Multiple Convection Cells Induced by In‐Front and Off‐Front Interactions Between the Obliquely Northward IMF and the Geomagnetic Field

• Published in: Journal of geophysical research. Space physics 2024-06, Vol.129 (6), p.n/a
• Main Authors: Tanaka, T., Ebihara, Y., Watanabe, M., Fujita, S., Kataoka, R.
• Format: Article
• Language: English
• Subjects: Convection; Convection cells; Cusps; Geomagnetic field; HCA; interchange reconnection; Interplanetary magnetic field; Ionosphere; Magnetic fields; Magnetopause; Magnetospheres; Magnetospheric convection; Magnetospheric-solar wind relationships; nightside cell; northward IMF; null‐separator structure; Polar caps; Separators; Solar wind
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1029/2023JA031994

From the global simulation, we reproduce the solar wind‐magnetosphere‐ionosphere (S‐M‐I) interaction under the northward interplanetary magnetic field (IMF) with negative By. Reconnection structures, the plasma sheet, and lobes are formed in magnetospheric convection, while lobe/round‐merging/reciprocal/nightside cells appear in the ionosphere. Associated with the S‐M interaction, northern open field is generated at the evening open‐closed (O/C) boundary, due to successive cusp and interchange reconnections (in round‐merging cell) or by Dungey‐type reconnection (in nightside cell). Corresponding interchange and Dungey‐type reconnections occur at the southern null. Dungey‐type reconnection at the same time generates southern open field on the outer‐most magnetopause. Open field injected into the northern polar cap/void/lobe constructs the open field part of the round‐merging and nightside cells. After open‐field convection in the lobe, reclosures occur by again successive cusp and interchange reconnections on the dayside separator, or separator reconnection on the nightside separator. Former closed field line proceeds toward the evening O/C boundary through the dayside closed‐field convection in the round‐merging cell, while latter closed field line through the nightside closed‐field convection in the nightside cell. Shear that causes the large‐scale sun‐aligned arc is generated by the process of injecting open magnetic field into the void and the conjugate of process of connecting return flux from the plasma sheet to the nightside cell in counter hemisphere. Key Points Under the northward IMF, the S‐M interaction has in front and off‐front components exciting the round‐merging cell and the nightside cell In the nightside cell, closed flux is formed at nightside separator and transported along the nightside cell to the flank where reopened The HCA is explained by shear structure presented in this paper, without adopting evening‐morning symmetrical convection as in the DLR