Propagation News – 4 December 2022

Last week was characterised by unsettled geomagnetic conditions that had not been forecast.

The Kp index fluctuated between three and five nearly all week, resulting in reduced HF propagation, especially over polar paths. The solar wind just refused to abate with speeds over 600km/s being commonplace. A southward-facing Bz interplanetary magnetic field just added to the problems.

In the CQ Worldwide CW contest last weekend, signals from the US west coast and mid-west were badly affected, with one station in Colorado sounding very fluttery and weak. Strong aurorae were also recorded in the polar regions.

Nevertheless, some good scores were made in the contest. It was a case of making do with what was available, HF propagation-wise!

By Thursday, the Fairford Digisonde was reporting F2-layer critical frequencies in the region of 10MHz, with an extrapolated MUF over 3,000km well above 28MHz around noon.

Sunspots remained on the decline all week with the solar flux index struggling to get to 110. But the good news is that could now all change. Solarham.net reports that the beginning of December 2022 will see a potential influx of sunspots.

A new active region is now beginning to turn into view off the south-east limb and was the source of a number of minor C-Flares on Wednesday.

In addition to this, old regions 3140, 3141 and 3145 from earlier in November 2022 are about to turn back into view from behind the north-east limb.

NOAA predicts the solar flux index could increase to 120-125 next week, which would be a welcome upturn. We may also be entering a more settled phase with regard to the Kp index too, with NOAA predicting a maximum index of two or three all week.

However, a solar coronal hole will become Earth-facing on Saturday, so we expect the Kp index to rise perhaps late Sunday or Monday.

The ionosonde data server in the US—for the Propquest foF2 graphs—is still having problems but is being worked on. In the meantime, you will see a backup plot from Fairford to keep things going.

VHF and up

The main weather theme for the coming week is that of colder north-easterly winds, but with some high pressure off the north-west to give a chance of slightly enhanced tropo, at first in western Britain. This will probably be spoiled in eastern areas by showers coming in from the North Sea.

GHz band rain-scatter options with the North Sea showers should be worth considering but, on this occasion, the showers may be relatively limited. So, don’t expect too much.

The solar conditions are still showing signs of activity, which can bring some VHF propagation options, such as aurora on 6m to 2m given a good trigger. So, look for high Kp indices above about five or six to make it worth checking.

Meteor scatter is, of course, an ever-present option for surprising us with any random activity. These sporadic meteors are more frequent around dawn, and the big Geminids shower in December 2022 is less than a fortnight away.

Moon declination is positive and increasing this week. So, Moon windows will lengthen and zenith angles will increase. Path losses are high and increasing this week. 144MHz sky noise is low to moderate, reaching 500 Kelvin next Friday.

Category: GB2RS Propagation News