Three-dimensional Transient Magnetic Reconnection and Dipolarization Fronts in the Terrestrial Magnetotail

Friday, 18 December 2015
Poster Hall (Moscone South)
Meng Zhou1,2, Xiaohua Deng1, Maha Ashour-Abdalla3, Ye Pang1, Giovanni Lapenta4, Huishan Fu5, Raymond J Walker6, Shiyong Huang7 and Rongxin Tang1, (1)Nanchang University, Nanchang, China, (2)University of California Los Angeles, Los Angeles, CA, United States, (3)University of California Los Angeles, Physics and Astronomy, Los Angeles, CA, United States, (4)Katholieke Universiteit Leuven, Leuven, Belgium, (5)Beihang University, Space Science Institute, School of Astronautics, Beijing, China, (6)University of California Los Angeles, Earth, Planetary, and Space Sciences, Los Angeles, CA, United States, (7)Laboratoire de Physique des Plasmas, Saint-Maur Des Fossés Cedex, France
We report a Cluster observation of transient magnetic reconnection in the Earth’s magnetotail at the location of [Xgsm ~ -17.2 RE, Ygsm ~ -4.5 RE and Zgsm ~ 0]. The reconnection X-line retreated tailward with a speed of 34 km/s. An ion diffusion region with a weak guide field (~10% of the lobe field) was encountered during the flow reversal. Transient energetic electron beams, which directed away from the X-line, were detected repeatedly around the current sheet boundary layer with periods of about 60s during the tailward flow burst. On the earthward side of X-line, multiple earthward-propagating dipolarization fronts were observed quasi-periodically with time period of 60s-90s. Surprisingly the cross-tail sizes of some observed dipolarization fronts are only 1-2 ion inertial lengths. The X-line expanded across the tail in the electron flow direction with a speed about 0.03VA, here VA is the Alfven speed. Two spacecraft, which were separated in the cross-tail direction by 1 RE, observed distinct structures and different tones of reconnection, which implies that reconnection proceeds drastically different in different segments of X-line.