1) Group of Solar Eruptions
General Introduction
Solar eruptions, including coronal mass ejections (CMEs) and solar flares, are spectacular eruptive phenomena occurring in the solar atmosphere. They represent the strongest energy release process in the solar system, with sometimes catastrophic impact on the geo-space environment. Despite intensive investigations over past decades, the exact physical process initiating and driving the eruption remains not resolved.
During solar eruptions, a significant amount of magnetic energy is transformed into kinetic energy of energetic particles. It remains elusive regarding how particles are accelerated during solar eruptions (through shock or reconnection related processes). The energetic particles, especially the electrons, can excite various types of electro-magnetic emission enhancement through a number of different emitting mechanisms. Of particular interests are the radio bursts at the metric and centimeter (microwave) wavelengths, as well as the hard-X-ray and soft-X-ray emissions. They are important since they carry important information about the background coronal media and the energetic particles.
Thegroupexploresvarious aspects of solar eruptions,includingthe initiation and eruptive mechanisms of CMEs/flares, particle acceleration via shocks and magnetic reconnections, as well ascritical issuesrelevant to solar radio bursts and x-ray emissions. We arealsodeveloping state-of-the-art instrumentsobserving the sun viaradio wavelengths.
Principal Investigator: Prof. Dr. Yao Chen
Team Members (1 full professor, 4 associate professors, 1 associate researcher, 2 technician, 4 postdocs, and 7 graduate students)
Full Professor:Dr. Hongqiang Song
Associate Professor:Dr. Chaoling Tang, Dr. Maoshui Lv, Dr. Guiping Ruan, Mr. Qingfu Du
Associate Researcher:Dr. Ruisheng Zheng
Lecturer:Miss Junrui Zhang
Technician:Dr. Shiwei Feng, Mr. Zhao Wu (also a phd student)
Postdoctoral Scientists:Vasanth V., Artem Koval, Chunlin Tian, Xiangliang Kong
Graduate students:Guohui Du, Zhao Wu, Bing Wang, Guang Lu, Chuanyang Li, Di Zhao, Hao Ning
2) Research Group of Solar atmospheric physics and Coronagraph Technology Development
Solar atmospheric physics
The solar atmosphere is the part of the Sun above its convective zone, consisting of photosphere, chromosphere, transition region and corona. It is the source of space weather that concerns with the time varying conditions within the Solar System, including the solar wind that is a stream of charged particles released from the upper atmosphere of the Sun. Therefore, to understand the formation and the variation of the space weather, one has to trace back to the solar atmosphere and the knowledge of the physics of that region is crucial. In another hand, the solar atmosphere is also a unique physics laboratory where we can study in detail the interaction between the plasma and the magnetic field over a variety of spatial and temporal scales that cannot be reproduced in laboratory.
Our research
The group mainly focuses on two major problems: coronal heating and origin of the solar wind. The coronal heating problem relates to the question why the temperature of the Sun's corona is millions of degree higher than that of the photosphere. Since the second law of thermodynamics prevents heat conduction directly from the solar photosphere, the high temperatures require energy to be carried from the solar interior to the corona by non-thermal processes. The solar wind origin problem is the question how the supersonic streams of charged particles are released from the upper atmosphere of the Sun and how they are accelerated in their source regions.
To study the above problems, the team mainly concentrates on the observational aspect. One division works on data analyses that focus on small-scale dynamic events in the solar atmosphere relating to the coronal heating and the source region of the solar wind. Another division of the team aims at development of large-angle white-light coronagraph.
Principal Investigator: Prof. Dr. Lidong Xia
Team Members (2 associateresearcher, 1 Lecturer,2postdoc, and4graduate students)
AssociateResearcher:Dr. Weixin Liu,Dr. Zhenghua Huang
Lecturer:Dr. Hui Fu
Postdoctoral Scientists:Dr. Mingzhe Sun,Dr. Kalogodu Chadraschekah
Graduate students:Chaozou Mou, Zhenyong Hou, Rui Ding, Youqian Qi
3) Research group on the physics of the solar corona and solar wind
Research Interests
How is the Sun’s atmosphere heated to multi-million degrees Kelvin? Despite its long history, this question still remains to be addressed. While the ultimate energy source is undoubtedly due to mechanical motions in the convection zone, there is no consensus as to how this energy is channeled to and then deposited in the solar atmosphere. With the availability of high-cadence, high-spatial-resolution instruments such as Hinode/SOT, SDO/AIA and IRIS, there has arisen an idea that magnetohydrodynamic (MHD) waves are the sought-after energy carrier, and solar atmospheric heating is then a result of their energy being transformed into heat. Indeed, observations indicate that the energy flux density carried by various waves is sufficient from the energy budget perspective.
The applicability of a wave-heating scenario hinges on a number of things. First, their energy-carrying capability is sensitive to the physical parameters of magnetized structures hosting these waves. These parameters are, however, not easy to directly measure. Second, different wave modes need to be dissipated in different ways. A pre-requisite is then to identify the nature of waves in various structures on the Sun. For this purpose, theories of MHD waves accounting for the highly inhomogeneous nature of the Sun’s atmosphere are needed but are far from complete.
