Journal cover Journal topic
Annales Geophysicae Sun, Earth, planets, and planetary systems An interactive open-access journal of the European Geosciences Union
Ann. Geophys., 32, 83-90, 2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Regular paper
12 Feb 2014
Ion drift simulation of sudden appearance of sub-keV structured ions in the inner magnetosphere
M. Yamauchi1, Y. Ebihara2, H. Nilsson1, and I. Dandouras3,4 1Swedish Institute of Space Physics (IRF), Box 812, 98128 Kiruna, Sweden
2Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Japan
3CNRS, Institut de Recherche en Astrophysique et Planétologie (IRAP), BP 44346, 31028, Toulouse cedex 4, France
4University of Toulouse, UPS-OMP, IRAP, Toulouse, France
Abstract. Energy–latitude dispersed structured sub-keV ions in the inner magnetosphere often show significant development or intensification (by more than factor of 3) within 1–2 h near noon or afternoon where the azimuthal ion drift velocity at the sub-keV range is expected to be near zero. To examine whether such sudden appearances in the dayside can be explained by the drift motion of ions that are formed during substorm-related injections, we numerically simulated two such examples, one at noon and the other in the afternoon, based on the ion drift model. For both cases, the ion drift model with finite duration of proton source in the nightside can explain the observed large inbound–outbound differences in the sub-keV proton population without any new sources. Ion drift motion can thus cause rapid changes of complicated ion populations, at remote places from the source a long time after the substorm activities.

Citation: Yamauchi, M., Ebihara, Y., Nilsson, H., and Dandouras, I.: Ion drift simulation of sudden appearance of sub-keV structured ions in the inner magnetosphere, Ann. Geophys., 32, 83-90,, 2014.
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