Propagation News – 15 January 2023

| January 13, 2023

It seems X-class solar flares appear like buses; you wait for ages and then three turn up at once! Over the last week, we have had X-class flares on the 7, 9 and 10 January.

The latest, at the time of writing, saw sunspot region 3186 rotate into view off the Sun’s northeast limb and produce an X1.0 solar flare at 2247UTC on the 10 January. It may have thrown some plasma into space in the form of a coronal mass ejection but, as it is not yet directly facing Earth, any associated coronal mass ejection was likely directed away from us.

Over the coming days it will become Earth-facing and more activity is expected, with sudden ionospheric disturbances and coronal mass ejections becoming the norm. If this does occur, expect the MUF to take a dive, perhaps only for 20 minutes to an hour, if X-ray radiation from a flare impacts us, and for a day or so if a coronal mass ejection hits us.

So, although we currently have an SFI in the 190s, it will be hit-and-miss as to whether HF propagation will be good or bad. The best advice is to monitor the bands and don’t be surprised if we have some fallow days if the Kp index rises.

Excitement is building as the 3Y0J Bouvet DXpedition team is on its way. At the time of writing, they had reached Cape Verde en route to the Falkland Islands. Then they have a long boat trip with departure estimated for 14 January. Depending on the weather, expect them to be operating from late January for 22 days. We’ll take a close look at HF propagation to Bouvet in a later GB2RS report.

Meanwhile, NOAA predicts that the solar flux index is unlikely to remain as high as it is. It says it may drop into the 150s, although its predictions haven’t been too accurate recently. Nevertheless, 150 is still admirable. Let’s hope that the Kp index stays low to give the best hope of DX on the upper HF bands.

VHF and up

The unsettled weather pattern remains in place for the coming week and the main changes concern a deeper low in the sequence being strong enough to bring a temporary burst of colder northerlies.

This seems possible later this weekend and early next week. In terms of propagation, it’s looking like rain- or snow-scatter for the GHz bands will be the more likely mode. There is a possibility of some high pressure to the south after mid-week, over France and Biscay, but only reachable from the southern fringes of the British Isles with very limited tropo options.

There has been some strong Sporadic-E showing on the Dourbes graphs on on occasions, but we are coming towards the end of the mid-winter Es window this week.

Random meteor scatter and aurora are both options this week. The minor Gamma-Ursae-Minorids meteor shower reaches a low maximum on 18 January. As usual, look to benefit from the pre-dawn peak of random meteors.

The Sun is very disturbed, so you’ll need to track the daily behaviour of the Kp index for aurora prospects. Ideally, it should be five or preferably higher for aurora.

The Moon reaches maximum negative declination this coming Thursday, and at perigee on Saturday, so EME path losses are low and Moon availability windows are short. 144MHz sky noise increases all week, peaking at over 2000 Kelvin on Thursday.

Category: GB2RS Propagation News