Propagation News – 22 October 2023
We had a quieter week, with both lower sunspot numbers and better geomagnetic conditions. The Solar Flux Index was at 135 on Thursday the 19 October, down from 156 the week before. Let’s hope this is a temporary lull in Solar Cycle 25’s progression.
We had no M-class or higher flares to contend with and the Kp index was generally below 3 all week. Only on Thursday did things start to become a little more unsettled as the Kp index climbed to 3.67 in the morning, with warnings that worse may be to come due to a coronal mass ejection on the 16 October.
So, the earlier part of the week was best for HF propagation with many stations reporting DX contacts including T2C, a German DXpedition to Tuvalu, and YL2GM’s one-person DXpedition to Tristan da Cunha.
It’s nice to see DX opening up, especially on the higher bands.
Propquest.co.uk reports that, generally, the maximum useable frequency over a 3,000km path remains above 28MHz during daylight hours so make the most of the 10 and 12m bands. The maximum usable frequency, or MUF, is the highest radio frequency that can be used for transmission between two points on the Earth by reflection from the ionosphere.
Next week NOAA predicts that the Solar Flux Index will rise to around 145 all week while geomagnetic conditions are predicted to be stable with a Kp around 2 to 3. But, as always, watch out for coronal mass elections and their impact.
VHF and up
We are struggling to find anything optimistic regarding Tropo in this unsettled spell of weather and again it may well be down to rain scatter to provide the entertainment.
Once out of the summer thunderstorm season, the results are rarely as good, even though you’ll be spoiled for choice! There will be a transient weak ridge over some eastern areas on Tuesday, but only acting as a separator between the lows and not expected to be effective for Tropo.
Incidentally, in this fairly typical spell of unsettled autumnal weather, strong winds and heavy rain can be a notable feature and puts stress on antennas and coax, so make a note of any weak points and use the next fine spell to put things right!
What propagation remains is the usual stop-gap pair of modes – meteor scatter and aurora – both of which could be worth checking during the coming week.
A reminder that the Orionids shower, active from the 2 October to the 7 November, peaks today, the 22 October, with an average Zenithal Hourly Rate, or ZHR, of around 20.
For EME operators, Moon declination reached minimum on Friday 20 Ocotber so the following week will see lengthening Moon windows. Next Thursday’s perigee means path losses are at their lowest this week. 144MHz sky noise starts high but falls throughout the coming week remaining low to moderate.
Category: GB2RS Propagation News
