1. Department of Geophysics, College of the Geology Engineering and Geomatics; Chang'an University; Xi'an China
2. Key Laboratory of Geospace Environment, Chinese Academy of Sciences; University of Science and Technology of China; Hefei China
3. Mengcheng National Geophysical Observatory, School of Earth and Space Sciences; University of Science and Technology of China; Hefei China
4. Harvard-Smithsonian Center for Astrophysics; Cambridge MA USA
5. Gravity and Magnetic Institute; Chang'an University; Xi'an China
6. Key Laboratory of Western China's Mineral Resources and Geological Engineering; China Ministry of Education; Xi'an China
7. Key Laboratory of Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics; Chinese Academy of Sciences; Beijing China