Eight days with no sunspots, at least so far. Average daily sunspot number for our reporting week was down 33.6 points to zero. Earlier in this month we saw four days with a blank sun (sunspot number of zero) from June 3-6.
There were no sunspots during all of Field Day weekend.
The last time we saw a blank sun (before June 2016) was 2014. Just one day, on July 17, 2014. Sunspot number was zero, and only for one day. Prior to that, there were just two days in 2011, on January 27, and on August 14.
Prior to that there were 51 days with a blank sun in 2010, with 12 periods ranging from 1 to 13 days. The longest periods were 11 days beginning on May 9, 2010 and 13 days beginning on April 1, 2010.
These recent periods of no sunspot activity are a surprise to me, even though we are in a declining half of the solar cycle. I didn’t expect the extended periods with no sunspot activity would begin so early following the peak of Cycle 24. But perhaps we will see some extended periods of more sunspot activity, since we’ve seen in the past that nothing moves in a straight line up or down. There is plenty of variation.
Or perhaps that reference to memory suggests the classic gambler’s fallacy. This refers to the illogical feeling that because a particular ball in the lottery hasn’t been drawn for a long time that somehow it is overdue, making it more likely that the numbered ball will be drawn soon. This, of course, concerns only a random draw with all independent variables.
Mentioned earlier was the observation that the average daily sunspot number was zero over our reporting week (June 23-29) compared to 33.6 on the previous seven days. Average daily solar flux during the same two weeks dropped from 83.8 to 75.6.
Average daily planetary A index increased from 7 to 9, while the mid-latitude A index went from 6.9 to 9.1.
The latest prediction (June 30) sees solar flux at 75 on July 1-7, 80 on July 8, 80 on July 11, 82 on July 12-13, 80 on July 14-17, 78 on July 18-23, 77 on July 24 and 80 on July 25-31. Following this, the prediction shows solar flux rising two points for the first week in August.
Predicted planetary A index is 12, 30, 25, and 10 on July 1-4, 5 on July 5-7, then 10 on July 8-9, then 8, 20, 12 and 5 on July 10-13, 8 on July 14-15, 5 on July 16-18, then 15, 12 and 10 on July 19-21, and 5 on July 22-26, 10 on July 27 and 8 on July 28-29.
OK1MGW sends us his geomagnetic activity forecast for the period July 1-July 27, 2016.
Geomagnetic field will be:
Quiet on July 16-17, 26-27
Mostly quiet on July 1, 6, 14-15, 18, 24-25
Quiet to unsettled on July 4-5, 10, 13, 21-23
Quiet to active on July 7-9, 11-12, 19-20
Active to disturbed on July 2-3
Increases in solar wind from coronal holes are expected on July 2-3, 7-9, 11-12, and 19-20.
In line with the USAF/NOAA planetary A index forecast and the OK1MGW prediction, the Australian Space Weather Services issued a geomagnetic disturbance warning at 2346 UTC on June 30.
Geomagnetic conditions on July 2-3 are expected to increase to Active levels and at times possibly reaching Minor Storm levels in response to the high speed solar wind emanating from an equatorial coronal hole.
Expect quiet to minor storm levels on July 2 and quiet to active July 3.
Conditions were good during ARRL Field Day last weekend. There were no sunspots, but there were also no massive solar eruptions or geomagnetic storms.
Taking a quick look at our 3-month moving average of daily sunspot numbers ending June 30, the numbers starting with the three months ending on January 31 were 55.4, 53.5, 49, 45.3, 43.1 and 35.4. The falling progression continues. Our latest period at 35.4 is the lowest in the current cycle since the three months centered on January 2011, when the 3 month average was 35.3.
The last minimum was around August 2008 to March 2009.
Here is a recent article about the lack of sunspots: http://bit.ly/29djYnn
Lou, VK5EEE, sent in a couple of interesting questions, which I passed on to Carl, K9LA.
Here was Lou’s first question.
