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The K7RA Solar Update


A dramatic surge in solar activity is underway, with a level of sunspot numbers and solar flux not seen since 2005-2006. Tuesday’s sunspot number of 100 has not been equaled or exceeded since April 6, 2006 when it was 105. On Wednesday, the solar flux was 114.1, and the last time it was that high or higher was September 15, 2005 at 119.4. The average daily sunspot numbers rose this week by more than 25 points to 69.9, and the average daily solar flux was up 20 points to 103.5.

Sunspot numbers for February 10-16 were 38, 54, 63, 84, 90, 100 and 60, with a mean of 69.9. The 10.7 cm flux was 91.4, 91.2, 95.6, 106.8, 112.6, 112.8 and 114.1, with a mean of 103.5. The estimated planetary A indices were 3, 4, 4, 2, 10, 5 and 2, with a mean of 4.3. The estimated mid-latitude A indices were 4, 3, 2, 1, 6, 4 and 1, with a mean of 3.

NOAA/USAF predicts solar flux at 110 on February 18-19, 105 on February 20, 100 on February 21 and 105 on February 22-24. Planetary A index is predicted at 25 and 12 on February 18-19, and 5 on February 20-28, then rising to 7, 10, 10 and 7 on March 1-4. Geophysical Institute Prague predicts active conditions on February 18, unsettled to active February 19, unsettled February 20, quiet to unsettled February 21 and quiet conditions February 22-24.

This weekend is the ARRL DX CW Contest, and Bob Marston, K6TW notes that a geomagnetic storm is predicted for Friday, just before the start of the contest. This is due to two coronal mass ejections, one on February 13 at 1735, and the other on February 15 at 0156. A CME hit the Earth’s magnetic field at 0100 today, February 18, but it was not as strong as expected. It is possible we may be spared major geo-storms; however, there is a new alert from Solar Storm Watch of an expected CME direct hit at 0900 on February 18. The planetary K index on February 18 at 0300, 0600 and 0900 was 3, 4 and 5.

Most of the activity this week has been from large sunspot group 1158, which will soon rotate out of view over the Sun’s western limb. More centrally positioned is sunspot 1161, and there seems to be a new sunspot emerging above it. It is probably significant that USAF/NOAA revised the solar flux estimate upward for the near term between Wednesday’s and Thursday’s prediction.

K6TW introduced us to a resource for updates on solar activity, and specifically a Twitter resource that you can read without a Twitter account.

Fred Honnold, KH7Y, of Ocean View, Hawaii (on the southern part of the big island of Hawaii) has a report of some 10 meter longpath to Europe propagation on February 14: “I wanted to let you know about some excellent long path QSO last night from 0923 till 1055. The bands were still alive but it was 1 AM here and I just quit. Signal levels on 15 meters from the KW stations were S8 or so on 12 meters. The signals were still strong, so after working about 100 stations on 12 meters, I moved to 10 meters. I worked many European stations with signals S1 to S5 the best signals was from EA1DR S9+ and S57S very loud.”

You can see the spots by going to DX Sherlock. Just select 28 MHz, February 14 from 1000 to 1059, containing the call sign KH7Y. Set maximum number of returned QSOs at 100, then Submit Query.

An article on the ARRL website about sunspot 1158 and this week’s activity mentions that “According to NASA, the Sun will reach its next maximum this year, give or take one year.” I don’t think this is true, as the latest prediction for the next solar maximum is in 2013. If you check a recent Preliminary Report and Forecast, look on page 10 and note that the highest smoothed sunspot number in the near future is 90, predicted for February through July 2013.

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 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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