Propagation News – 5 January 2025
We started the new year with a bang, or more precisely a Kp index of 8 and widespread visible aurora. This was caused by a partial halo coronal mass ejection, associated with an eruption in the Sun’s southeast quadrant on the 29 December.
The strong G3 to severe G4 geomagnetic storm peaked at about 1800UTC on the 1 January as the solar wind speed moved past Earth at just above 500 kilometres per second. It then subsided as the Bz component settled into a north-pointing position.
HF propagation suffered as a result with the maximum usable frequency down for the rest of the evening. By the morning of the 2 January, things had improved and maximum usable frequencies over a 3,000km path were back above 28MHz.
The solar flux index remained above 200, which no doubt helped, but we are in rocky times from a space weather point of view.
A large coronal hole became Earth-facing on Friday 3 January which will no doubt cause some geomagnetic disruption today, the 5 January, as the Kp index rises.
NOAA predicts the solar flux index may decline this week, possibly ending in the 160s to 170s. Geomagnetic conditions may also be in for a rough ride around the 10 and 11 Janaury when the Kp index is forecast to reach 4.
From a radio point of view, January is a peak time for low-band DXing. The nights are long and dark so make the most of the 160 and 80m bands. You may also get DX during the late afternoon on the 40m band.
During the daytime keep an eye on the 10m band, which may throw up the odd, interesting DX station while the solar flux index remains high.
VHF and up
To start the year the main feature is low pressure over the country but, in the depths of winter, it’s good to remember that snow and rain both provide scattering opportunities for the GHz bands.
There is a glimmer of tropo hope for the end of the coming week, around the 11 and 12 January, as high pressure builds over northern Britain. This will be a cold-air high which tends not to be the best for tropo, but it’s worth a look nonetheless.
The solar conditions provided an aurora on New Year’s Day with a brief index of 8 during the afternoon. With other disturbances possible, it is worth keeping up to date with solar conditions and prospects for geomagnetic storms on spaceweather.com This is one propagation mode where CW is so much easier to copy under the difficult conditions of aurora.
Meteor scatter propagation is driven by the Quadrantids in the first week of January. It peaks on the 4 January but spans the period up to the 12 January. This is a productive shower with an hourly rate of 120. Since it’s the last major excitement until the late April Lyrids, make the most of it before we’re reduced to chasing random meteor activity during the rest of winter.
We have previously mentioned the chance of out-of-season Sporadic-E propagation in mid-winter and we still have the next week to keep alert, especially in view of the Quadrantids adding fuel into the E region. The ionised trails of the meteors provide long-lived metallic ions, which is the material that gets focussed into Sporadic-E if we are lucky.
The Moon starts the weekend with a negative but rising declination, going positive today, the 5 January, so Moon windows continue to lengthen. Path losses are low with perigee on Wednesday. 144MHz sky noise is low all week.
Category: GB2RS Propagation News
