‰ Now 18 WPM transition file follows ‰
Solar activity seems to dip back into the doldrums again, with the
average sunspot number for the past week, 72, lower than any
reporting week since Propagation Forecast Bulletin ARLP013, which
was for the week of March 21 to 27. You can go through the recent
bulletins at //www.arrl.org/ and note that two weeks ago we had
twice that number, when the average daily sunspot number was 144.
From last week, the average dropped more than 12 points from 94.3.
Average daily solar flux was down more than 10 points to 107.6. But
tracking the 3 month moving average of daily sunspot numbers, which
is based on calendar months, the three months ending May 31 had a
much higher average than the 3 months ending April 30, and in fact
more than any trailing three month average since the one ending on
January 2012. At the end of 2011 we saw a rally in solar activity,
and with the weak activity in all of 2012 some are suggesting
another double peaked solar cycle. The three month periods centered
on July through December 2011 had average sunspot numbers of 63,
79.6, 98.6, 118.8, 118.6 and 110. The first few months of 2012 were
weaker, with the 3 month averages centered on January through March
at 83.3, 73.7 and 71.2. But now the numbers are trending up. The 3
month averages centered on January through April 2013 were 73.6,
80.7, 85.2 and 106.4. If you are unfamiliar with moving averages,
using our method for the 3 month period centered on March, 2013, we
added up all the daily sunspot numbers from February 1 through April
30. The sum was 7,581. We divided by the 89 days in those three
months, and got approximately 85.2. On June 3 NASA updated their
forecast for the peak of the current solar cycle, available at
//solarscience.msfc.nasa.gov/predict.shtml. This differs from a
month earlier, when on May 1 they predicted a cycle maximum in Fall
2013 with a smoothed international sunspot number of 66. Now they
predict a peak at 67 in Summer 2013. The planetary A index was 17
on June 6, with increasing K index values from 2 to 3 to 4. Now
early on June 7 we see planetary K index of 5 and 6, which is the
equivalent to an A index reading of 64. Now after 1200 UTC it
dropped to 56. Sunspot numbers were 71, 58, 60, 76, 99, 59, and 81,
with a mean of 72. 10.7 cm flux was 104.1, 101.8, 105.8, 110.9,
111.8, 109.9, and 108.8, with a mean of 107.6. Estimated planetary
A indices were 3, 9, 49, 19, 10, 10, and 6, with a mean of 15.1.
Estimated mid latitude A indices were 2, 7, 41, 16, 9, 10, and 9,
with a mean of 13.4.
‰ End of 18 WPM transition file ‰