| ARRL Propagation Forecast |  |
SOLAR UPDATE
Posted on aesham.com October 17, 2008
Tad "Warms in the Sun, refreshes in the breeze" Cook, K7RA, this week
reports: Finally, we are seeing Solar Cycle 24 sunspots that don't
emerge on one day, only to evaporate the next. That's right -- sunspots,
as in two or more. On Friday, October 10, sunspot 1005 emerged at high
latitude over our Sun's eastern limb; that day's sunspot number was 12.
On the following day, the sunspot number rose to 16 and a solar wind
emerging from a coronal hole caused a geomagnetic storm. The planetary A
index rose from a quiet 3 on Friday to 37, and the mid-latitude A index
was 20. The 3-hour planetary K index reached a maximum of 7 that day, a
high value for that scale. Conditions have quieted again since then. On
Sunday, Monday and Tuesday -- as the spot progressed toward the
center-north of the solar disk -- sunspot numbers were 16, 15 and 14 as
the dark spot began to fade. On Wednesday, the sunspot number faded
another point to 13, but on Thursday, October 16, sunspot 1006 emerged,
but this time in the southwest corner, about to rotate out of view. The
sunspot number for Thursday jumped to 24. Sunspot numbers for October
9-15 were 0, 12, 16, 16, 15, 14 and 13 with a mean of 12.3. The 10.7 cm
flux was 68.7, 68.9, 70.8, 70.1, 70.9, 70.4 and 70.9 with a mean of
70.1. The Estimated planetary A indices were 2, 3, 37, 13, 9, 4 and 8
with a mean of 10.9. The Estimated mid-latitude A indices were 1, 2, 20,
10, 7, 3 and 7 with a mean of 7.1.
For more information concerning radio propagation, visit the ARRL Technical Information Service Propagation page http://www.arrl.org/tis/info/propagation.html. To read this week's Solar Report in its entirety, check out the W1AW Propagation Bulletin page http://www.arrl.org/w1aw/prop/. (Reprinted from the ARRL Bulletin) |