1. Fort Wayne DX Convention July 2015 Solar Impact on Propagation Carl Luetzelschwab Ft Wayne, IN k9la@arrl.net (e-mail) http://k9la.us (web site)

2. Fort Wayne DX Convention July 2015 Who Am I? Began as an SWL in 6 th grade Began as an SWL in 6 th grade Mom and Dad bought me a National NC-60 Special receiver Mom and Dad bought me a National NC-60 Special receiver 31m and 25m were my best bands 31m and 25m were my best bands NC-60 had adequate sensitivity and decent bandspread for those frequenciesNC-60 had adequate sensitivity and decent bandspread for those frequencies “Licensed” thru Popular Electronics as WPE9BQH “Licensed” thru Popular Electronics as WPE9BQH WN9AVT in October 1961 (just turned 14) WN9AVT in October 1961 (just turned 14) Selected K9LA in 1977Selected K9LA in 1977 Still like to SWL with vintage receivers Still like to SWL with vintage receivers NC-60NC-60 Drake 2B with additional crystalsDrake 2B with additional crystals Have an SX-100 (general coverage) that needs workHave an SX-100 (general coverage) that needs work

3. Fort Wayne DX Convention July 2015 Solar Impact on Propagation Let’s divide AM broadcast frequencies to 30 MHz into three segments Let’s divide AM broadcast frequencies to 30 MHz into three segments Above about 16 MHzAbove about 16 MHz MUF-driven bands MUF-driven bands AM broadcast up to about 9 MHzAM broadcast up to about 9 MHz Absorption-driven bands Absorption-driven bands Between 9 MHz and 16 MHzBetween 9 MHz and 16 MHz Transition bands Transition bands We’ll also review disturbances to propagation We’ll also review disturbances to propagation

4. Fort Wayne DX Convention July 2015 MUF-Driven Bands above about 16 MHz Ionospheric absorption is inversely proportional to the square of the frequency Ionospheric absorption is inversely proportional to the square of the frequency The higher the frequency, the lower the ionospheric absorptionThe higher the frequency, the lower the ionospheric absorption Minimal absorption on these frequenciesMinimal absorption on these frequencies Amount of refraction is inversely proportional to the square of the frequency Amount of refraction is inversely proportional to the square of the frequency The higher the frequency, the less the bendingThe higher the frequency, the less the bending Need more ionization to refract RF back to EarthNeed more ionization to refract RF back to Earth Daytime!Daytime! Size matters – the size of the solar cycle, that is! Size matters – the size of the solar cycle, that is! daytime the higher the frequency, the longer the hop and the less the absorption

5. Fort Wayne DX Convention July 2015 All Solar Cycles Cyclic in nature Cyclic in nature Three periods of larger cycles Three periods of larger cycles Two periods of smaller cycles Two periods of smaller cycles Are we headed for a period of smaller cycles? Are we headed for a period of smaller cycles? Dalton Minimum

6. Fort Wayne DX Convention July 2015 Duration of Solar Minimums Three periods of short duration minimums Three periods of short duration minimums Two periods of long duration minimums Two periods of long duration minimums Looks like we’re entering a third period of long minimums Looks like we’re entering a third period of long minimums Note the relationship between this graph and the graph on the previous slide Note the relationship between this graph and the graph on the previous slide

7. Fort Wayne DX Convention July 2015 Solar Max vs Previous Solar Min The longer the solar minimum, the smaller the next cycle

8. Fort Wayne DX Convention July 2015 Cycle 24 Cycle 24 is the smallest in our lifetimes Cycle 24 is the smallest in our lifetimes Early predictions for Cycle 25 say it may be even smaller! Early predictions for Cycle 25 say it may be even smaller! Not good for the higher frequenciesNot good for the higher frequencies

9. Fort Wayne DX Convention July 2015 Grand Solar Minimum Are we going to have another Maunder Minimum? Are we going to have another Maunder Minimum? Fact: we can’t see sunspots when the magnetic field around them is less than about 1500 Gauss Fact: we can’t see sunspots when the magnetic field around them is less than about 1500 Gauss From 1998 thru 2010 the magnetic field around sunspots appeared to be headed towards 1500 Gauss, but the decrease appears to have leveled off From 1998 thru 2010 the magnetic field around sunspots appeared to be headed towards 1500 Gauss, but the decrease appears to have leveled off