Our group adopts the following approaches to address the issue of solar atmospheric heating.
lWe develop MHD wave theories that incorporate such effects as transverse and longitudinal structuring. This is then followed by applications of wave theories to the inference of solar atmospheric parameters.
lWe conduct analytical and numerical studies on MHD waves in the highly structured solar atmosphere to examine their generation, propagation and dissipation.
With the solar corona reaching temperatures over a million Kelvin, the solar atmosphere in open magnetic field regions cannot stay static but will expand. This coronal expansion, or more precisely the solar wind, is actually a result of solar atmospheric heating. Nonetheless, the solar wind itself is also an important subject to work on, given their rich measurements made both in situ and from remote-sensing. A popular idea is that while propagating outwards, MHD waves somehow become turbulent, and their energy is then picked up by solar wind species.
Our group has developed, in collaboration with others, a multi-fluid MHD code for the solar corona and solar wind. We treat different species on an equal footing by solving their transport equations. The methodology is that, with a given description for turbulence, we can then ask whether our model output can reproduce solar wind measurements. In this sense, the multi-fluid code can be seen as a quantitative testbed of turbulence theory.
Group Members
Head: Prof. Dr. Bo Li
Faculty members:Dr. Shaoxia Chen, Dr. Hui Yu
Postdoctoral Scientists:Dr. Chong Huang
Graduate students:Haixia Xie, Mingzhe Guo, Zhipeng Wangguan
4) Group of Solar Wind-Magnetosphere Interaction
General Introduction
The interaction between the solar wind and Earth’s magnetosphere, and the geospace effects that result, comprise a fundamental driver of space weather. Understanding how this vast system works requires knowledge of energy and mass transport, and coupling between different regions.
We use multi-point data from spacecraft such as CLUSTER, Double Star, THEMIS, ARTEMIS and MMS as well as ground based magnetic field and remote sensing data to study the solar wind mass, momentum, and energy transport into the Earth’s magnetosphere. Using our unique multi-point data analysis techniques and other data analysis/simulation tools, we analyze spatial-temporal structures in space, their formation mechanisms, and their possible influence on space weather. The group has also carried out some study on planet magnetosphere and the solar wind/magnetpsphere interaction with the earth’s moon related to the lunar water formation. Our team members have been involved in various future space missions such as SMILE by acting as one of its scientific team members.
Principal Investigator: Prof. Dr. Quanqi Shi
Team Members (1 associate professor, 1 Lecturer,1Visiting Researcher,1postdoc, and5graduate students)
Associate Professor:Dr. Dimitry Pokhotelov
Lecturer:Dr. Anmin Tian
Visiting Researcher:Dr. MotoharuNowada
Postdoctoral Scientists:Dr. Bagrat Mailyan
Graduate students:XiaochenShen,Shichen Bai, Shutao Yao,Huizi Wang, Shuai Zhang
5) Group of Polar ionosphere-magnetosphere coupling
General Introduction
The polar region is one of the most dynamical regions on Earth, where the Earth’s magnetic field lines are highly convergent, nearly vertical, and open to interplanetary space. In this region, energy, mass and momentum from the solar wind can directly enter into the polar upper atmosphere, and various dynamical processes generated by the solar wind-magnetosphere coupling can be directly mapped to the polar ionosphere. This results in various features specific to the polar ionosphere, such as aurora actives, storm enhanced density (SED)/tongue of ionization (TOI), polar cap patches, polar cap arcs, etc. They are also directly subject to space weather disturbances and link to magnetosphere-ionosphere-thermosphere (M-I-T) coupling processes. Despite intensive investigations over past decades, the exact formation and evolution physical process and associated scintillations generation mechanisms, especially under disturbed space weather conditions, remains not resolved.
With the fast development of coverage in the polar regions during recent years from the multiple instruments, such as GNSS ground-based receivers, incoherent scatter radars (ISRs), Super Dual Auroral Radar Network (SuperDARN), and all sky imagers as well as space-based measurements, a wealth of data on the global distributions of plasma and flows, as well as the associated scintillations are now available. This offers an excellent opportunity to study these polar irregularities, such as polar cap patches and aurora, and to understand in detail the M-I-T coupling processes within a global perspective.
The group focuses on various features specific to the polar ionosphere and aims to understand the dynamical processes associated with these irregularities and their impact on M-I-T coupling processes, through coordinated investigations of multiple ground-based and space-based observations (including data from GNSS Receivers, ISRs, SuperDARN, all sky imagers, MMS / THEMIS / Cluster / DMSP / SWARM satellites, etc.) and impact of these irregularities on GNSS navigation and communications, as well as scintillation modeling and forecasts. We have also built a geomagnetic observatory of Shandong University, Weihai (SDW) with the magnetometer (LEMI-018) and installed the GPS ionospheric scintillation and TEC monitors (GPStaion_6).
Principal Investigator: Prof. Dr. Qing He Zhang
Team Members (1lecturer,1postdocs, and3graduate students)
Lecturer:Dr. Zanyang Xing
Postdoctoral Scientists:Shishir Priyadarshi
Graduate students:Yong Wang, Yuzhang Ma, Yanqiu Ren
