Winter 2005 Issue

PROPAGATION

More on Sporadic-E

 By Tomas Hood, NW7US/AAAØWA

During the beginning of November 2004, a series of solar-flare eruptions occurred originating from a large and moderately complex sunspot group, NOAA Region 696. Solar-flare activity starting with the November 5th long-duration M-class flare resulted in a series of Earth-directed coronal mass ejections (CMEs) that impacted Earth’s geomagnetic field with severe (G4) geomagnetic storms. On November 7th a large flare eruption on the Sun triggered a moderate to strong solar-radiation storm. The CME activity produced periods of strong geomagnetic storms starting on November 7th, but peaking on November 8th and 10th.

Solar-radiation storms cause an increase in proton bombardment of the Earth. One result of November’s geomagnetic storms and proton events was the extraordinary display of the aurora both in the Northern and Southern Hemispheres. Observers of the visual light show reported seeing the aurora as far south as Alabama in the Northern Hemisphere and as far north as New Zealand in the Southern Hemisphere.

The plots shown in figures 1 and 2 show a comparison of normal solar activity in October 2004 versus the activity during the geomagnetic storm during November. The difference is dramatic. In particular, note the large increase in highest-level (green) proton flux on November 10th. The increase in these particles rarely rises above the 0.1 (first) level on this plot.
 

Click here to return to Winter 2005 highlights

Click here to subscribe to VHF

_________________

© Copyright 2005, CQ Communications, Inc. All rights reserved. This material may not be reproduced or republished, including posting to a website, in part or in whole, by any means, without the express written permission of the publisher, CQ Communications, Inc. Hyperlinks to this page are permitted.

Figure 6. The solar-storm action continued during November 9th and 10th due to the solar activity seen in these LASCO C2 images. (NASA/SOHO image)