Quick observations from the San Francisco Bay area in the "middle of the shortwave band"- While running about 3 watts into a Comet H422 rotatable 4-band dipole (fixed in a upwards V- general omni pattern), I noticed average path condx from coast to coast and to VE2 areas before the eclipse at 1015 pdt. Here are some 10 minute WSPR screen captures showing possible path reduction to E.VE and W4,5 areas just after the eclipse from my location, with condx returning and continuing "normal" for the rest of the afternoon. These are just general observations, and I have only glanced at the WSPR database snr/path info for my qth.. 73,Eric
Hi Eric; The drop out of the signal that you experienced was not the solar eclipse but a series of M and C class solar flares that happened at the same time of the eclipse. After the eclipse the earth experienced a Class 2 solar storm which was the worst in a couple of years! How much coverage of the sun did you get at your location? Alex - VE7DXW
Hi Eric, Thanks for the great observations. Your report is consistent with many other reports of HF propagation disturbances during the eclipse, including multiple WSPR stations, RBN, PSKReporter, and others. These have been coming into the HamSCI group from different users, and are consistent with a rapid ionospheric change across the penumbra to conditions more characteristic of the early evening hours. (The EUV shadow extends far outside the umbra into the penumbra, affecting a wide swath of the US.) Effects in the ionosphere were also measured directly with ionosondes in the shadow area and also with large systems like the worldwide GPS total electron content network and ionospheric radars. Formal raytracing analysis will occur soon. Along with that, science analysis is starting in the next few weeks (slowly, as all large science studies do), and we'll examine this effect closely. 73 Phil W1PJE For more information: http://hamsci.org
Eric, great data. Your observations are supported by observations made using the Millstone Hill Ionospheric Radar that saw a two fold drop in electron content in the F2 layer and thus 20M signals degraded during the eclipse. The M class flare that we had earlier before the eclipse, according to NOAA Space Weather conditions and levels, had no effect on the ionosphere during the eclipse. Joe, K1YOW
I too was more interested in how radio propagation was affected than putting on a pair of goggles and actually looking at it. My area was in an area of 90% totality and had it not been for the media hype, the eclipse would have gone unnoticed by me. I turned on my WSPRlite transmitter 3 days before the eclipse on 14mhz running 200mw to get somewhat of a "baseline" propagation pattern. I turned off the transmitter two days after the eclipse. I saw virtually no effect on 20 meter propagation that I could definitively attribute to the eclipse. I started watching the AM broadcast band on 700khz on the morning of the eclipse. There was still propagation and I was hearing WLW. As D layer absorption continued, the band went flat. During the maximum of the eclipse, there was very little change in the spectrum scope on my HF radio. About 30-60 minutes AFTER the maximum blocking of the sun, I started seeing small signals on the spectrum scope at 700 khz and a weak signal appeared. The signal strength gradually increased to the point I could identify what song(s) were playing. A quick search on radio-locator.com showed that WZOO, located in Asheboro, NC was the likely station. Their online presence confirmed this when I accessed their website and could hear the same music (with a slight latency). WZOO is a 1kw, single stick station about 108 miles due south of my location. I could see other stations showing on the spectrum scope at the same time. After another 30 minutes or so, the band again flattened out with no propagation until after sunset. The first attached picture is about 30 minutes after maximum eclipse. The second picture is of the same segment of band a few hours before the eclipse. The third picture is of the propagation plot on my WSPR transmitter during the maximum of the solar eclipse (I flagged the approximate point during the maximum eclipse). The fourth picture shows propagation profile 3 days before and two days after and flagging the complete conclusion of the moon covering the sun. From here, the eclipse had minimal effects on radio propagation. 73 Andy W4KDN
Alex, how do the effects of flares specifically follow an eclipse shadow instead of not being planetary wide? Also, why do we care about any solar storms after the eclipse? I also don't agree with your conclusion because that is not what the NOAA Space Weather records show. Just before and during the eclipse: the effective SSN was declining; aurora activity was slowly declining; the planetary Kp was declining; the effects of the M1 flare the day before had dissipated; the C class flare just before the eclipse had no effect on any propagation that would affect Eric's findings because it was too small. Joe, K1YOW
Because a solar flare - strong electromagnetic pulse will activate the D-Layer which absorbs radio waves. So if there is a solar flare during the eclipse the effect of moons shadow can be eliminated by the buildup of the D-Layer and you wont get any signals. Actually NOAA send out warnings that where displayed by the RF-Seismograph and the G2 storm was also predicted and announced by NOAA! All the best; Alex
Are you saying that a strong flare, strong enough to cause D region electron density increases, occurred DURING the eclipse itself? Otherwise, it's not relevant if it occurred AFTER the eclipse. K1YOW's plot shows a pretty small C class flare and that is not going to cause much if any D region increase. Also, K1YOW's plot clearly indicates that there was only weak to low geomagnetic activity (Kp = 3 or less) during the eclipse itself. A G2 storm did occur but AFTER the eclipse. Clarification is needed. 73 Phil W1PJE
Hi Phil; It actually did and it did cause a G2 storm in the process. Sometime if the magnetic fields are aligned just right a small flare can have a big impact on the geomagnetic field. The NOAA D-Region absorption website recorded very strong interaction during the eclipse. Here is the link: http://www.swpc.noaa.gov/communities/radio-communications All the best; Alex - VE7DXW
1) Sorry for being dense but what are you referring to when you say "It actually did"? What is the "It" and what is the "did"? 2) I would like to read further on the positive correlation you are implying between solar flares and geomagnetic activity. This is something that is not familiar to me. Can you point me to some journal articles? 3) I tried to find the NOAA plot showing significant D region absorption/effect during the eclipse, since the link you sent is to the real time NOAA space weather dashboard and the eclipse period is far behind it. The D region absorption plot is not available yet in their archives pages. Perhaps you can post this plot here so I can see what you are talking about? 73 Phil W1PJE
Thanks for the feedback guys! I also run Ionoprobe on Win10 in the background (but didn't think to look at it on aug21st..hi)
