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Winter 2004 Issue |
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Fall 2003 Aurora Events and More |
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As solar Cycle 23 progresses toward its
conclusion, both the sunspot count and the solar-flux values continue to
ratchet lower than they were a year ago. However, recent solar activity
suggests that this cycle still lives, in the process providing unexpected
excitement on the VHF ham bands. What follows is documentation of some of
the excitement that took place this past fall. On October 28, 2003, at 1048 UTC, a major solar-flare explosion was observed erupting from designated solar region 10486, at the high level of X17 (see the accompanying LASCO image photograph by NOAA). At the time, the level of the solar flare was the third largest recorded in the last two decades. The timing of the flare was such that the sunspot area from where the flare originated was in a geo-effective area pointed toward Earth. Also in contrast to previous solar flares and coronal mass ejections (CMEs), the wave action from this flare was traveling at exceptionally high speeds, in excess of 1200 km/sec. With the high speed and the geo-effective direction, impact was expected during the day of October 29. While HF operators were expecting radio blackouts and fading up to 30 MHz, VHF operators had expectations of major aurora events if the planetary K value was to reach or exceed 7. Typically, such events take about two days to travel from the sun to the Earth, but the exceptionally high speed of this particular event caused it to arrive in only one day! Impact took place at around 0900 UTC on October 29, and by 1200 UTC aurora openings were being observed on 6 meters in northern Europe. However, with the all-important Bz value (the magnetic field intensity in the all-so-important north-south direction) showing magnetic-field intensity not quite favoring southward, it took a while after impact for activity to show up in the US. By 1900 UTC aurora appeared on both the 6- and 2-meter bands in the US and Canada. The opening was fairly strong, as it reached into a number of the southern US states. It was during this time that the three-hour planetary K value reached a peak of 9.
From my QTH on Long Island I observed strong
aurora signals on 6 meters from the neighboring grid squares in
Connecticut, Massachusetts, New Jersey, Pennsylvania, and Delaware. I also
heard some signals on 2 meters from the Virginia area. There were many
visual observations of aurora in the US, although unfortunately my area
was heavily overcast, which blocked viewing. Click here to return to this month's highlights Click here to subscribe to VHF and read more about Fall 2003 Aurora Events and More _________________ © Copyright 2004, 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. |
 On October 28, 2003, at 1048 UTC, a major solar-flare explosion was observed erupting from designated solar region 10486, at the high level of X17. (LASCO image photograph by NOAA) |