10. Fort Wayne DX Convention July 2015 Summary of MUF-Driven Bands We may not have many opportunities on the higher frequencies during the next several cycles We may not have many opportunities on the higher frequencies during the next several cycles Regardless, best seasons for the northern hemisphere are the fall, winter and spring months Regardless, best seasons for the northern hemisphere are the fall, winter and spring months Daytime is best, but several hours past sunset is okay due to slow F2 region recombination Daytime is best, but several hours past sunset is okay due to slow F2 region recombination Comment about sunspots and 10.7 cm solar flux Comment about sunspots and 10.7 cm solar flux Both are proxies for true ionizing radiationBoth are proxies for true ionizing radiation F region: 10-100 nm F region: 10-100 nm E region: 1-10 nm E region: 1-10 nm D region: 0.1-1.0 nm and 121.5 nm D region: 0.1-1.0 nm and 121.5 nm Daily sunspot number or 10.7 cm solar flux does not correlate well with what the ionosphere is doing todayDaily sunspot number or 10.7 cm solar flux does not correlate well with what the ionosphere is doing today Longer term correlation is best – smoothed solar index and monthly median ionospheric parametersLonger term correlation is best – smoothed solar index and monthly median ionospheric parameters

11. Fort Wayne DX Convention July 2015 Absorption-Driven Bands below about 9 MHz Again, ionospheric absorption is inversely proportional to the square of the frequency Again, ionospheric absorption is inversely proportional to the square of the frequency The lower the frequency, the higher the absorptionThe lower the frequency, the higher the absorption Maximum absorption on these frequenciesMaximum absorption on these frequencies Nighttime!Nighttime! Again, amount of refraction is inversely proportional to the square of the frequency Again, amount of refraction is inversely proportional to the square of the frequency The lower the frequency, the more the bendingThe lower the frequency, the more the bending Don’t need more ionization to refract RF back to EarthDon’t need more ionization to refract RF back to Earth nighttime The lower the frequency, the shorter the hop and the more the loss – caveat for loss at LF

12. Fort Wayne DX Convention July 2015 A Limit to Multi-Hop Since the lower frequencies have hops that are shorter and incur more loss (even at night), worldwide reception must be via multi-hop (many successive hops) Since the lower frequencies have hops that are shorter and incur more loss (even at night), worldwide reception must be via multi-hop (many successive hops) But there’s a problem – each hop takes its toll on signal strength due to ionospheric absorption and ground reflection loss But there’s a problem – each hop takes its toll on signal strength due to ionospheric absorption and ground reflection loss How far can low frequency RF go before it’s below the noise level at a receiving station (usually defined by atmospheric and/or man-made noise) How far can low frequency RF go before it’s below the noise level at a receiving station (usually defined by atmospheric and/or man-made noise) It’s easy to estimate this using the Friis transmission equation It’s easy to estimate this using the Friis transmission equation P(rcv) = P(xmt) + Gain(xmt ant) + Gain(rcv ant) – (free space path loss) – (absorption) – (gnd refl loss) – (polarization mismatch)P(rcv) = P(xmt) + Gain(xmt ant) + Gain(rcv ant) – (free space path loss) – (absorption) – (gnd refl loss) – (polarization mismatch) On 1.8 MHz with 1.5 kW and 0 dBi antennas, signal goes below the average noise level at around 10,000 km On 1.8 MHz with 1.5 kW and 0 dBi antennas, signal goes below the average noise level at around 10,000 km This is why ducting is invokedThis is why ducting is invoked

13. Fort Wayne DX Convention July 2015 Ducting Mechanism Natural mechanism for ducting in the dark ionosphere Natural mechanism for ducting in the dark ionosphere Electron density valley above the E region peakElectron density valley above the E region peak RF refracts successively between the top of the E region and the lower F region RF refracts successively between the top of the E region and the lower F region RF in the duct avoids ionospheric absorption and ground reflection losses RF in the duct avoids ionospheric absorption and ground reflection losses

14. Fort Wayne DX Convention July 2015 Ducting Example Ray trace is from Sudan (STØRY) to Fort Wayne (K9LA) Ray trace is from Sudan (STØRY) to Fort Wayne (K9LA) Ray tracing shows it is easy to get into a duct, but getting out of a duct in the dark ionosphere with ray tracing is not easy Ray tracing shows it is easy to get into a duct, but getting out of a duct in the dark ionosphere with ray tracing is not easy May require irregularities that we know are there but are not in the modelMay require irregularities that we know are there but are not in the model The ionosphere is not homogeneousThe ionosphere is not homogeneous Ducting likely occurs from AM broadcast thru MF Ducting likely occurs from AM broadcast thru MF ducting increases the limit imposed by multi-hop

15. Fort Wayne DX Convention July 2015 Signal Enhancements Another way to get out of a duct is to encounter a tilted ionosphere around sunrise (and maybe sunset) Another way to get out of a duct is to encounter a tilted ionosphere around sunrise (and maybe sunset) The result is a significant increase in signal strength for a short period of time when the signal comes out of the duct The result is a significant increase in signal strength for a short period of time when the signal comes out of the duct Sunrise enhancement of 3QD (Australia) at Victoria, BC on 1548 KHz on May 14, 1998 from “Medium-Frequency Sunrise Enhancements”, Nick Hall-Patch, QEX, July/August 2001 (reprints available)

