[en] The FUV imagers on board the IMAGE satellite provide multispectral snapshots of the polar region every 2 min. The combination of the Wide-Angle Imaging Camera (WIC) with SI12 (Doppler shifted Lyman-alpha) and SI13 (135.6 nm) spectral imagers is used to discriminate between the electron and the proton aurora. We describe a statistical study of the location of 78 substorms observed close to the 2000-2001 winter solstice. The latitudinal distribution of the onsets observed with WIC is asymmetric with a median at 65.6° MLAT and a full width at half maximum (FWHM) of 3.5°. Their local time distribution is concentrated between 2000 and 0200 MLT with a median at 23.4 +/- 0.3 hours MLT and a FWHM of 1.8 hours. No statistically significant difference is found in the spatial distribution of the proton and electron onsets. All onsets take place within a region of preexisting proton precipitation, indicating that substorm initiation occurs in regions of stretched but dipole-like field lines that cross the equatorial plane close to the Earth. Latitudes of substorm onsets are located at a variable distance from the poleward FUV auroral boundary but remain at a nearly constant distance from the equatorward limit of both proton and electron auroral ovals. The magnetic latitudes of the onsets are correlated with some of the solar wind plasma properties measured by the ACE satellite prior to the substorm breakup. In particular, a clear anticorrelation is found between the onset MLAT and the 1-hour averaged solar wind dynamic pressure. A decrease of the onset latitude is also observed for larger B intensity values. No dependence of the onset MLT on the solar wind speed is observed, in contrast to the relationship expected from the thermal catastrophe model for substorm initiation. Our results are in agreement with models locating the initial instability in the near magnetosphere such as the near-Earth current disruption models.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Gérard, Jean-Claude ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Hubert, Benoît ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Grard, Aline ; Université de Liège - ULiège > Aquapôle
Meurant, M.
Mende, S. B.
Language :
English
Title :
Solar wind control of auroral substorm onset locations observed with the IMAGE-FUV imagers
Publication date :
01 March 2004
Journal title :
Journal of Geophysical Research. Space Physics
ISSN :
2169-9380
eISSN :
2169-9402
Publisher :
American Geophysical Union (AGU), Washington, United States - District of Columbia
Akasofu, S. I. (1964), The development of the auroral substorms, Planet. Space Sci., 12, 273.
Baker, J. B., C. R. Clauer, A. J. Ridley, V. O. Papitashvili, M. J. Brittnacher, and P. T. Newell (2000), The nightside poleward boundary of the auroral oval as seen by the MSP and the Ultraviolet Imager, J. Geophys. Res., 105, 21,267.
Baker, D. N., et al. (2002), Timing of magnetic reconnection initiation during a global magnetospheric substorm onset, Geophys. Res. Lett., 29(24), 2190, doi:10.1029/2002GL015539.
Brittnacher, M. J., M. Fillingim, G. Parks, G. Germany, and J. Spann (1999), Polar cap area and boundary motion during substorms, J. Geophys. Res., 104, 12,251.
Burch, J. L., et al. (2001), Views of Earth's magnetosphere with the IMAGE satellite, Science, 291, 619.
Craven, J. D., and L. A. Frank (1991), Diagnosis of auroral dynamics using global auroral imaging with emphasis on large-scale evolutions, in Auroral Physics, edited by C.-I. Meng, M. J. Rycroft, and L. A. Frank, p. 273, Cambridge Univ. Press, New York.
Donovan, E. F., B. J. Jackel, I. Voronkov, T. Sotirelis, F. Creutzberg, and N. A. Nicholson (2003), Ground-based optical determination of the b2i boundary: A basis for an optical MT-index, J. Geophys. Res., 108(A3), 1115, doi:10.1029/2001JA009198.
Dubyagin, S. V., V. A. Sergeev, C. W. Carlson, S. R. Marple, T. I. Pulkkinen, and A. G. Yahnin (2003), Evidence of near-Earth breakup location, Geophys. Res. Lett., 30(6), 1282, doi:10.1029/2002GL016569.
Frank, L. A., and J. D. Craven (1988), Imaging results from Dynamics Explorer I, Rev. Geophys., 26, 249.
Frank, L. A., and J. B. Sigwarth (2000), Findings concerning the positions of substorm onsets with auroral images from the Polar spacecraft, J. Geophys. Res., 105, 12,747.
Frey, H. U., T. J. Immel, S. B. Mende, J.-C. Gérard, B. Hubert, S. Habraken, J. Spann, and G. R. Gladstone (2003), Summary of quantitative interpretation of IMAGE far ultraviolet auroral data, Space ScL Rev., 109, 255.
Galperin, Y. I., and Y. I. Feldstein (1991), Auroral luminosity and its relationship to magnetospheric plasma domains, in Auroral Physics, edited by C.-I. Meng, M. J. Rycroft, and L. A. Frank, p. 207, Cambridge Univ. Press, New York.
Gérard, J. C., B. Hubert, D. V. Bisikalo, V. I. Shematovich, H. U. Frey, S. B. Mende, G. R. Gladstone, and C. W. Carlson (2001), Observation of the proton aurora with IMAGE-FUV and simultaneous ion flux in situ measurements, J. Geophys. Res., 106, 28,939.
Gladstone, R. G., et al. (2000), Stellar calibration of the WIC and SI imagers and the GEO photometer on IMAGE/FUV, Eos Trans. AGU, 81(48), Fall Meet. Suppl., Abstract SM72A-06.
