Propagation News – 4 February 2024

We had another week of relatively calm geomagnetic conditions with a maximum Kp index of three. The solar flux index declined from 172 on the 24 January to 135 on the 30 January.

Nevertheless, that is still enough to support propagation on the 10m band, with the Maximum Useable Frequency over a 3,000km path generally being between 29 and 36MHz during daylight.

Solar activity has been at low levels with only minor C-class flares and one M-class flare detected. Active region 3559 is now located behind the west limb of the Sun and out of direct view. New active region 3567 in the northeast quadrant is showing the most promise as it appears to be in a growth phase. There is currently a 25% chance of a moderate M-class flare, according to the latest NOAA and SWPC update.

Earlier in the week, we had a period of moderate S2-level radiation storming. Proton levels streaming past Earth, following a solar flare early on Monday morning, increased but this has now declined.

A minor coronal hole also became Earth-facing on the 2 February, so we may still expect some disruption today, Sunday the 4 February.

The 10m band is still romping along, with beacons along the eastern seaboard of the USA coming alive in the afternoon. This weekend, the 3 and 4 February, sees the 10-10 International Winter SSB Contest, so there should be plenty of stations to work on 28MHz.

Next week, NOAA predicts that the solar flux index may rise again, perhaps to 150 today Sunday 4 February, and up to 165 a week later. We may have unsettled geomagnetic conditions on the 5 and 6 February, with the Kp index predicted to rise to three.

 VHF and up

This week, ending the 4 February, saw high pressure to the south of Britain and fronts over northern areas. For some stations in the southern half of the country, there could be useful Tropo conditions for the 432MHz Affiliated Societies Contest taking place today, the 4 February.

Unfortunately, the frontal activity over the north will move south on Tuesday to remove any chance of these better conditions lasting into the 144MHz UK Activity Contest on Tuesday 6 February.

The period from mid-week onwards looks dominated by low pressure with rain or showers and generally flat VHF and UHF prospects, unless you are set up for rain scatter. Other propagation modes like meteor scatter, aurora or Sporadic-E seem likely to remain in the background for the coming week.

For EME operators, moon declination is negative and falling to a minimum on Tuesday the 6 February. Path losses are also decreasing since their maximum at apogee on Monday 29 January. But with the low peak moon elevations, only eight degrees on Tuesday, moon windows will be short.

144MHz sky noise is moderate to very high all week going over 3100 Kelvin on Tuesday 6 February. Friday and Saturday see the moon and sun very close together, so Sun noise in antenna beam widths will be an issue.

Category: GB2RS Propagation News