16. Fort Wayne DX Convention July 2015 Solar Minimum Best, Right? Old adage is the low frequency bands are best at solar minimum Old adage is the low frequency bands are best at solar minimum For paths near the terminator, that’s probably correct as ionizing radiation can scatter into the dark ionosphere For paths near the terminator, that’s probably correct as ionizing radiation can scatter into the dark ionosphere For paths well in darkness, solar max is similar to solar min For paths well in darkness, solar max is similar to solar min Can solar min be too deep? Perhaps! Can solar min be too deep? Perhaps! Impact of GCRsImpact of GCRs GCRs contribute to absorption

17. Fort Wayne DX Convention July 2015 Summary of Absorption-Driven Bands Nighttime (dark ionosphere) is best Nighttime (dark ionosphere) is best Always check around sunrise/sunset on both ends of the path Always check around sunrise/sunset on both ends of the path Back when WOWO on 1190 KHz here in Fort Wayne was 50,000 Watts and a Clear-Channel, they received reception reports from India Back when WOWO on 1190 KHz here in Fort Wayne was 50,000 Watts and a Clear-Channel, they received reception reports from India WOWO selected antenna site for best ground conditions (highest conductivity)WOWO selected antenna site for best ground conditions (highest conductivity) For more on ducting and enhancements, read “Ducting and Spotlight Propagation on 160m”, Carl Luetzelschwab, CQ, December 2005 (reprints available)

18. Fort Wayne DX Convention July 2015 Transition Bands Between 9 MHz and 16 MHz Not as dependent on MUF as the higher frequency bands Not as dependent on MUF as the higher frequency bands Not as dependent on absorption as the lower frequency bands Not as dependent on absorption as the lower frequency bands They are essentially good at solar min and at solar max, and during the day and during the night They are essentially good at solar min and at solar max, and during the day and during the night My two favorite SWL bands (31m and 25m) and 19m fall into this range My two favorite SWL bands (31m and 25m) and 19m fall into this range These three bands are good all-around frequencies for international SWLingThese three bands are good all-around frequencies for international SWLing

19. Fort Wayne DX Convention July 2015 Disturbances to Propagation In March 2002, NOAA defined three categories of disturbances to propagation – G, S, R In March 2002, NOAA defined three categories of disturbances to propagation – G, S, R All three are caused by CMEs/coronal holes and big solar flares All three are caused by CMEs/coronal holes and big solar flares

20. Fort Wayne DX Convention July 2015 Three Categories G refers to Geomagnetic Storms G refers to Geomagnetic Storms Caused by gusts in solar wind from CMEs (coronal mass ejections) and high speed streams from coronal holesCaused by gusts in solar wind from CMEs (coronal mass ejections) and high speed streams from coronal holes Can cause auroral absorption, auroral-E, depleted F regionCan cause auroral absorption, auroral-E, depleted F region S refers to Solar Radiation Storms S refers to Solar Radiation Storms Caused by energetic protons from big solar flaresCaused by energetic protons from big solar flares Can increase D region absorption in the polar cap (PCA)Can increase D region absorption in the polar cap (PCA) refers to Radio Blackouts R refers to Radio Blackouts Caused by electromagnetic radiation from big solar flaresCaused by electromagnetic radiation from big solar flares X-ray flares (.1-1 nm wavelengths) of X or M class X-ray flares (.1-1 nm wavelengths) of X or M class Can increase D region absorption on daylight side of EarthCan increase D region absorption on daylight side of Earth For all three, scale is 1 to 5 For all three, scale is 1 to 5 1 is minor and 5 is extreme, and correspond to specific criteria1 is minor and 5 is extreme, and correspond to specific criteria Details at http://www.swpc.noaa.gov/Data/info/WWVdoc.htmlDetails at http://www.swpc.noaa.gov/Data/info/WWVdoc.html

21. Fort Wayne DX Convention July 2015 The Big Picture

22. Fort Wayne DX Convention July 2015 Impact In order of “least” impact to “most” impact In order of “least” impact to “most” impact Radio blackout (R)Radio blackout (R) No warning, but usually short duration – an hour or two No warning, but usually short duration – an hour or two Lower frequencies impacted longer Lower frequencies impacted longer Only affects daylight side of Earth Only affects daylight side of Earth Solar radiation storm (S)Solar radiation storm (S) A couple hours warning, can last a day or two A couple hours warning, can last a day or two Only affects propagation across the polar cap Only affects propagation across the polar cap Geomagnetic storm (G)Geomagnetic storm (G) A day or two warning, can last for days A day or two warning, can last for days Adversely affects high and mid latitude ionosphere both day and night Adversely affects high and mid latitude ionosphere both day and night Can enhance low latitude ionosphere Can enhance low latitude ionosphere In general we want G, S, R ratings to be 1 or less In general we want G, S, R ratings to be 1 or less

