[SFDXA] ARLP027 Propagation de K7RA

[William Marx]

> SB PROP @ ARL $ARLP027
> ARLP027 Propagation de K7RA
> 
> ZCZC AP27
> QST de W1AW  
> Propagation Forecast Bulletin 27  ARLP027
> From Tad Cook, K7RA
> Seattle, WA  July 1, 2016
> To all radio amateurs 
> 
> SB PROP ARL ARLP027
> ARLP027 Propagation de K7RA
> 
> Eight days with no sunspots, at least so far. Average daily sunspot
> number for our reporting week was down 33.6 points to 0. Earlier in
> this month we saw four days with a blank Sun (sunspot number of 0)
> 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 0, 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 Solar 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 0 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 21MHz? CAN IT EVER OCCUR on 20m? It
> appears to me not on 20m. Also, what I describe does not last a
> short time, as would be expected, but for hours. Short skip of 600km
> AT NIGHT on 20m, this 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 up 20m beaming to HS (same direction as
> VK5) and HS was beaming to VK3 with a 4ele beam up 22m. The VK3-VK5
> was exceptionally strong 599+20dB on my 8m high dipole. Not to be
> expected, even more so with a 5ele 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."
> 
> If you would like to make a comment or have a tip for our readers,
> email the author at k7ra at arrl.net.
> 
> For more information concerning radio propagation, see the ARRL
> Technical Information Service web page 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.
> NNNN
> /EX