Substorm fine structure
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Just as magnetic storms are composed of substorms, the substorms themselves seem to
be composed of smaller scale events. The concept of "multiple substorm onsets" was
even included in the substorm definition by Rostoker et al. (1980), and there is a huge
amount of studies verifying the existense of substorm finestructure. Processes with two
different time scales seem to be operating but, as yet, there is no concensus on the
5-10 min (recurrence time 10-20 min)
- Called as
- intensification (Rostoker et al., 1980)
- microsubstorm (Sergeev, 1977)
- Observed as
- steplike expansion of the auroral bulge (Vorobjev and Rezenov, 1973;
Sergeev and Yahnin, 1979; Murphree and Cogger, 1992; Nakamura et
- changes in the substorm related electrojet intensity and riometer
absorption (Sergeev, 1974; Wiens and Rostoker, 1975)
- appearance of Pi 2's (Pytte et al., 1976)
- bursts of bremsstrahlung X-rays (Lazutin et al., ICS-3)
- multiple injections of high energy particles in the near-Earth tail
- bursty bulk flows (BBF)
- separate intensifications may occur at different local time sectors; however, an
intensification itself is localized also in space (Yahnin et al., 1990)
1 min (recurrence time 1.5-3 min)
- Called as
- impulsive dissipation event (IDE; Sergeev et al., 1996)
- elementary event (Sergeev et al., 1986a,b)
- activation (Lazutin et al., manuscript 1996)
- Observed as
- auroral arc flares at the front of the auroral bulge, i.e., formation of new
arcs at the poleward boundary (Sergeev and Yahnin, 1979; Yahnin et al.,
- Pi B bursts (Bösinger et al., 1981; Bösinger and Yahnin, 1987)
- fine structure in the bursts of bremsstrahlung X-rays (Lazutin et al.,
- injection finestructure (Belian et al., 1984; Yahnin et al., 1990; Lazutin et
- flow bursts (FB)
The impulsive character of substorms has also been investigated by Murphree and
Elphinstone (1988), Williams et al. (1990), Shephard et al. (1990); Sauvaud et al.
(1987); Krimigis et al. (1979), Scholer and Roth (1987); Sergeev (1977).
- Belian, R. D., D. N. Baker, E. W. Hones, P. R. Highbie, High-energy proton
drift echoes: Multiple peak structure, J. Geophys. Res., 89, 9101-9106, 1984.
- Bösinger, T., K. Alanko, J. Kangas, H. J. Opgenoorth, and W. Baumjohann,
Correlation between Pi type magnetic micropulsations, auroras, and equivalent
current structures during two isolated substorms, J. Atmos. Terr. Phys., 43,
- Bösinger, T., and A. G. Yahnin, Pi1B type magnetic pulsations as a high time
resolution monitor of substorm development, Ann. Geophysicae, 5A, 231-238,
- Krimigis, S. and E. T. Sarris, Energetic particle bursts in the Earth's magnetotail,
in "Dynamics of the magnetosphere", ed. S.-I. Akasofu, pp. 599-618, 1979.
- Murphree, J. S. and L. L. Cogger, Observation of substorm onset, Proceedings
of the International Conference on Substorms (ISC-1), ESA SP-335,
- Murphree, J. S. and R.D. Elphinstone, Correlative studies using the VIKING
imagery, Adv. Space Res., 8, (9)9-(9)19, 1988.
- Nakamura, R., T. Oguti, T. Yamamoto, and S. Kokubun, Equatorward and
poleward expansion of the auroras during auroral substorms, J. Geophys. Res.,
98, 5743-5759, 1993.
- Pytte, T., R. L. McPherron, and S. Kokubun, The ground signatures of the
expansion phase during multiple onset substorms, Planet. Space Sci., 24,
- Rostoker, G., S.-I. Akasofu, J. C. Foster, R. A. Greenwald, Y. Kamide, K.
Kawasaki, A. T. Y. Lui, R. L. McPherron, and C. T. Russell, Magnetospheric
substorms-definition and signatures, J. Geophys. Res., 85, 1663-1668, 1980.
- Sauvaud, J. A., J. P. Treilhou, A. Saint-Marc, J. Dandouras, H. Reme, A.
Korth, G. Kremser, G. K. Parks, A. N. Zaitsev, V. Petrov, L. Lazutin, and R.
Pellinen, Large scale response of the magnetosphere to a southward turning of
the interplanetary magnetic field, J. Geophys. Res., 92, 2365-2376, 1987.
- Sergeev, V. A., On the classification of magnetospheric disturbance phenomena,
Phys. Solariterr., 4, 19-36, 1977.
- Sergeev, V. A., On the longitudinal localization of substorm active region and its
changes during the substorm, Planet. Space Sci., 22, 1341-1343, 1974.
- Sergeev, V. A., T. Bösinger, and A. T. Y. Lui, Impulsive processes in the
magnetotail during substorm expansion, J. Geophys., 60, 175-185, 1986a.
- Sergeev, V. A., R. J. Pellinen, T. Bösinger, W.Baumjohann, P. Stauning, and A.
T. Y. Lui, Spatial and temporal characteristics of impulsive structure of
magnetospheric substorms, J. Geophys., 60, 186-198, 1986b.
- Sergeev, V. A., T. I. Pulkkinen, and R. J. Pellinen, Coupled-mode model for the
magnetospheric substorms, submitted to J. Geophys. Res., 1996.
- Sergeev, V. A. and A. G. Yahnin, The features of auroral bulge expansion,
Planet. Space Sci., 27, 1429-1440, 1979.
- Shepard, G. G. and M. S. Murphree, Diagnosis of auroral dynamics using global
auroral imaging with emphasis on localized and transient features, in "Auroral
Physics", eds. C.-I. Meng, M. J. Rycroft and L. A. Frank, Cambridge Univ.
Press, Cambridge, U.K., pp. 289-298, 1990.
- Scholer, M. and D. Roth, A simulation on reconnection and small-scale
plasmoid formation, J. Geophys. Res., 92, 3223-3233, 1987.
- Vorobjev, V. G. and B. V. Rezhenov, Progressive westward displacement of
the region of the auroral substorm localization in conjunction with impulsive
variations of the magnetic field, Inst. Ass. Geomagn. Aeron., 34, 441-449,
- Wiens, R. G. and G. Rostoker, Characteristics of the development of the
westward electrojet during the expansion phase of the magnetospheric substorm,
J. Geophys. Res., 80, 2109-2128, 1975.
- Williams, P. J. S., T. S. Virdi, S. W. H. Cowley, and M. Lester, Short-lived
bursts of plasma velocity in the auroral zone. 1. Observational evidence from
radar measurements, J. Atmos. Terr. Phys., 52, 421-430, 1990.
- Yahnin, A. G., T. Bösinger, J. Kangas, and R. D. Belian, Some implications on
substorm dynamics inferred from correlations between multiple flux peaks of
drifting high-energy proton clouds and ground observations, Ann. Geophysicae,
8, 327-336, 1990.