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The K7RA Solar Update


The average daily sunspot numbers were up over the past week, 12.3 points -- or about 13 percent -- to 107.6. Likewise, the average daily solar flux rose 14.2 points -- or 11 percent -- to 143.1. Sunspot numbers for December 22-28 were 105, 123, 101, 66, 110, 126 and 122, with a mean of 107.6. The 10.7 cm flux was 145.8, 138.2, 142.8, 144.3, 145.6, 140.3 and 144.8, with a mean of 143.1. The estimated planetary A indices were 2, 1, 1, 1, 1, 0 and 2, with a mean of 1.1. The estimated mid-latitude A indices were 4, 2, 2, 3, 2, 2, and 4, with a mean of 2.7.

The predicted solar flux for the near term is about the same, 145 on December 30-January 6. From January 7-8, the predicted flux values are 130, then 135 on January 9-12, and then 140 on January 13-15. The solar flux is expected to peak around 150 on January 24, then go to a minimum of 130 on January 31-February 4. The predicted planetary A index is 8, 5, 10, 10 and 8 on December 30-January 3, then 5 on January 4-27, and then 8 on January 28-29. Geophysical Institute Prague predicts unsettled conditions December 30, quiet to unsettled December 31 to January 1 and quiet conditions January 2-5.

Conditions should be good for the ARRL Straight Key Night, the 24 hours in which we celebrate our communications heritage with CW and manual keys.

It’s funny how these predictions sometimes turn out. You can subscribe to geomagnetic warnings from the Ionospheric Prediction Service -- part of the Australian Department of Industry, Science and Resources. They issued a geomagnetic disturbance warning at 0338 on December 22, predicting quiet conditions prior to possible shock arrival on December 24, active conditions possible December 25,and unsettled to active conditions December 26.

A coronal mass ejection appeared to be in a geoeffective position, meaning it was aimed at Earth. But apparently it missed us, and the readings from magnetometers bear this out. Check the A and K index recordings and note all quiet around those dates. The high latitude college A index (and the K index it is based on) from Fairbanks, Alaska was a flat 0 from December 23-28, and this is at a latitude that is most affected by high solar activity.

You can subscribe to the IPS warnings. Similar products are also available from NOAA SWPC.

This article from Great Britain’s Daily Mail seems to warn of mayhem from a “massive solar storm.” But in the body of the text, we see that NOAA’s Space Weather Prediction Center wrote: “Category G1 (Minor) geomagnetic storms are expected 28 and 29 December due to multiple coronal mass ejection arrivals. R1 (Minor) radio blackouts are expected until 31 December.”

And here is a worse example, although I do not know if Romania Business Insider is a real newspaper, but they do list a byline for a reporter with an e-mail address. The article seems to recycle six-year-old news releases. Note that the quote about “30 to 50 percent stronger” seems to be from this news release from 70 months back. Of course, the latest predictions say 2013 instead of 2012, weaker and not stronger, but I have no idea where that prediction for activity as big as Solar Cycle 19 in the late 1950s came from. The latest cycle forecast was issued a couple of weeks back.

According to Robert Steenburgh, KA8JBY, of Longmont, Colorado, you can monitor solar flare impacts on the ionosphere. Since there hasn’t been much activity of late, you can check out past conditions in the archive. An experimental auroral forecast is here.

We don’t know the precise daily average of sunspot numbers for the calendar year, but with 99.5 percent of the data available, our figures are pretty close. Of course, a calendar year is an arbitrary period for averaging sunspot numbers, but the yearly averages of daily sunspot numbers for 2003-2011 are 109.2, 68.6, 48.9, 26.1, 12.8, 4.7, 5.1, 25.5 and 80.1. This is a good trend, and note that the average daily sunspot numbers for the past 100 days (again, another arbitrary period) is 117.1, substantially higher than all of the past year, and higher than all of 2003.

If you want to look at average sunspot numbers for every month since January 1749 (that’s 13,713 weeks) check this out. Note these are the lower International Sunspot Numbers, not the NOAA values we give here. Also note that the current Gregorian calendar was not adopted in the United States until three years and eight months after the beginning of this record. Back then, it was all Julian calendars.

Did you know that in 2011 we had only two days with 0 sunspots? In 2010 it was 51 days, and 2009 had 260 spotless days

All times listed are UTC, unless otherwise noted.

Amateur solar observer Tad Cook, K7RA, of 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 each Thursday in The ARRL Letter. You can find a guide to articles and programs concerning propagation here. Check here and here for a detailed explanation of the numbers used in this bulletin. An archive of past propagation bulletins can be found here. You can find monthly propagation charts between four USA regions and 12 overseas locations here. Readers may contact the author via e-mail.



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