A Challenging Solar Eruptive Event of 18 November 2003 and the Causes of the 20 November Geomagnetic Superstorm. IV. Unusual Magnetic Cloud and Overall Scenario

作者：Grechnev V V^*; Uralov A M; Chertok I M; Belov A V; Filippov B P; Slemzin V A; Jackson B V

来源：Solar Physics, 2014, 289(12): 4653-4673.

DOI：10.1007/s11207-014-0596-5

• Forbush decreases
• Geomagnetic storms
• Interplanetary coronal mass ejections
• Magnetic clouds
• Solar wind, disturbances

The geomagnetic superstorm of 20 November 2003 with Dst=-422 nT, one of the most intense in history, is not well understood. The superstorm was caused by a moderate solar eruptive event on 18 November, comprehensively studied in our preceding Papers I -aEuro parts per thousand III. The analysis has shown a number of unusual and extremely complex features, which presumably led to the formation of an isolated right-handed magnetic-field configuration. Here we analyze the interplanetary disturbance responsible for the 20 November superstorm, compare some of its properties with the extreme 28 -aEuro parts per thousand 29 October event, and reveal a compact size of the magnetic cloud (MC) and its disconnection from the Sun. Most likely, the MC had a spheromak configuration and expanded in a narrow angle of a parts per thousand currency signaEuro parts per thousand 14(a similar to). A very strong magnetic field in the MC up to 56 nT was due to the unusually weak expansion of the disconnected spheromak in an enhanced-density environment constituted by the tails of the preceding ICMEs. Additional circumstances favoring the superstorm were i) the exact impact of the spheromak on the Earth's magnetosphere and ii) the almost exact southward orientation of the magnetic field, corresponding to the original orientation in its probable source region near the solar disk center.

• 出版日期2014-12