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A satellite magnetometer observation of dusk-to-dawn current in the midnight magnetosphere at low-latitude Pi2 onset


A multiple Pi2 event was observed in the midnight sector at the low-latitude ground magnetometer station. Meanwhile, particle fluxes in the midnight sector were measured during the multiple Pi2 event by the AMPTE/CCE spacecrafts in the L range from 4.8 to 5.8 and by geosynchronous satellite, S/C1984-129, at the dawn sector. We present an examination of the magnetic field changes and the associated particle behavior during the multiple Pi2 event. We argue that the temporal intensification of the dusk-to-dawn currents near the geosynchronous altitudes may trigger the Pi2 pulsations. The plasmas injected in the inner magnetosphere are possible candidate for driving the dusk-to-dawn currents.


  • Akasofu, S.-I., The development of auroral substorm, Planet. Space Sci., 12, 273, 1964.

    Article  Google Scholar 

  • Allan, W., F. W. Menk, B. J. Fraser, Y. Li, and S. P. White, Are low-latitude Pi 2 pulsations cavity/waveguide modes?, Geophys. Res. Lett., 23, 765, 1996.

    Article  Google Scholar 

  • Baker, D. N., et al., Neutral line model of substorms: Past results and present view, J. Geophys. Res., 101, 12975, 1996.

    Article  Google Scholar 

  • Birn, J., et al., MHD simulations of magnetotail dynamics, J. Geophys. Res., 101, 12939, 1996.

    Article  Google Scholar 

  • Friedel, R. H., et al., Substorm onsets observed by CRRES: Determination of energetic particle source regions, J. Geophys. Res., 101, 13137, 1996.

    Article  Google Scholar 

  • Fujita, S., M. Itonaga, and H. Nakata, Relation between the Pi2 pulsations and the localized impulsive current associated with the current disruption in the magnetosphere, Earth Planets Space, 52, 267–281, 2000.

    Article  Google Scholar 

  • Fujita, S., H. Nakata, M. Itonaga, A. Yoshikawa, and T. Mizuta, A numerical simulation of the Pi2 pulsations associated with the substorm current wedge, J. Geophys. Res., 107, SMP2–1–2–15, 2002.

    Google Scholar 

  • Hsu, T. S. and R. L. McPherron, Occurrence frequency of substorm field and plasma signatures observed near-earth by ISEE-1/2, in Proc. ICS-3, edited by E. J. Rolfe and B. Kaldeic, 1996.

  • McIlwain, C. E., Substorm injection boundaries, in Magnetospheric Physics, edited by B. M. McCormac, p. 143, D. Reidel, Hingham, Mass., 1974.

    Chapter  Google Scholar 

  • Moore, T. E., et al., Propagating substorm injection fronts, J. Geophys. Res., 86, 6713, 1981.

    Article  Google Scholar 

  • Reeves, G. D., T. A. Fritz, T. E. Cayton, and R. D. Belian, Multi-satellite measurements of the substorm injection region, Geophys. Res. Lett., 17, 2015, 1990.

    Article  Google Scholar 

  • Saka, O., H. Akaki, O. Watanabe, and D. N. Baker, Ground-satellite correlation of low-latitude Pi2 pulsations: A quasi-periodic field line oscillation in the magnetosphere, J. Geophys. Res., 101, 15433, 1996a.

    Article  Google Scholar 

  • Saka, O., O. Watanabe, and D. N. Baker, A possible driving source for transient field line oscillations in the postmidnight sector at geosynchronous altitudes, J. Geophys. Res., 101, 24719, 1996b.

    Article  Google Scholar 

  • Saka, O., et al., An initial response of magnetic fields at geosynchronous orbit to Pi 2 onset as observed from the dip-equator, Ann. Geophysicae, 16, 542, 1998.

    Article  Google Scholar 

  • Shiokawa, K., W. Baumjohann, and G. Haerendel, Braking of high-speed flows in the near-Earth tail, Geophys. Res. Lett., 24, 1179, 1997.

    Article  Google Scholar 

  • Yeoman, T. K., et al., A comparison of midlatitude Pi 2 pulsations and geostationary orbit particle injections as substorm indicators, J. Geophys. Res., 99, 4085, 1994.

    Article  Google Scholar 

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Correspondence to O. Saka.

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Saka, O., Akaki, H. & Baker, D.N. A satellite magnetometer observation of dusk-to-dawn current in the midnight magnetosphere at low-latitude Pi2 onset. Earth Planet Sp 54, e1–e4 (2002).

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