Two-dimensional (2D) solar coronal magnetogram is difficult to be measured directly until now. From the previous knowledge, a general relation has been noticed that the brighter green-line brightness for corona, the higher coronal magnetic field intensity may correspond to. To try to further reveal the relationship between coronal green line brightness and magnetic field intensity, we use the 2D coronal images observed by Yunnan Observatories Green-line Imaging System (YOGIS) of the 10 cm Lijiang coronagraph and the coronal magnetic field maps calculated from the current-free extrapolations with the photospheric magnetograms taken by Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) spacecraft. In our analysis, we identified the coronal loop structures and construct two-dimensional maps of the corresponding magnetic field intensity in the plane of the sky (POS) above the limb. We derive the correlation coefficients between the coronal brightness and the magnetic field intensity for different heights of coronal layers. We further use a linear combination of a Gaussian and a quadratic profile to fit the correlation coefficients distribution, finding a largest correlation coefficient of 0.82 near 1.1 R _⊙ (solar radii) where is almost the top of the closed loop system. For the small closed loop system identified, the correlation coefficient distributions crossing and covering the loop are calculated. We also investigate the correlation with extended heliocentric latitude zones and long period of one whole Carrington Rotation, finding again that the maximum correlation coefficient occurs at the same height. It is the first time for us to find that the correlation coefficients are high (all are larger than 0.8) at the loop-tops and showing poor correlation coefficients with some fluctuations near the feet of the coronal loops. Our findings indicate that, for the heating of the low-latitude closed loops, both DC (dissipation of currents) and AC (dissipation of Alfvén and magnetosonic waves) mechanisms should act simultaneously on the whole closed loop system while the DC mechanisms dominate in the loop-top regions. Therefore, in the distributions of the correlation coefficients with different heights of coronal layers, for both large- and small-scale latitude ranges, the coefficients can reach their maximum values at the same coronal height of 1.1 R _⊙ , which may indicate the particular importance of the height of closed loops for studying the coupling of the local emission mechanism and the coronal magnetic fields, which maybe helpful for studying the origin of the low-speed solar wind.

The intensity of the green line (Fe xiv 5303 Å) is the strongest in the visible spectrum of the solar corona, and this line has been used as long-term powerful diagnostic tools for studying the coronal configurations and hot plasma dynamics. However, it remains unclear and an open question whether there exists close relationship between the green line intensities and the coronal extreme ultraviolet (EUV) line emissions for various coronal structures. In this paper, we use the green-line data by the Lijiang YOGIS Lyot coronagraph and the EUV data from the Solar Dynamics Observatory/Atmospheric Imaging Assembly instruments in order to perform direct comparisons and analyses, based on two algorithms developed to extract particular features in the low corona. It is found that, among the correlation coefficients obtained between the intensities of 5303 Å and the EUV lines, the coefficients between the green line and the 211 Å wavelength for different coronal structures and different limb locations always keep the highest values (ranging from 0.89 to 0.99), which has not been reported before. This result can be helpful and promising to link together the various physical processes involved at different heights in the corona by precisely tracking the bright loops or other features observed in 5303 Å above the limb down to the correct surface locations revealed by the 211 Å data. Furthermore, the ground-based observations of the coronal green line and the space-based EUV observations at 211 Å can advantageously complement each other when there is a need.

About ten years ago, we established the first coronagraph that has been continuously operating on the high plateau of western China. This coronagraph is an internal occulting, 10 cm aperture instrument, installed at Lijiang Station through a collaboration with the Norikura Station of the National Astronomical Observatory of Japan. To ensure high efficiency in current and future coronal observations, developing integrated observation systems is essential for reliable, autonomous, and remote operation of coronagraphs. This paper introduces an advanced integrated observation and control system, based on the Lijiang 10 cm coronagraph. The coronagraph focuses on the observations for the solar inner corona, capturing the coronal green-line emission within a field range from $1.03R_{⨀}$ to $2.5R_{⨀}$. To enhance the observational precision and efficiency, a comprehensive integrated system has been designed, incorporating various subsystems, including precise pointing and tracking mechanisms, a multi-band filter system, a protective dome system, and a robust data storage infrastructure. This paper details the hardware architecture and software frameworks supporting each subsystem. Results from extended operational testing confirm the stability of the system, its capacity for autonomous and remote observations, and significant improvements in the automation and efficiency of coronal imaging. The automated observation system will be further improved and used for our future coronagraphs to be developed for coronal magnetism diagnosis.

A few ground-based solar coronagraphs have been installed in western China for observing the low-layer corona in recent years. However, determining the helioprojective coordinates for the coronagraphic data with high precision is an important but challenging step for further research with other multiwavelength data. In this paper, we propose an automatic coronal image registration method that combines local statistical correlation and feature point matching to achieve accurate registration between ground-based coronal green-line images and space-based 211 Å images. Then, the accurate field of view information of the coronal green-line images can be derived, allowing the images to be mapped to the helioprojective Cartesian coordinates with an accuracy of no less than 0 . ″ 1 . This method has been extensively validated using 100 days of coronal data spanning an 11 yr period, demonstrating its broad applicability to ground-based coronagraphs equipped with green-line observations. It significantly enhances the scientific value of ground-based coronal data, enabling comprehensive studies of coronal transient activities and facilitating the joint analysis of data from multiple instruments. Additionally, it holds potential for future applications in improving the pointing accuracy of coronagraphs.

The coronal is the origins of large-scale solar activity and disastrous space weather, it contains extremely rich information and various physical processes. The coronal loop is a kind of bright structure with hot plasma which is bounded by magnetic field in the coronal, it is a good reflection of the magnetic structure that we can hardly observe directly. It is also the energy channel between the photosphere and coronal, and the study of coronal loop is helpful for us to understand the magnetic line foot movement.