The K7RA Solar Update
SEATTLE, WA, Aug 19, 2005--Not much solar activity
occurred over the past week. A few days ago Earth entered a solar wind stream
which raised geomagnetic activity, but not to the level of a storm.
Sunspot numbers and solar flux are expected to remain low
but rise moderately again around August 26 and through the end of the month. Geomagnetic
conditions should stay mild, with unsettled conditions returning around August
23-26.
Frank Donovan, W3LPL, of Glenwood, Maryland sent in some
interesting Web links (1) (2) regarding 6 meters and sporadic
E propagation. On the k1six.com link, the dates may be a bit confusing, because
the title says the graph covers the period from 1995 to present, but the dates
along the X axis run from early May to the present. This graph shows cumulative
activity during May through August over the past decade, so the data isn't just
from this year. It illustrates when sporadic E propagation across the Atlantic is the most common--in late June and early July.
We get reports of TV and FM DX during sporadic E season
and sometimes mention them in the bulletin. Doug Allen, W0AH, of Woodland Park, Colorado, wrote to say that receiving FM and TV stations from more than 1000
miles away via sporadic E is fairly common in the summer. He has personally
logged more than 3000 FM broadcast stations via sporadic E, and a few hundred
of those were 1450-1500 miles distant.
For more information concerning radio propagation and an
explanation of the numbers used in this bulletin see the ARRL Technical
Information Service Propagation
page. An archive of past bulletins is on
the ARRL Web site.
Sunspot numbers for August 11 through 17 were 35, 47, 33,
34, 49, 48 and 42, with a mean of 41.1. The 10.7 cm flux was 75.9, 76.2, 75.4,
74.8, 75.8, 75.8 and 77, with a mean of 75.8. Estimated planetary A indices
were 6, 6, 16, 10, 8, 19 and 18, with a mean of 11.9. Estimated mid-latitude A
indices were 2, 3, 14, 6, 6, 12 and 11, with a mean of 7.7.
Amateur
solar observer Tad Cook, K7RA, Seattle, Washington, provides this weekly report
on solar conditions and propagation. This report also is available via W1AW
every Friday, and an abbreviated version appears in The ARRL Letter. Readers may contact
the author via e-mail.
Page last modified: 10:39 AM, 19 Aug 2005 ET
Page author: awextra@arrl.org
Copyright © 2005, American Radio Relay League, Inc. All Rights Reserved.
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