A tool to diagnose magnetosphere under northward IMF conditions:
Simultaneous detections of TPA and omega-band aurora
Motoharu Nowada
Shandong Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Institute of Space Sciences, Shandong University, Weihai, Shandong, People's Republic of China.
Corresponding Author:moto.nowada@sdu.edu.cn
Author ProfileAbstract
In this study, we try to explore the feasibility on whether or not the
magnetospheric processes under northward Interplanetary Magnetic Field
(IMF) conditions can be diagnosed using two different auroral phenomena;
transpolar arc (TPA) and omega-band aurora. Both TPA and omega-band
aurora can occur during the northward IMF intervals, and their
appearances are closely related with the nightside magnetospheric
processes. TPA can be formed and grown by the field-aligned currents
induced by the plasma flow shear or the plasma vortex structures between
the fast plasma flows generated by magnetotail magnetic reconnection and
slower background magnetospheric flows, and the convection of the
reconnection-formed closed magnetic fluxes, which cause in the nightside
plasma sheet. On the other hand, the omega-band aurora can be attributed
to the Kelvin-Helmholtz instabilities triggered by the flow shear
between the plasma flows of the nightside magnetospheric boundary layer
such as low-latitude boundary layer (LLBL) and background magnetospheric
(plasma sheet) flows. If both auroral phenomena can simultaneously be
observed, we might remotely investigate (diagnose) how the plasma and
its energy are transported in the nightside magnetosphere and at the
magnetospheric boundary region under northward IMF conditions. We will
discuss the feasibility of this magnetospheric diagnosis, giving the
observational example(s) of simultaneous observations of two different
auroral phenomena, that is, TPA and omega-band aurora, and in-situ
magnetospheric observation(s). Keyword: 1. Transpolar arc and omega band
aurora 2. Solar wind-magnetotail-ionosphere coupling 3. Magnetospheric
diagnosis 4. Magnetospheric dynamics under northward IMF conditions