Solar and Propagation Topics Carl Luetzelschwab K9LA k9la@arrl.net https://k9la.us Huntsville Hamfest August 2019 K9LA

Huntsville Hamfest August 2019 K9LA Who Is K9LA? Novice license in 1961 (WN9AVT) General in 1962, Extra in 1977 BSEE/MSEE Purdue University RF design engineer for Motorola and Magnavox/Raytheon Solid-state RF power amps Wife is Vicky AE9YL (first licensed as KB5EAM in 1987) ARRL Central Div Vice Director Novice/early General NC-60, VF-1, DX-35 YK9A Feb 2001 Huntsville Hamfest August 2019 K9LA

Huntsville Hamfest August 2019 K9LA Topics We’ll Touch On Cycle 24 update Current solar minimum Propagation at solar minimum The NEW sunspot numbers Cycle 25 predictions Grand Solar Minimums Propagation predictions Comments on 160m Huntsville Hamfest August 2019 K9LA

Huntsville Hamfest August 2019 K9LA Cycle 24 Update I don’t think we’ve reached the bottom yet For all intents and purposes, the higher bands are at solar minimum we are here Why two peaks? Is the 10.7 cm sf prediction of 58.9 reasonable? How long will we be at solar minimum? Huntsville Hamfest August 2019 K9LA

Why Two Peaks? Solar hemisphere asymmetry The Sun appears to be in new territory In other words, we haven’t seen anything like this prior to Cycle 22 Huntsville Hamfest August 2019 K9LA

How Low Can Solar Flux Go? Slide 4 predicts a 10.7 cm solar flux of 58.9 What’s the lowest we’ve ever seen? t the time I’m writing this, the SWPC has predictions of 58.9 for the 10.7 cm solar flux K9LA 58.9 suggests we’re in for a deep solar minimum Huntsville Hamfest August 2019 K9LA

Minimums Between Cycles 18-19, 19-20, 20-21, 21-22, 22-23 My definition of solar minimum – when the smoothed sunspot number is below 20 We became accustomed to short solar minimums – about 2 years Huntsville Hamfest August 2019 K9LA

Minimum Between Cycles 23-24 Last solar minimum was almost 5 years! Huntsville Hamfest August 2019 K9LA

The Current Solar Minimum K9LA We appear to be tracking another long solar minimum period Huntsville Hamfest August 2019 K9LA

Solar Minimum – Winter F2 MUFs December, zero sunspots, 1300 UTC, monthly median 3000 km F2 MUFs Proplab Pro V3, K9LA Worldwide 20m openings for NA during the day and early evening 17m open on ‘good’ days (more on this later) Huntsville Hamfest August 2019 K9LA

Huntsville Hamfest August 2019 K9LA Elevation Angles to EU From N2IC’s subset of N6BV data Huntsville Hamfest August 2019 K9LA

Elevation Angles to USA Low angles important at solar minimum – imply long distance hops Huntsville Hamfest August 2019 K9LA

What Does A Long Minimum Tell Us? K9LA A long solar minimum strongly suggests the next cycle will be small Huntsville Hamfest August 2019 K9LA

Huntsville Hamfest August 2019 K9LA Solar Cycles Overlap Can tell what cycle a sunspot belongs to by the latitude of emergence and the polarity New sunspots emerge at higher latitudes As cycle progresses, sunspots emerge at lower latitudes Sunspots have magnetic field going out and coming back in (a loop) Huntsville Hamfest August 2019 K9LA

Integrity of Sunspot Data Lots of gaps in the early data Cycles 1-5 Cycles 6-9 How good is this data? Huntsville Hamfest August 2019 K9LA

We Have NEW Sunspot Numbers 4 workshops held starting in Sept 2011 to review old data Recent V2 data about 1.4 times V1 data K9LA Royal Observatory of Belgium – started reporting NEW data (V2) as of July 1, 2015 NOAA still reports OLD data (V1) Will change at solar min (soon!) Huntsville Hamfest August 2019 K9LA

Huntsville Hamfest August 2019 K9LA First Sunspot of Cycle 25 The first sunspot of Cycle 25 was seen on Dec 20, 2016 But very short duration – not assigned an Active Region number Huntsville Hamfest August 2019 K9LA

Huntsville Hamfest August 2019 K9LA More Cycle 25 Sunspots April 8, 2018 - November 17, 2018 - May 28, 2019 - July 1, 2019 But these were also of short duration No AR numbers Finally, a long duration Cycle 25 sunspot on July 8, 2019 Assigned AR 2744 Likely the first ‘official’ Cycle 25 sunspot solar equator Remember Cycle 24 sunspots are black-leading white in the southern hemisphere Huntsville Hamfest August 2019 K9LA

