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The K7RA Solar Update

03/17/2017

There haven’t been sunspots since March 3, other than March 5, when one sunspot appeared for only one day. Also, solar flux values have recently dipped below 70, for the first time since the other side of this solar cycle.

Solar flux appears at 70 over the past week: ftp://ftp.swpc.noaa.gov/pub/indices/DSD.txt

But this is an approximation. Resolved to 0.10, you can see that it is dipping lower: http://www.spaceweather.ca/solarflux/sx-5-flux-en.php. You want to look at the Observed Flux column.

Average daily sunspot number dropped from 14.1 to zero. Average daily solar flux went from 74.3 to 70.3.

Average daily planetary A Index quieted from 20.9 to 8.1, while average mid-latitude A index went from 15 to 6.4.

Predicted solar flux is 71 on March 17, 72 on March 18-20, 73 on March 21, 74 on March 22-23, 76 on March 24-25, 74 on March 26-29, 72 on March 30 through April 3, and 70 on April 4-9.

Predicted planetary A index is 10 and 8 on March 17-18, 5 on March 19-20, then 8, 10, 8 and 8 on March 21-24, 5 on March 25-27, then 35, 30, 20, 18, 15, 20 and 15 on March 28 through April 3, 12 on April 4-5, 10 and 5 on April 6-7, then 8 on April 8-13, 12 and 10 on April 14-15, 5 on April 16-17, then 10, 15 and 8 on April 18-20, and 5 on April 21-23.


F. K. Janda, OK1HH of the Czech Propagation Interest Group sent us this geomagnetic activity forecast for the period March 17-April 12, 2017.

"Geomagnetic field will be:
Quiet on March 26, April 6-7, 9-10
Mostly quiet on March 21, April 5, 11
Quiet to unsettled March 22, (27,) April 1-2, 4
Quiet to active on March 17-20, (23-25,) 28, 31, April (8, 12)
Active to disturbed on March 29-30, (April 3)

Amplifications of the solar wind from coronal holes are expected on March (18-22,) 23-27, April (3-8,) 14-?

Remark:
- Parenthesis means lower probability of activity enhancement and/or
lower reliability of prediction."


Jon, N0JK wrote on March 16: “There was a 6 meter Es opening last Friday March 10. It was open from Florida to W1, W2, and W3 between 1600-1800z. The W3DOG/b beacon was spotted in Florida.

W3DOG/B  17/03/10 1717Z  50071.1 fm28<>el87 woof woof   KD4ESV
W3DOG/B  17/03/10 1625Z  50071.0 FM28 589 IN FL EL87    WX4G

This is the second Es opening for the month of March, 2017.”

Later, he wrote: “Potential for aurora March 28-29.”


The National Science Foundation will abandon an historic solar observatory in October, but New Mexico State University with take charge and sustain it: http://bit.ly/2mxqFV0

The vernal equinox is very close! The days and weeks before and after are always a good time for HF propagation, and it is on March 20, this coming Monday.


A study on sunspot number re-calibration: http://bit.ly/2ngm1yi

Also, here is a piece on solar cycles suggesting that the next cycle may be larger than the current solar cycle: http://www.leif.org/research/Prediction-of-Solar-Cycles.pdf


For more information concerning radio propagation, see the ARRL Technical Information Service at http://arrl.org/propagation-of-rf-signals. For an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere.

An archive of past propagation bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation. More good information and tutorials on propagation are at http://k9la.us/.

Monthly propagation charts between four USA regions and twelve overseas locations are at http://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins.

Sunspot numbers for March 9 through 15, 2017 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 71.2, 71, 70, 70.1, 70.3, 69.6, and 69.8, with a mean of 70.3. Estimated planetary A indices were 15, 12, 6, 9, 3, 5, and 7, with a mean of 8.1. Estimated mid-latitude A indices were 10, 14, 4, 7, 2, 3, and 5, with a mean of 6.4.



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