23. Fort Wayne DX Convention July 2015 Mitigation for Disturbances low freqs. Australia.

24. Fort Wayne DX Convention July 2015 June 22/23 Disturbances The high K indices are the result of a CME or coronal hole The high K indices are the result of a CME or coronal hole Could have adverse impact on F2 regionCould have adverse impact on F2 region When you see the K index that high for multiple 3-hr periods, you have to wonder about solar radiation storms and radio blackouts due to a concurrent big flare When you see the K index that high for multiple 3-hr periods, you have to wonder about solar radiation storms and radio blackouts due to a concurrent big flare www.swpc.noaa.gov/products/planetary-k-index

25. Fort Wayne DX Convention July 2015 June 22/23 Disturbances - CME First halo CME June 18 at 1724 UTC First halo CME June 18 at 1724 UTC Second halo CME June 19 at 0845 UTC Second halo CME June 19 at 0845 UTC Third, and fastest, halo CME June 21 at 1900 UTC Third, and fastest, halo CME June 21 at 1900 UTC The third CME caught up with the earlier two to add to the disturbance The third CME caught up with the earlier two to add to the disturbance www.swpc.noaa.gov/products/products/lasco-coronograph

26. Fort Wayne DX Convention July 2015 June 22/23 Disturbances – F2 Region Depleted F2 region at all latitudes in northern hemisphere Depleted F2 region at all latitudes in northern hemisphere Depleted F2 region at high and mid latitudes in southern hemisphere Depleted F2 region at high and mid latitudes in southern hemisphere Remember this is a model based on how the K index is developing – should be able to confirm with ionosonde data Remember this is a model based on how the K index is developing – should be able to confirm with ionosonde data www.swpc.noaa.gov/products/storm-time-empirical-ionospheric-correction

27. Fort Wayne DX Convention July 2015 June 22/23 Disturbances - Aurora Watch it here – the orange-red area is where visible aurora is likely to occur – caused by low energy electrons Watch it here – the orange-red area is where visible aurora is likely to occur – caused by low energy electrons It tells us nothing about radio aurora from high energy electrons It tells us nothing about radio aurora from high energy electrons www.swpc.noaa.gov/products/aurora-30-minute-forecast

28. Fort Wayne DX Convention July 2015 June 22/23 Disturbances - Electrons These measurements are at geosynchronous altitudes These measurements are at geosynchronous altitudes When the K index goes up, electrons trapped in the magnetosphere are released When the K index goes up, electrons trapped in the magnetosphere are released Guided to the high latitudes by magnetic field lines Guided to the high latitudes by magnetic field lines Precipitating electrons (that cause auroral displays) do not directly come from the Sun Precipitating electrons (that cause auroral displays) do not directly come from the Sun www.swpc.noaa.gov/products/goes-electron-flux

29. Fort Wayne DX Convention July 2015 June 22/23 Disturbances – Xray Flux bunch of big flares M2.0 M2.6 M3.8 M6.5 M1.1 www.swpc.noaa.gov/products/goes-x-ray-flux

30. Fort Wayne DX Convention July 2015 June 22/23 Disturbances – Proton Flux started increasing early on June 21 www.swpc.noaa.gov/products/goes-proton-flux

31. Fort Wayne DX Convention July 2015 June 22/23 Disturbances – Absorption and Radio Blackouts Increased absorption from protons funneling into the polar cap – solar radiation storm (A) Increased absorption from protons funneling into the polar cap – solar radiation storm (A) Increased absorption from electromagnetic radiation on dayside of Earth – radio blackout (B) Increased absorption from electromagnetic radiation on dayside of Earth – radio blackout (B) A A B www.swpc.noaa.gov/products/d-region-absorption-predictions-d-rap

32. Fort Wayne DX Convention July 2015 Summary SWLing on the higher frequencies may not be productive for the next several solar cycles SWLing on the higher frequencies may not be productive for the next several solar cycles SWLing on the lower frequencies should generally be good due to a small cycle SWLing on the lower frequencies should generally be good due to a small cycle May be dependent on how smallMay be dependent on how small Impact of GCRs Impact of GCRs SWLing on the middle frequencies should be just fine SWLing on the middle frequencies should be just fine Lots of space weather data available to assess disturbances to propagation Lots of space weather data available to assess disturbances to propagation