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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. A11, 1406, doi:10.1029/2002JA009342, 2002

Magnetospheric responses to sudden and quasiperiodic solar wind variations

K.-H. Kim

School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota, USA


C. A. Cattell

School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota, USA


D.-H. Lee

Department of Astronomy and Space Science, Kyung Hee University, Kyunggi, Korea


K. Takahashi

Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland, USA


K. Yumoto

Department of Earth and Planetary Sciences, Kyushu University, Hakozaki, Japan


K. Shiokawa

Solar-Terrestrial Environment Laboratory, Nagoya University, Toyokawa, Japan


F. S. Mozer

Space Sciences Laboratory, University of California, Berkeley, California, USA


M. Andre

Swedish Institute of Space Physics, Uppsala, Sweden


Abstract

On April 13 (day 103), 2001, 0700–1400 UT, the Polar satellite experienced different plasma regimes (i.e., magnetosphere, magnetosheath, and solar wind) because of the solar wind dynamic pressure variations and its high orbital inclination near the subsolar magnetopause meridian. When Polar was in the magnetosheath, quasiperiodic spacecraft potential (SP) variations, corresponding to density variations, with a recurrence time of ∼3–10 min were observed. Using simultaneous solar wind observations, it was confirmed that the magnetosheath SP variations were inherent in the solar wind. We observed an almost one-to-one correspondence between the SP variations and the geomagnetic field perturbations at lower latitudes (L = 1.1–2.8) on the nightside. At higher latitudes (L = 2.9–6.1) on the dayside, however, the field perturbations are more complicated than the magnetosheath SP variations. This suggests that if the magnetospheric perturbations produced by the external source (solar wind/magnetosheath pressure variations) deeply penetrate into the magnetosphere, the lower-latitude data on the nightside are important to monitor the external source variations. In addition, we observed the radial electric field oscillations excited nearly simultaneously with the magnetic field enhancement, associated with a sudden increase in the solar wind dynamic pressure, when Polar was in the magnetosphere. These oscillations may be considered as transient standing Alfvén waves excited by externally applied pressure changes as reported by previous studies.

Published 27 November 2002.

Index Terms: 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2752 Magnetospheric Physics: MHD waves and instabilities; 2728 Magnetospheric Physics: Magnetosheath; 2724 Magnetospheric Physics: Magnetopause, cusp, and boundary layers.

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Citation: Kim, K.-H., C. A. Cattell, D.-H. Lee, K. Takahashi, K. Yumoto, K. Shiokawa, F. S. Mozer, and M. Andre (2002), Magnetospheric responses to sudden and quasiperiodic solar wind variations, J. Geophys. Res., 107(A11), 1406, doi:10.1029/2002JA009342.