The K7RA Solar Update
Tad
Cook, K7RA, Seattle, reports: The Sun just completed an extended period
(16 days) of zero sunspots. None were visible on March 4, one showed up
on March 5, and then there were none from March 6 through March 20.
Finally, one sunspot group appeared on March 21-22, yielding a sunspot
number of 12 for both days. Some explanation: Every group of sunspots
counts as 10 points, and every sunspot within those groups counts for 1
point, so the minimum non-zero sunspot number is 11.
The
average daily sunspot number over the March 16-22 reporting week was
3.4, compared to zero during the previous 7 days. Average daily solar
flux bumped up from 70.3 to 71.2.
The average daily planetary A index increased from 8.1 to 10, and the average mid-latitude A index rose from 6.4 to 7.1.
The
mid-latitude A index is measured at one magnetometer at Wallops Island,
Virginia, while the planetary A index is calculated based on a number
of magnetic observatories, most in the Northern Hemisphere.
Predicted
solar flux is 74 on March 23; 75 on March 24-25; 76 on March 26-29; 72
on March 30-April 4; 71 on April 5; 70 on April 6-17; 71 on April 18,
and 72 for April 19-May 1.
Predicted planetary A
index is 20 and 14 on March 23-24; 8 on March 25-26; 20, 38, 24, 20, and
18 on March 27-31; 15, 20, and 15 on April 1-3; 12 on April 4-5; 10 on
April 6; 5 on April 7-16; 8, 12, 20, 8, 5, and 8 on April 17-22, and 8,
35, 30, 20, 18, 15, 20, and 15 on April 23-30.
For more information concerning radio propagation, see the ARRL Technical Information Service. For an explanation of numbers used in this bulletin, see "What the Numbers Mean, and Propagation Predictions -- a brief introduction to propagation and the major factors affecting it."
An archive of past propagation bulletins is available on the ARRL website, and Carl Luetzelschwab, K9LA, offers additional propagation information and tutorials on his website.
Sunspot
numbers for March 16 through 22, 2017 were 0, 0, 0, 0, 0, 12, and 12,
with a mean of 3.4. The 10.7-centimeter flux was 70.5, 70.5, 70.2, 71.2,
72.7, 71, and 72.5, with a mean of 71.2. Estimated planetary A indices
were 6, 4, 2, 2, 3, 26, and 27, with a mean of 10. Estimated
mid-latitude A indices were 5, 3, 1, 2, 2, 18, and 19, with a mean of
7.1.