Goertz, C. K., and R. A. Smith (1989), The thermal catastrophe model of substorms, J. Geophys. Res., 94, 6581.
Henderson, M. G., and J. S. Murphree (1995), Comparison of Viking onset locations with the predictions of the thermal catastrophe model, J. Geophys. Res., 100, 21,857.
Holworth, R. H., and C.-I. Meng (1984), Auroral boundary variations and the interplanetary magnetic field, Planet. Space. Sci., 32, 25.
Hubert, B., J. C. Gérard, D. S. Evans, M. Meurant, S. B. Mende, H. U. Frey, and T. J. Immel (2002), Total electron and proton energy input during auroral substorm: Remote sensing with IMAGE-FUV, J. Geophys. Res., 107(A8), 1183, doi:10.1029/2001JA009229.
Kauristie, K., J. Weygand, T. I. Pulkkinen, J. S. Murphree, and P. T. Newell (1999), Size of the auroral oval: UV ovals and precipitation boundaries compared, J. Geophys. Res., 104, 2321.
Liou, K., P. T. Newell, C.-I. Meng, M. Brittnacher, and G. Parks (1998), Characteristics of the solar wind controlled auroral emissions, J. Geophys. Res., 103, 17,543.
Liou, K., C.-I. Meng, T. Y. Lui, P. T. Newell, M. Brittnacher, G. Parks, G. D. Reeves, R. R. Anderson, and K. Yumoto (1999), On relative timing in substorm onset signatures, J. Geophys Res., 104, 22,807.
Liou, K., P. T. Newell, D. G. Sibeck, C. I. Meng, M. Brittnacher, and G. Parks (2001), Observation of IMF and seasonal effects in the location of auroral substorms, J. Geophys. Res., 106, 5799.
Lopez, R. E., A. T. Y. Lui, D. G. Sibeck, K. Takahsahi, R. W. Mclntire, L. J. Zanetti, and S. M. Krimigis (1989), On the relationship between the energetic particle flux morphology and the change in the magnetic field magnitude during substorms, J. Geophys. Res., 94, 17,105.
Lui, A. T. Y. (2001), Current controversies in magnetospheric physics, Rev. Geophys., 39, 535.
Lyons, L. R., I. O. Voronkov, E. F. Donovan, and E. Zesta (2002), Relation of substorm breakup arc to other growth-phase auroral arcs, J. Geophys. Res., 107(A11), 1390, doi:10.1029/2002JA009317.
McPherron, R. L., C. T. Russell, and M. P. Aubry (1973), Satellite studies of magnetospheric substorms on August 15, 1968: 9. Phenomenological model for substorms, J. Geophys. Res., 75, 3131.
Mauk, B. H., and C. E. McIlwain (1974), Correlation of Kp with the substorm-injected plasma, J. Geophys. Res., 79, 3193.
Mende, S. B., et al. (2000), Far ultraviolet imaging from the IMAGE spacecraft: 1. System design, Space Sci. Rev., 91, 243.
Mende, S. B., C. W. Carlson, H. U. Frey, L. M. Peticolas, and N. Østgaard (2003), FAST and IMAGE-FUV observations of a substorm onset, J. Geophys. Res., 108(A9), 1344, doi:10.1029/2002JA009787.
Meng, C. I., B. Tsurutani, K. Kawasaki, and S. I. Akasofu (1973), Cross-correlation analysis of the AE index and the interplanetary magnetic field Bz component, J. Geophys. Res., 78, 617.
Murphree, J. S., R. D. Elphinstone, M. G. Henderson, L. L. Cogger, and D. J. Hearn (1993), Interpretation of optical substorm onset observations, J. Atmos. Terr. Phys., 55, 1159.
Newell, P. T., Y. I. Feldstein, Y. I. Galperin, and C. I. Meng (1996), Morphology of nightside precipitation, J. Geophys. Res., 101, 10,737.
Richmond, A. D. (1995), Ionospheric electromagnetics using magnetic apex co-ordinates, J. Geomagn. Geoelectr., 47, 191.
Samson, J. C., L. Lyons, P. T. Newell, and F. Creutzberg (1992), Proton aurora and substorm intensifications, Geophys. Res. Lett., 19, 2167.
Shiokawa, K., W. Baumjohann, and G. Haeredel (1997), Breaking of high speed flows in the near-Earth tail, Geophys. Res. Lett., 24, 1179.
Tsyganenko, N. A. (1987), Global quantitative model of the geomagnetic field in the cislunar magnetosphere for different disturbance levels, Planet. Space Sci., 95, 1347.
Vasyliunas, V. M., J. R. Kan, G. L. Siscoe, and S. I. Akasofu (1982), Scaling relations governing magnetospheric energy transfer, Planet. Space Sci., 30, 359.
Voronkov, I. O., E. F. Donovan, P. Dobias, J. C. Samson, and L. R. Lyons (2002), Near-Earth breakup in substorms: Empirical and model constraints, in Proceedings of the Sixth International Conference on Substorms, edited by R. M. Winglee, p. 270, Univ. of Wash., Seattle, Wash.
Voronkov, I. O., E. F. Donovan, and J. C. Samson (2003), Observations of the phases of the substorm, J. Geophys. Res., 108(A2), 1073, doi:10.1029/2002JA009314.