Unusual shrinkage and reshaping of Earth’s magnetosphere under a strong northward interplanetary magnetic field
- 1Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, Shandong 264209, China
- 2State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190, China
- 3The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland 20723, USA
- 4Birkeland Centre for Space Science, Department of Physics and Technology, University of Bergen, Bergen N-5020, Norway
- 5The University Centre in Svalbard, N-9171 Longyearbyen, Norway
- 6Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095, USA
- 7Department of Meteorology, University of Reading, Reading RG6 6BB, UK
- 8School of Earth and Space Sciences, Peking University, 100190 Beijing, China
- 9Lab of BLOS Reliable Information Transmission, Chongqing University of Posts and Telecommunications, Chongqing 400000, China
Open magnetic flux in the polar cap almost completely disappeared and the Earth's magnetotail was compressed into a calabash shape during the 9th April 2015 coronal mass ejection, according to magnetohydrodynamic simulations and observations from DMSP and THEMIS.The Earth's magnetosphere is the region of space where plasma behavior is dominated by the geomagnetic field. It has a long tail typically extending hundreds of Earth radii (R-E) with plentiful open magnetic fluxes threading the magnetopause associated with magnetic reconnection and momentum transfer from the solar wind. The open-flux is greatly reduced when the interplanetary magnetic field points northward, but the extent of the magnetotail remains unknown. Here we report direct observations of an almost complete disappearance of the open-flux polar cap characterized by merging poleward edges of a conjugate horse-collar aurora (HCA) in both hemispheres' polar ionosphere. The conjugate HCA is generated by particle precipitation due to Kelvin-Helmholtz instability in the dawn and dusk cold dense plasma sheets (CDPS). These CDPS are consist of solar wind plasma captured by a continuous dual-lobe magnetic reconnections, which is further squeezed into the central magnetotail, resulting in a short "calabash-shaped" magnetotail.
How to cite: Wang, X., Zhang, Q., Wang, C., Zhang, Y., Tang, B., Xing, Z., Oksavik, K., Lyons, L. R., Lockwood, M., Zong, Q., Li, G., Liu, J., Ma, Y., and Wang, Y.: Unusual shrinkage and reshaping of Earth’s magnetosphere under a strong northward interplanetary magnetic field, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11173, https://doi.org/10.5194/egusphere-egu24-11173, 2024.
