Propagation News – 25 February 2024

We’ve had two X-class solar flares over the past few days. The first occurred at 2307UTC on 21 February, so didn’t affect the UK at all. The second erupted at 0632UTC on 22 February and was too early to affect the ionosphere in this region. However, HF paths to the east may have been affected.

However, active region 3590 could cause more problems as it rotates into an Earth-facing position. Look out for more flares and potential coronal mass ejections as we head into the weekend.

Another problem is a coronal hole on the solar equator, which was Earth-facing on Friday 23 February and could lead to an increased Kp index today, the 25 February, if its associated Bz magnetic field points south.

Although there are only two sunspot groups visible, the solar flux index is 170, showing just how potent these spots are.

Daytime MUFs over a 3,000km path are still exceeding 35MHz, while night-time MUFs over a similar distance struggle to get above 10 to 11MHz.

With the daytime MUF so high, it is a good opportunity to check for low-power 10m beacons. The RSGB’s Propagation Studies Committee has just released a new 10m beacon list, which has been created from scratch using the reverse beacon network and help from amateurs around the world.

The new beacon list, which can be found under the Propagation section of the RSGB website should be more useful than its predecessor as it is based on actual beacons that have been received. But if you hear any beacon that is not on the list, please inform Steve, G0KYA at psc.chairman@rsgb.org.uk

Next week, NOAA predicts that the solar flux index may decline a little into the 160s. As for geomagnetic conditions, it all depends upon what happens with active region 3590. We could be in for a rough ride, or things could be fine – let’s wait and see.

VHF and up

The current spell of unsettled weather continues, and this means that Tropo won’t be worth waiting for, other than any temporary short-lived early morning temperature inversions, especially if accompanied by misty low cloud or fog.

The main part of the story is again rain scatter, which will have plenty of opportunity to shine in the period to the end of the coming week. Summer thunderstorms are usually full of large raindrops, while winter systems are generally less intense but, in the absence of much else, it’s still worth considering for those on the GHz bands.

The other propagation modes of meteor scatter or aurora are even longer shots, but they may still crop up. The best time for random meteor scatter QSOs is around dawn.

Lastly, the doldrums for Sporadic-E propagation are still with us and don’t expect too much until we are well into April, even on the 10m band.

The high solar flux could see some trans-equatorial 50MHz openings if the Kp index remains low, especially for the far south and west of the UK.

For EME operators, Moon declination starts the weekend positive, but drops negative again on Monday. With apogee, when the Moon is at its furthest point from Earth, occurring yesterday, Saturday 24 February, path losses are at their highest for the month this weekend. 144MHz sky noise is low all week.

Category: GB2RS Propagation News