Global Solar Magnetic Field Evolution Over 4 Solar Cycles: Use of the McIntosh Archive

Webb, D. F.; Gibson, S. E.; Hewins, Ian; McFadden, Robert; Emery, B. A.; Malanushenko, Anna; Kuchar, T. A.

doi:10.3389/fspas.2018.00023

Cited by 26 publications

(20 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hα filaments and filament channels represent polarity inversion lines that trace boundaries of the large-scale patterns above underlying photospheric UMRs. The Hα synoptic maps display polarity inversion lines that outline boundaries of large- scale magnetic field (Makarov et al 1983;Pevtsov et al 2016;Webb et al 2018). The Hα maps agree with synoptic magnetograms (Snodgrass et al 2000).…”

Section: Model and Data Analysessupporting

confidence: 56%

Long-Term Evolution of the Sun's magnetic field during Cycles 15--19 based on their proxies from Kodaikanal Solar Observatory

Mordvinov,

Karak,

Banerjee

et al. 2020

Preprint

View full text Add to dashboard Cite

The regular observation of the solar magnetic field is available only for about last five cycles. Thus, to understand the origin of the variation of the solar magnetic field, it is essential to reconstruct the magnetic field for the past cycles, utilizing other datasets. Long-term uniform observations for the past 100 years as recorded at the Kodaikanal Solar Observatory (KoSO) provide such opportunity. We develop a method for the reconstruction of the solar magnetic field using the synoptic observations of the Sun's emission in the Ca II K and Hα lines from KoSO for the first time. The reconstruction method is based on the facts that the Ca II K intensity correlates well with the unsigned magnetic flux, while the sign of the flux is derived from the corresponding Hα map which provides the information of the dominant polarities. Based on this reconstructed magnetic map, we study the evolution of the magnetic field in Cycles 15-19. We also study bipolar magnetic regions (BMRs) and their remnant flux surges in their causal relation. Time-latitude analysis of the reconstructed magnetic flux provides an overall view of magnetic field evolution: emergent magnetic flux, its further transformations with the formation of unipolar magnetic regions (UMRs) and remnant flux surges. We identify the reversals of the polar field and critical surges of following and leading polarities. We found that the poleward transport of opposite polarities led to multiple changes of the dominant magnetic polarities in poles. Furthermore, the remnant flux surges that occur between adjacent 11-year cycles reveal physical connections between them.

show abstract

Section: Model and Data Analysessupporting

confidence: 56%

Long-Term Evolution of the Sun's magnetic field during Cycles 15--19 based on their proxies from Kodaikanal Solar Observatory

Mordvinov,

Karak,

Banerjee

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Solar coronal holes are usually identified from (1) EUV or X-ray images reflecting the density distribution of highly ionized ions in the solar corona (Vršnak et al 2007;Rotter et al 2012;Krista & Gallagher 2009;Verbeeck et al 2014;Lowder et al 2014;Garton et al 2018;Illarionov & Tlatov 2018;Hamada et al 2018), (2) He I 10 830 Å images probing the solar chromosphere (Henney & Harvey 2005;Tlatov et al 2014;Webb et al 2018), or (3) magnetic field extrapolations (Pomoell & Poedts 2018;Pizzo et al 2011;Asvestari et al 2019;Jeong et al 2020). In EUV and soft X-ray images, coronal holes appear as distinct dark features because of their reduced density and temperature.…”

Section: Introductionmentioning

confidence: 99%

Multi-channel coronal hole detection with convolutional neural networks

Jarolim

Veronig

Hofmeister

et al. 2021

A&A

View full text Add to dashboard Cite

Context. A precise detection of the coronal hole boundary is of primary interest for a better understanding of the physics of coronal holes, their role in the solar cycle evolution, and space weather forecasting. Aims. We develop a reliable, fully automatic method for the detection of coronal holes that provides consistent full-disk segmentation maps over the full solar cycle and can perform in real-time. Methods. We use a convolutional neural network to identify the boundaries of coronal holes from the seven extreme ultraviolet (EUV) channels of the Atmospheric Imaging Assembly (AIA) and from the line-of-sight magnetograms provided by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). For our primary model (Coronal Hole RecOgnition Neural Network Over multi-Spectral-data; CHRONNOS) we use a progressively growing network approach that allows for efficient training, provides detailed segmentation maps, and takes into account relations across the full solar disk. Results. We provide a thorough evaluation for performance, reliability, and consistency by comparing the model results to an independent manually curated test set. Our model shows good agreement to the manual labels with an intersection-over-union (IoU) of 0.63. From the total of 261 coronal holes with an area > 1.5 • 10 10 km 2 identified during the time-period from November 2010 to December 2016, 98.1% were correctly detected by our model. The evaluation over almost the full solar cycle no. 24 shows that our model provides reliable coronal hole detections independent of the level of solar activity. From a direct comparison over short timescales of days to weeks, we find that our model exceeds human performance in terms of consistency and reliability. In addition, we train our model to identify coronal holes from each channel separately and show that the neural network provides the best performance with the combined channel information, but that coronal hole segmentation maps can also be obtained from line-of-sight magnetograms alone. Conclusions. The proposed neural network provides a reliable data set for the study of solar-cycle dependencies and coronal-hole parameters. Given the fast and robust coronal hole segmentation, the algorithm is also highly suitable for real-time space weather applications.

show abstract

“…All these quantities are good tracers of solar activity that permit us to probe the properties of the solar cycle (amplitude, duration, activity level). The accumulation of such data series and products over very long periods is thus essential to study and improve our understanding of the solar cycle variability and modulation (including the Gleissberg modulation or the occurrence of grand minima such as the Maunder minimum; e.g., Clette et al, 2015;Webb et al, 2018), both of which directly affect space weather.…”

Section: Long-term Low-cadence Chromospheric Observationsmentioning

confidence: 99%

Optical instrumentation for chromospheric monitoring during solar cycle 25 at Paris and Côte d’Azur observatories

Malherbe

Corbard

Dalmasse

2020

J. Space Weather Space Clim.

View full text Add to dashboard Cite

We present the observing program proposed by Paris and Cote d'Azur Observatories for monitoring solar activity during the upcoming cycle 25 and providing near real time images and movies of the chromosphere for space-weather research and applications. Two optical instruments are fully dedicated to this task and we summarize their capabilities. Short-term and fast-cadence observations of the chromosphere will be performed automatically at Calern observatory (Cote d'Azur), where dynamic events, as flare development, Moreton waves, filament instabilities and Coronal Mass Ejections onset, will be tracked. This new set of telescopes will operate in 2021 with narrow bandpass filters selecting Halpha and CaII K lines. We present the instrumental design and a simulation of future images. At Meudon, the Spectroheliograph is well adapted to the long-term and low-cadence survey of chromospheric activity by recently improved and optimized spectroscopic means. Surface scans deliver daily (x, y, lambda) datacubes of Halpha, CaII K and CaII H line profiles. We describe the nature of available data and emphasize the new calibration method of spectra.

show abstract

Global Solar Magnetic Field Evolution Over 4 Solar Cycles: Use of the McIntosh Archive

Cited by 26 publications

References 58 publications

Long-Term Evolution of the Sun's magnetic field during Cycles 15--19 based on their proxies from Kodaikanal Solar Observatory

Long-Term Evolution of the Sun's magnetic field during Cycles 15--19 based on their proxies from Kodaikanal Solar Observatory

Multi-channel coronal hole detection with convolutional neural networks

Optical instrumentation for chromospheric monitoring during solar cycle 25 at Paris and Côte d’Azur observatories

Contact Info

Product

Resources

About