Propagation News – 12 November 2023
Last week was characterised by very unsettled geomagnetic conditions which took their toll on the high-frequency bands.
The Kp index hit seven on the 5 November, sparking visible aurora all over the UK. This also caused auroral conditions on the bands with many people commenting on the auroral flutter on the lower HF bands and hearing auroral-type signals on the 10m band.
Unfortunately, these conditions didn’t improve very quickly, and the upper bands were badly affected as the subsequent geomagnetic storm continued.
By late afternoon on the 6th, HF began to return to normal with MUFs over a 3,000km path hitting more than 28MHz again.
The solar flux index, at this point, was 146, with eleven C-class flares being detected on Monday, but nothing worse.
Unsettled geomagnetic conditions continued on and off until the morning of Thursday 9 November when the Kp index finally got down below four and stayed there.
A quick check of the 10m band on Thursday afternoon revealed the W1AW CW practice transmissions on 28.0675MHz, plus two to ten watt beacons audible from Gibraltar, Italy, Greece and the Eastern seaboard of the USA. The band was open, but not exactly humming!
Also on Thursday, the data feed to Propquest.co.uk failed, resulting in a lack of graphs for the F2-layer critical frequency and extrapolated MUFs. Let’s hope it returns quite quickly.
Next week, NOAA predicts that the solar flux index will be around 150 and the Kp index will be around 2 or 3. If that is the case, we can expect conditions to be a little better. But, as always, a coronal mass ejection could soon put an end to the fun with an increased Kp index and decreased MUFs.
VHF and up
The current spell of unsettled weather is likely to continue for another week at least, with some fairly strong weather systems possible, which could bring gales and heavy rain.
With fast-moving systems it’s pointless, with such a long lead time, to try and nail down the exact timings of each individual system. Once again, Tropo will not be a big player in VHF/UHF operating this week, except perhaps over this weekend, the 11 and 12 November, as a transient weak ridge crosses the country.
You might still see the odd ’spike’ of higher E-layer critical frequencies on the propquest.co.uk NVIS charts when it comes back online. Lately, these have been during the mid-morning period so maybe give the 10m and 6m bands a cursory check during the coming week. It’s not entirely clear why the bands have been so reliable during the recent week, but may be a response to meteor input.
We are approaching the peak of the Taurids meteor shower over the 12 and 13 November. This is followed by the much larger Leonids towards the end of next week on the 17 and 18 November. This also means that it’s worth listening for some meteor scatter signals throughout the next week or so.
There was a nice auroral opening on 6m up to 2m late in the afternoon on the 5 November, with the planetary Kp index reaching 6 to 7. This produced rare visual aurora sightings down to the south coast. Auroral CW and SSB signals sound ‘watery’ on the LF bands and very raspy and whispery on HF and VHF.
For EME operators, Moon declination is negative and falling again, reaching a minimum on Thursday 16 November. Path losses continue to fall and 144MHz sky noise is low, apart from Monday the 13 November when the Sun and Moon are close in the sky. From Wednesday, it rises to a high of 2,900 Kelvin on Thursday.
Category: GB2RS Propagation News
