NASA IMAGE Satellite has Close-up View of Sudden Storm Commencement.

The first indication of the arrival of the massive coronal mass ejection (CME) associated with the October 28 X17-class solar flare was detected just after 6 UT on October 29, hardly amounting to a 19 hour transit time of the CME. The rapid, near instantaneous compression of the magnetopause was detected by magnetometers on the GOES satellites, and in particle fluxes measured at geosynchonous orbit by the MPA and SOPA detectors onboard the Los Alamos geosynchronous satellites. Judging from these data, and the sudden drop in Dst at this time, we can call this a sudden storm commencement. Multiple sudden storm commencements are hallmarks of the largest magnetic storms, sometimes coined "Super Storms" [Bell et al., 1997].

The NASA-IMAGE satellite was just over Earth's South Pole when the CME hit, and obtained a set of Far-Ultraviolet images which showed the result of the compression. The raw images are shown below (click for a larger view).

WIC Images

The images show a relatively quiet aurora (of N2 LBH emissions) that, at 0613 UT, undergoes a simultaneous brightening at all local times, and a subsequent rapid expansion of the aurora into the previously empty polar cap . The slight blurring in some images is probably due to the rapid motion of auroral forms as the area of strong precipitation expands into the polar cap during the 10 second integration time for these images. This instantaneous global brightening and rapid expansion is a relatively unusual development that can occur when a large shock in the solar wind impinges upon the magnetosphere. [Chua et al., 2001, and references therin] In each of these images the sun is at about 10 o'clock, and each image is scaled to the brightest features in the aurora. A movie of this event shows a longer series of images, where each is scaled similarly and some of the dayglow is removed.

An hour later, the satellite has proceeded to higher altitudes and the auroral proton precipitation pattern can be seen, using the  SI-12 proton imager. From these images, it is clear that the interplanetary magnetic field is highly variable, and that the solar wind is very dense. This is because the bright emissions near noon (leftmost portion of auroral oval), which are known to indicate the footpoint of the magnetospheric cusp, are extremely bright and vary rapidly in mean location. The emissions exceed the top range of the color bar at 120 counts, reminscent of the massive proton aurora observed after the Bastille Day, 2000 solar flare. The variation in location is mainly in latitude, with IMF By also influencing the local time of the emissions. Two examples below are indicative of these solar wind properties.

IMF Southward Proton Aurora
IMF Northward Proton Aurora
Bz-south proton aurora
Bz-north proton aurora

A movie of this event shows the rapidly moving cusp signature, which reflects the rapidly varying interplanetary field orientation. The IMF dependence of the proton cusp signature has been described at length recently in several papers by Frey et al. [2002, 2003].

movie of this event This is just the first indication of activity and this storm is a continuing event, now with (a possibly unprecedented) 2 successive dips of DST below -300 nT. Stay tuned for more great auroral images!

GOES X-ray and Magnetometer plots : NOAA Space Environment Center (SEC).
LANL MPA and SOPA quicklook data : Los Alamos National Laboratory, NIS Division,

Important References:

Super storms
Bell, J. T.; Gussenhoven, M. S.; Mullen, E. G.
Journal of Geophysical Research, Volume 102, Issue A7, July 1, 1997, pp.14189-14198

Energy characteristics of auroral electron precipitation: A comparison of substorms and pressure pulse related auroral activity
Chua, D.; Parks, G.; Brittnacher, M.; Peria, W.; Germany, G.; Spann, J.; Carlson, C.
Journal of Geophysical Research, Volume 106, Issue A4, April 1, 2001, pp.5945-5956

Proton aurora in the cusp during southward IMF
Frey, H. U.; Mende, S. B.; Fuselier, S. A.; Immel, T. J.; Østgaard, N.
Journal of Geophysical Research Space Physics, Volume 108, Issue A7, pp. SMP 6-1, CiteID 1277, DOI 10.1029/2003JA009861

Proton aurora in the cusp
Frey, H. U.; Mende, S. B.; Immel, T. J.; Fuselier, S. A.; Claflin, E. S.; Gérard, J.-C.; Hubert, B.
Journal of Geophysical Research (Space Physics), Volume 107, Issue A7, pp. SMP 2-1, CiteID 1091, DOI 10.1029/2001JA900161

last edited by Thomas Immel (immel at ssl dot berkeley dot edu) on October 30, 2003.