Propagation News – 13 December 2020
We said last week that it would be hard to predict what would happen over the next seven days – and that turned out to be true. The coronal hole we mentioned last week didn’t really amount to much, and sunspot region 2790 didn’t either. As a result, the solar flux index fell to 82 by Thursday, with region 2790 shrinking and with no other sunspots on the visible face of the Sun.
A B-class solar flare on the 7th of December resulted in a coronal mass ejection that impacted the Earth in the early hours of the 10th. This pushed the Kp index to four, but the effects were relatively short-lived and the index was back down to one by midday. Propquest’s ionosonde readings reflected the CME’s effects in the early hours, but showed the MUF over a 3,000km path was back to 21-24MHz by mid-morning. There were other minor solar flare events during the week, but nothing as intense as the flare on the 7th.
There was DX around last week. Bob, VP8LP in the Falkland Islands and numerous Brazilian stations have been audible in the afternoon on 10m FT8. Australia and New Zealand have both been workable on 20m FT8 in the morning as well.
NOAA got its SFI prediction pretty much spot-on last week. It said we could expect to see it in the low 80s by the end of the week and so it was! Next week NOAA says it will be around 86, but we can expect poorer conditions around the 18th and 19th due to a geomagnetic disturbance. Region 2783 returns again this week, but the prediction is that is unlikely to be that active.
So this week, focus your DXing efforts at the beginning of the week as conditions may be worse by next weekend.
VHF and up
It will be another quiet week for Tropo propagation, with the next few days looking to be once again dominated by unsettled weather. Low pressure mostly to the northwest of Britain will feed a succession of fronts and bands of rain across the country. This makes rain scatter a probable mode for the GHz bands, and not much chance to cheer up any Tropo operators. It may also be rather breezy in some areas and mostly milder again.
The Geminids meteor shower is well under way and peaks tomorrow on the 14th, so expect high activity on the digimode frequencies on all the VHF bands. If you have 100 watts and a beam on two or six metres, why not try an SSB sked at the peak? All that chanting of callsigns and “Roger, Roger” can be very therapeutic! The high ZHR of 150 means that this is quite possible. Also, look for signal bursts around 49.750MHz from the few remaining Eastern European TV carriers, and on 143.050MHz for the Graves bistatic radar from France.
The Moon is at minimum declination on Tuesday so there are short visibility windows all week. Losses are low with the Moon at perigee today. 144MHz sky noise is high and increasing and the Sun and Moon are very close tomorrow and low, not falling below 500 kelvin until Wednesday.
And that’s all from the propagation team this week.
Category: GB2RS Propagation News