Huntsville Hamfest August 2019 K9LA Cycle 25 Predictions I’ve seen 10 predictions for Cycle 25 Lowest – 2/3 of Cycle 24 Highest - 154 Some confusion – are the predictions in terms of the OLD (V1) sunspot numbers or the NEW (V2) sunspot numbers? Remember recent V2 is ~1.4 higher than V1 General summary – most believe Cycle 25 will be another small one Huntsville Hamfest August 2019 K9LA

Other Data Suggesting Small Cycle Historical data suggests we’ve entered a period of small solar cycles Schwabe ~ 11 years Hale ~ 22 years Gleissberg 70-100 years Huntsville Hamfest August 2019 K9LA

Grand Solar Minimums (GSMs) Sun’s mag field weak Solar min I have not found any data later than the 1950s Our recorded history starts here with Cycle 1 Sun’s mag field strong Solar max More about this on slide 29 GSMs occur on a ‘regular’ basis Huntsville Hamfest August 2019 K9LA

Grand Solar Minimums (GSMs) The Maunder Minimum was a GSM The Dalton Minimum was also a GSM But the Dalton Minimum still had sunspots GSM does not necessarily mean “no sunspots” Just several cycles below an average solar cycle Dalton Minimum Huntsville Hamfest August 2019 K9LA

Propagation Predictions We do not have daily predictions Today’s ionosphere does not correlate well with today’s sunspot number or 10.7 cm solar flux Why not? Because two other parameters modify the amount of ionization Geomagnetic field activity Events in the lower atmosphere coupling up to the ionosphere The result? Our propagation predictions are statistical in nature over a month’s time frame Huntsville Hamfest August 2019 K9LA

Huntsville Hamfest August 2019 K9LA Monthly Median Our propagation predictions give monthly medians for MUF and signal strength 50% probability – half the days of the month There are distributions about the median In general, on any given day The MUF could be ~10% higher to ~20% lower The signal strength could be ~2 S-units higher to ~ 3 S-units lower The NEW sunspot numbers don’t help And our propagation predictions do not capture very short-term events Huntsville Hamfest August 2019 K9LA

Huntsville Hamfest August 2019 K9LA 2018 CA QSO Party – Oct 6,7 Sat Sun K9LA 10m open! No W6s on 10m on the 6th (Saturday) K index spiked up on the 7th (Sunday) Positive phase of this geomagnetic storm increased mid and low latitude ionization – 10m opened to W6 Check the higher bands when the K index spikes up Huntsville Hamfest August 2019 K9LA

Huntsville Hamfest August 2019 K9LA 160-Meters What’s going on with 160-Meters? Shouldn’t it be better? We all grew up believing solar minimum was best for the low bands Cycle 24 decline – coronal holes Cycle 24 maximum – flares and CMEs last solar minimum Possible answer - Earth’s magnetic field not quiet enough yet Another possibility - are all solar minimums equal? Can a deep solar minimum hinder 160m? Huntsville Hamfest August 2019 K9LA

Galactic Cosmic Rays (GCRs) When the Sun’s magnetic field is weak, more GCRs get into our atmosphere Two byproducts are neutrons and electrons Minimum between Cycles 23/24 had the most GCRs in recorded history Min between Cycles 24/25 could be higher Huntsville Hamfest August 2019 K9LA

Additional Electrons Down Low GCRs are mostly high-energy protons Cause additional electrons through collisions with atmospheric constituents Ionization rates are in the literature 160m cannot tolerate many more electrons with respect to absorption Deep solar min may adversely impact 160m valley K9LA Huntsville Hamfest August 2019 K9LA

Huntsville Hamfest August 2019 K9LA Final Comments Why an 11-year cycle? Full article https://arxiv.org/abs/1803.08692 Get handout or e-mail k9la@arrl.net (2 page summary) video https://www.youtube.com/watch?v=tBScyiYIhS4 Two-cell dynamo article predicts very small Cycles 25 and 26 (and 27 in a follow-on article) https://iopscience.iop.org/article/10.1088/0004-637X/795/1/46/pdf What’s the definition of ‘official’ solar minimum? Lowest sunspot number? Lowest 10.7 cm solar flux? Lowest total solar irradiance? Lowest EUV? Lowest Ap? Equal number of new and old sunspots? Days with zero sunspots? Huntsville Hamfest August 2019 K9LA

Huntsville Hamfest August 2019 K9LA Summary It looks like this solar minimum will be a long one – min in late 2019/early 2020 Low elevation angles dominate above 20m Cycle 25 is likely to be small We’re likely entering (or in) a Grand Solar Min But that doesn’t mean “no sunspots” Impact to 160m questionable in my mind The low bands and 20m/17m will still offer worldwide DX QSOs – and don’t forget Es The digital modes will make this solar minimum the most active in history on the higher bands Huntsville Hamfest August 2019 K9LA