Earth's polar cap ionization patches lead to ion upflow

Friday, 19 December 2014: 4:30 PM
Qing-He Zhang1, Qiugang Zong2, Michael M Lockwood3, Jun Liang4, Bei-chen Zhang5, Joran Idar Moen6, Shunrong Zhang7, Yongliang Zhang8, J. Michael Ruohoniemi9, Evan G Thomas9, Ruiyuan Liu5, Malcolm W. Dunlop10, Huigen Yang5, Hongqiao Hu5, Yong Liu11 and Mark Lester12, (1)Shandong University at Weihai, Weihai, China, (2)Peking University, School of Earth and Space Sciences, Beijing, China, (3)University of Reading, Reading, Berkshire, United Kingdom, (4)Univ. of Calgary, Calgary, AB, Canada, (5)Polar Research Institute of China, Shanghai, China, (6)University of Oslo, Physics Department, Oslo, Norway, (7)MIT Haystack Observatory, Westford, MA, United States, (8)The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States, (9)Virginia Tech, Blacksburg, VA, United States, (10)Rutherford Appleton Laboratory, Didcot, United Kingdom, (11)Center for Space Science and Applied Research,Chinese Academy of Sciences, Beijing, China, (12)University of Leicester, Leicester, United Kingdom
The Earth constantly losses matter through ions escaping from the polar ionosphere. This makes the ionosphere as an important source of plasma for the magnetosphere and could modulate atmospheric isotope abundances on geological timescales, depending on what fraction of the upflowing ions subsequently return to the ionosphere and what fraction are ejected into interplanetary space. It has been proposed that the magnetosphere is dynamically modulated by the presence of the ionospheric ions, particularly heavy ions O+, during magnetic substorms and storms. The origin and formation mechanism of ionospheric ion upflow is, however, poorly understood, particularly under disturbed space weather conditions. We report simultaneous direct observations of ion upflow and a patch of ionization at the center of the polar cap region during a geomagnetic storm. Our observations indicate enhanced fluxes of upwelling Oions originate from the patch and were accelerated by the enhanced ambipolar electric field. This enhancement is caused by soft electron precipitations. Polar cap patches therefore provide an important source of upwelling ions for accelerations mechanisms at greater altitudes which can eject the ions. These observations give new insight into the processes of ionosphere-magnetosphere coupling and the potential loss of terrestrial water dissociation products into space which, although extremely slow in the case of Earth, may be significant for other planets and moons.