Solar Magnetism and the Activity Telescope at HSOS

Zhang, Hongqi; Wang, Dongguang; Deng, Yuanyong; Hu, Keliang; Su, Jiangtao; Jiao, Lin; Ge, Lin; Yang, Shimo; Mao, Weijun; Wang, Yanan; Hu, Qi-Qian; Xue, Junsun; Lu, Haitian; Ni, Houkun; Chen, Hanliang; Zhou, Xiaojun; Zhu, Qingsheng; Yuan, Lü-Jun; Yong, Zhu

doi:10.1088/1009-9271/7/2/12

Cited by 45 publications

(22 citation statements)

References 9 publications

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“…Figure shows H α image data made at the HSOS [e.g., Zhang et al , ] over 3 days from 10 to 12 December 2013. A chain of faint dark structures was persistently seen in a line near the north pole.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…In this way, we indeed need a method to ascertain position of PIL, independently of the magnetic observations. To check the positions of PIL, a good observational reference is given from H observations [e.g., Duvall et al, 1977;Zhang et al, 2007]; the lower temperature plasma materials confined in probably twisted magnetic field structures along PIL can be visible as dark filament regions in a H image. Figure 11 shows H image data made at the HSOS [e.g., Zhang et al, 2007] over 3 days from 10 to 12 December 2013.…”

Section: Summary and Discussionmentioning

confidence: 99%

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Comparison of potential field solutions for Carrington Rotation 2144

2016

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We examined differences among the coronal magnetic field structures derived with the potential field source surface (PFSS) model for Carrington Rotation 2144, from 21 November to 19 December 2013. We used the synoptic maps of solar photospheric magnetic field from four observatories, the Huairou Solar Observing Station (HSOS), Global Oscillation Network Group (GONG), Helioseismic Magnetic Imager (HMI), and Wilcox Solar Observatory (WSO). We tested two smoothing methods, Gaussian and boxcar averaging, and correction of unbalanced net magnetic flux. The solutions of three‐dimensional coronal magnetic field are significantly different each other. An open‐field region derived with HSOS data agrees best with the corresponding coronal hole observed by Solar Dynamics Observatories/Atmospheric Imaging Assembly, while HMI data yielded best agreements with the near‐Earth OMNI database. The GONG data overall gave agreements as good as the HMI. The PFSS calculations using WSO data were least sensitive to the choices we examined in this work. Differences in PFSS solutions using different choices and parameters in smoothing imply that the photospheric magnetic field distributions with size of several degrees at midlatitude and low‐latitude regions can be decisive, at least, in the examined period. To better determine the global solar corona, therefore, further evaluation of influences from compact bipolar magnetic field is needed.

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Summary and Discussionmentioning

confidence: 99%

Comparison of potential field solutions for Carrington Rotation 2144

2016

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“…The upward boundary integration scheme can also be adapted to the case with a spherical boundary. By using the full disk observations of vector magnetograms [ UeNo et al , 2004; Zhang et al , 2007; Su and Zhang , 2007], it is possible to model the global or large‐scale structures of a coronal magnetic field with a spherical boundary and study their relationships to the coronal mass ejections (CMEs) [ Chen and Shibata , 2000; Chen et al , 2002; Zhang and Low , 2005; Zhou et al , 2006a, 2006b].…”

Section: Discussionmentioning

confidence: 99%

Nonlinear force‐free coronal magnetic field extrapolation scheme based on the direct boundary integral formulation

Wang

2008

J. Geophys. Res.

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[1] The boundary integral equation (BIE) method was first proposed by Yan and Sakurai (2000) and used to extrapolate the nonlinear force-free magnetic field in the solar atmosphere. Recently, Yan and Li (2006) improved the BIE method and proposed the direct boundary integral equation (DBIE) formulation, which represents the nonlinear force-free magnetic field by direct integration of the magnetic field on the bottom boundary surface. On the basis of this new method, we devised a practical calculation scheme for the nonlinear force-free field extrapolation above solar active regions. The code of the scheme was tested by the analytical solutions of Low and Lou (1990) and was applied to the observed vector magnetogram of solar active region NOAA 9077. The results of the calculations show that the improvement of the new computational scheme to the scheme of Yan and Li (2006) is significant, and the force-free and divergence-free constraints are well satisfied in the extrapolated fields. The calculated field lines for NOAA 9077 present the X-shaped structure and can be helpful for understanding the magnetic configuration of the filament channel as well as the magnetic reconnection process during the Bastille Day flare on 14 July 2000.Citation: He, H., and H. Wang (2008), Nonlinear force-free coronal magnetic field extrapolation scheme based on the direct boundary integral formulation,

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“…Huairou Solar Observing Station (HSOS) is one of the key stations of the National Astronomical Observatories, Chinese Academy of Sciences. It has been observing sunspots for many years (Zhang et al 2007). One of its telescopes can acquire the full-disk photospheric data and vector magnetic fields at the same time.…”

Section: Introductionmentioning

confidence: 99%

Automatic Recognition of Sunspots in HSOS Full-Disk Solar Images

Zhao

Deng

et al. 2016

Publ. Astron. Soc. Aust.

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A procedure is introduced to recognise sunspots automatically in solar full-disk photosphere images obtained from Huairou Solar Observing Station, National Astronomical Observatories of China. The images are first pre-processed through Gaussian algorithm. Sunspots are then recognised by the morphological Bot-hat operation and Otsu threshold. Wrong selection of sunspots is eliminated by a criterion of sunspot properties. Besides, in order to calculate the sunspots areas and the solar centre, the solar limb is extracted by a procedure using morphological closing and erosion operations and setting an adaptive threshold. Results of sunspot recognition reveal that the number of the sunspots detected by our procedure has a quite good agreement with the manual method. The sunspot recognition rate is 95% and error rate is 1.2%. The sunspot areas calculated by our method have high correlation (95%) with the area data from USAF/NOAA.

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Solar Magnetism and the Activity Telescope at HSOS

Cited by 45 publications

References 9 publications

Comparison of potential field solutions for Carrington Rotation 2144

Comparison of potential field solutions for Carrington Rotation 2144

Nonlinear force‐free coronal magnetic field extrapolation scheme based on the direct boundary integral formulation

Automatic Recognition of Sunspots in HSOS Full-Disk Solar Images

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