The K7RA Solar Update

SEATTLE, WA, Mar 24, 2006--There were no zero-sunspot days
over the past week. In fact, the average daily sunspot number was
a little more than double the previous week's numbers, rising by
more than 17 points to 33.4. This was a nice little uptick toward the
solar cycle minimum, coming with the start of spring in the Northern
Hemisphere. Unfortunately for HF operators, the average
geomagnetic numbers doubled as well. This and the associated
aurora were triggered by a solar wind stream that hit Earth starting
last Saturday, March 18. Maximal effects were felt the following
day, when the College A index--measured less than two degrees
latitude south of the Arctic Circle--rose to 51 on March 19.
Saturday's College A index was 39, but on Friday, March 17 it was
only 2--very quiet. The Planetary A index over those same days
was 3, 26 and 37, and the mid-latitude A index was 2, 15 and 24.

This weekend is the CQ World Wide WPX Contest (SSB), and
there shouldn't be any nasty surprises regarding propagation.
Predicted planetary A index for the next five days, March 24-28, is
12, 12, 10, 7 and 5.

For more information concerning 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 March 16 through 22 were 22, 24, 27, 40, 33, 39 and 49, with
a mean of
33.4. The 10.7 cm flux was 72.4, 72, 72.4, 75.2, 76.9, 76.7, and 75.9, with a
mean of 74.5.
Estimated planetary A indices were 6, 3, 26, 37, 22, 13 and 10, with a mean of
16.7. Estimated
mid-latitude A indices were 4, 2, 15, 24, 14, 8 and 9, with a mean of 10.9.
(K7RA, ARRL)

dxAce
Michigan
USA