Propagation News – 20 March 2022

Well, what a mixed week of solar activity we have just had. Last week, we forecast that we could expect unsettled geomagnetic conditions over the last weekend, but we didn’t expect to see the Kp index hit six.

Sunday the 13th saw ground-based magnetometers hit hard with at least 15 hours of unsettled conditions, when the Kp index fluctuated between five and six. This was caused by a full halo coronal mass ejection, or CME, that was observed coming off the Sun on Thursday the 10th. This had a strongly negative Bz component so more easily coupled with the Earth’s magnetic field.

The net result was a decline in MUFs, reports of visible aurora in Scotland and complaints about HF conditions with the ensuing G2 geomagnetic storm.

Saturday wasn’t too bad with lots of contacts being made during the early part of the Commonwealth Contest. Twenty metre contacts with the New Zealand ZL6HQ station were also possible from the UK, although signals were very fluttery. The short path to ZL goes through the North pole auroral zone so it is not surprising that the signals were affected, despite the Kp index being down to one, from five, during late morning.

The solar flux index held firm at 125 on Saturday, but was already declining and was down to 107 by Thursday.

So, after last weekend’s onslaught, what do we have in store for next week?

NOAA’s Space Weather Prediction Centre thinks that the solar flux will again decline, from a predicted 115 on Saturday down to 95 on Friday the 25th. The geomagnetic conditions prediction has the Kp index rising to four on Sunday, but it may then decline to two by Wednesday the 23rd. The risk of an Earth-facing coronal mass ejection seems to have declined with the decrease in solar activity. So, for once, it looks like a good thing!

VHF and up

High pressure will dominate the weather charts over the next week or more, centred a long way east over Poland and the Baltic, but with a strong ridge extending west towards the British Isles.

These large highs are usually associated with a marked temperature inversion and this is a good omen for extensive tropo. This works best if there is moisture below the inversion, so misty low cloud or fog will be a good indicator for better conditions.

When the forecast is for dry sunny weather, this usually means that the Tropo may not be so reliable. Paths across the North Sea to northern Europe and into the Baltic region are worth extra attention.

It’s a good time to get together a list of beacons from the region, either from the RSGB website or here, and check the various clusters for signs of activity.

We are nearly there for the Sporadic-E season, but not quite yet. Aurora and meteor scatter are still worth a look though.

The Moon will be waning throughout this week with lowest declination on Friday/Saturday. However, path loss is also at a minimum this week, so conditions should be good until the 23rd when the Moon moves into the noisier part of the sky, for several days.

The early part of the week should provide opportunities for stations with fixed or limited elevation adjustment, due to the low elevation of the moon.

Category: GB2RS Propagation News