“I have observed on several occasions over the past 6 months or so, an unusual propagation, which I cannot explain. I have searched far and wide on the Internet, and short of an atmospheric nuclear explosion causing a strong ionization of E layer, which does not appear to have occurred based on Geiger counter readings, I find no explanation.
“Sporadic E, we are told, occurs from around 12m (25MHz) upwards, is that correct? Can it occur on 21 MHz? Can it ever occur on 20 meters? It appears to me not on 20 meters. Also, what I describe does not last a short time, as would be expected, but for hours. Short skip of 600 km at night on 20 meters should not normally be possible.
“At the same time as this short skip late evening propagation from VK5 to VK3 (dipole facing broadside to VK3 and HS at my VK5 QTH) the VK3 was using 5 element beam beaming to HS (same direction as VK5) and HS was beaming to VK3 with a 4 element beam. The VK3-VK5 was exceptionally strong 599+20db on my 8-meter-high dipole. Not to be expected, even more so with a 5 element beam during the middle of the day, most of the energy should pass way overhead. The VK3-HS were both 599 to each other, but HS-VK5 was only S4 from me, S7 from HS.
“Given it is taking place, and the phenomenal signal strengths, 20 or so dB above what would be normal via F layer propagation, would that be E layer propagation, and why is the E layer there?”
Carl, K9LA responded:
“With respect to your observation number 1, I downloaded ionosonde data from Canberra (the closest to your VK5 to VK3 path – we can get a general idea of what happened in the ionosphere) for Jan 1, 2016 to May 31, 2016. That’s 152 days of data, and data is taken every hour – that gives 3648 possible data points.
“For an E mode (110 km height), the elevation angle for the 600 km path is around 18 degrees. The value of foE must be greater than about 5 MHz to support 14 MHz for this short path. For an F mode (300 km height), the elevation angle is around 45 degrees. The value of foF2 must be greater than about 9.3 MHz to support 14 MHz.
“The foE data had 847 data points, so there is a lot of data missing. Of the data available, there’s nothing above 4.5 MHz.
“The foEs data had 1759 data points. That’s better – almost 50% of the possible data points. In your summer (January and February), there are many foEs values above 5.0 MHz. Towards your winter (May), there are still quite a few foEs values above 5.0 MHz.
“The foF2 data had 2887 data points (about 80% of the possible total). There were not many foF2 values above 9.3 MHz. Most foF2 values were 7 MHz and below.
“This cursory investigation suggests that Es could have been the mode. But your question asking if Es occurs on 20-Meters is very relevant. With Es layers being thin (I’ve seen values from 1 to 5 km), there just isn’t enough vertical extent of the layer to have pure refraction (bending) take place, and the ionization doesn’t appear to be enough for reflection. Thus in my mind the answer to your question appears to be ‘no, Es generally doesn’t happen on 20 meters.’ If foEs was much higher, then a thin layer might support reflection at 14 MHz.
“There is an ‘above-the-MUF’ mode with both the E region and F region when the operating frequency is somewhat above the MUF. This mode is believed to involve a scatter mechanism, which implies additional loss. Using the ‘above-the-MUF’ estimates of additional loss on 14 MHz says your observations could have been either E or F.
“And there’s also the possibility of a back-scatter mode, with the scatter region being somewhere northwest of you along the path to HS. That’s about as far as I can go with this. I don’t have a definite answer – that happens more than we’d like with some HF propagation observations due to the lack of suitable ionospheric data.”
For more information concerning radio propagation, see the ARRL Technical Information Service at http://arrl.org/propagation-of-rf-signals. For an explanation of the 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 June 23 through 29 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 77.5, 75.7, 77.1, 76.6, 75.4, 73.1, and 73.6, with a mean of 75.6. Estimated planetary A indices were 12, 12, 7, 11, 10, 7, and 4, with a mean of 9. Estimated mid-latitude A indices were 10, 10, 7, 11, 16, 6, and 4 with a mean of 9.1.