Propagation News – 15 December 2024
We had another week with quiet geomagnetic conditions. Other than a three-hour period with a Kp of four on the 9 December, as of last Thursday when this report was being compiled it had been below three for the past seven days.
Active region 3920 produced an impulsive M2.8 solar flare, peaking at 1006UTC on the 11 December. A quick M2.0 flare was also detected around AR3922 in the southeast quadrant. There was also an M6.4 solar flare at 0648UTC on the 10 December, but no Earth-directed coronal mass ejections were observed.
The solar flux index, despite being predicted to reach 200 again, has been simmering away in the 160s and 170s. Nevertheless, the quieter geomagnetic conditions have helped HF with the extrapolated MUF over a 3,000km path often hitting 40MHz at times.
However, the early sunset, which is around 1538UTC to 1621UTC at the moment depending on your location in the UK, means that the MUF drops off quite quickly in the afternoon. The average critical frequency at night is currently about 3.0-3.5MHz, which explains why the HF bands appear to be dead. The winter solstice is on the 21 December, and we won’t see much change until we get to mid-January.
There is DX to be had with CDXC members reporting working YJ0CA (Vanuatu) on 15 metres, V73WE (Marshall Islands) on 30 metres and YI1QEA (Iraq) on 10 metres.
So, at the moment, make the most of the daytime DX and greyline openings, and reserve the evening for Top Band and perhaps 80 metres.
Next week, NOAA predicts that the solar flux index will remain around 170 to 175. The Kp index is expected to be around two or three, apart from the 19 December when it could reach four.
VHF and up
The period of enhanced Tropo activity will have faded away by this weekend as the high pressure slips away into Europe and declines. This allowed low pressure to regain control from last Friday through the current weekend.
There may be a chance of some rain scatter propagation on the GHz bands, although it doesn’t look like a particularly good example.
All is not lost for Tropo followers, since the next high drifts in from the Atlantic early next week. Southern UK will benefit the most with Tropo paths to France and across Biscay. This lasts until midweek, to be followed by a return of low pressure for the second half of the week and probably a better rain scatter option than this weekend.
The big Geminids meteor shower peaked yesterday, the 14 December, but will linger throughout the month. The radiant source rises late afternoon and sets the following lunchtime and is most favourably positioned late evening and early morning, pre-dawn.
Next, a consideration of aurora prospects, which are still a little enhanced by solar conditions. So, as usual, stay alert to an increasing Kp index above Kp=4 to keep in the game.
Finally, remember that the period of Christmas and early January is well known for producing random out-of-season Sporadic-E. It’s not possible to fine tune Es prospects this far ahead, but it wouldn’t hurt to monitor the f0Es traces on the www.propquest.co.uk website between now and mid-January.
The Moon’s declination is at maximum today, Sunday 15 December, and also on Monday, so expect long Moon windows with high peak elevations. Path losses are still low but rising, so it’s still a good week for EME. The 144MHz sky noise is moderate to low all week.
Category: GB2RS Propagation News
