a direct comparison of the coronal modelling techniques, in that the different models also use different photospheric boundary conditions, reflecting the range of approaches currently used in the community. Despite the significant differences, the results show broad agreement in the overall magnetic topology. Among those models with significant volume currents in much of the corona, there is general agreement that the ratio of total to potential magnetic energy should be approximately 1.4. However, there are significant differences in the electric current distributions; while static extrapolations are best able to reproduce active regions, they are unable to recover sheared magnetic fields in filament channels using currently available vector magnetogram data. By contrast, time-evolving simulations can recover the filament channel fields at the expense of not matching the observed vector magnetic fields within active regions. We suggest that, at present, the best approach may be a hybrid model using static extrapolations but with additional energization informed by simplified evolution models. This is demonstrated by one of the models.

show abstract

“…The wellknown AR bands are clearly defined, as well as the tendency for CHs to appear at high latitudes. Moreover, the North-South assymetry corresponding to the ascending phase of Solar Cycle 24 during 2010-2014 is noticeable in the CH and AR latitude distributions (Seaton et al 2013). The AR latitude distribution for the segmentations using the SPoCA mask is slightly more peaked because this mask selects the core AR and their latitudinal extent is thus reduced.…”

Section: Distribution Estimation Using Em-schemementioning

confidence: 99%

Supervised classification of solar features using prior information

Visscher

Delouille

Dupont

et al. 2015

J. Space Weather Space Clim.

View full text Add to dashboard Cite

Context: The Sun as seen by Extreme Ultraviolet (EUV) telescopes exhibits a variety of large-scale structures. Of particular interest for space-weather applications is the extraction of active regions (AR) and coronal holes (CH). The next generation of GOES-R satellites will provide continuous monitoring of the solar corona in six EUV bandpasses that are similar to the ones provided by the SDO-AIA EUV telescope since May 2010. Supervised segmentations of EUV images that are consistent with manual segmentations by for example space-weather forecasters help in extracting useful information from the raw data. Aims: We present a supervised segmentation method that is based on the Maximum A Posteriori rule. Our method allows integrating both manually segmented images as well as other type of information. It is applied on SDO-AIA images to segment them into AR, CH, and the remaining Quiet Sun (QS) part. Methods: A Bayesian classifier is applied on training masks provided by the user. The noise structure in EUV images is nontrivial, and this suggests the use of a non-parametric kernel density estimator to fit the intensity distribution within each class. Under the Naive Bayes assumption we can add information such as latitude distribution and total coverage of each class in a consistent manner. Those information can be prescribed by an expert or estimated with an Expectation-Maximization algorithm. Results: The segmentation masks are in line with the training masks given as input and show consistency over time. Introduction of additional information besides pixel intensity improves upon the quality of the final segmentation. Conclusions: Such a tool can aid in building automated segmentations that are consistent with some ground truth' defined by the users.

show abstract

Swap Observations of the Long-Term, Large-Scale Evolution of the Extreme-Ultraviolet Solar Corona

Cited by 36 publications

References 35 publications

Dynamics of the Transition Corona

Dynamics of the Transition Corona

Global Non-Potential Magnetic Models of the Solar Corona During the March 2015 Eclipse

Supervised classification of solar features using prior information

Contact Info

Product

Resources

About