Propagation News – 19 April 2020

| April 17, 2020

Last week we said that we expected the Kp index to rise over the weekend due to incoming solar particles from an Earth-facing coronal hole. But we did warn that it was impossible to tell how severe it might be. In the end it didn’t amount to much, as although the stream was travelling at up to 450km per second, its density was actually quite low and the Kp index topped out at a fairly low three.

The Sun remained spotless all week and the solar flux index remained pegged below 70. The only good news was that we have begun to see signs of the impending sporadic E season, with one or two days showing short-skip openings on 10 metres into Germany and Spain, and a probable F2 layer or multi-hop sporadic E opening into Paraguay and Brazil on Thursday. We expect these to increase as we head towards May, so do keep an eye on 28MHz. The FT8 frequency of 28.074MHz will likely be the first to show signs of activity, but don’t rule out the CW and SSB parts of the band.

Next week NOAA has the solar flux index at or about 68-70. Conditions should remain settled until the 26th when the Kp index is predicted to rise to four, due to the return of a solar coronal hole. shows that the daytime critical frequency (F0F2) is often exceeding 4MHz, so 80m and perhaps 60m are still best for inter-UK contacts. Twenty metres still remains the optimum DX band during daylight, with occasional openings on 17 and even 15 metres at times. Ten metre propagation, when it occurs, is still likely to be via short-skip sporadic E, with very rare F2 openings bringing DX.

VHF and up

As high pressure tends to favour cooler areas at this time the year, it’s common to find highs over Scandinavia. Conversely, as the continent slowly warms, there is a tendency for low pressure to form, say, over France or Biscay. That is pretty much the typical pattern we find through next week. What this means for propagation is that the southern half of the country starts with showery rain or thunderstorms and the prospect of some rain scatter. This rain scatter option appears to last until about Tuesday.

Northern areas nearer the high over Shetland and Norway could see some tropo. This is because another typical feature of spring is that the North Sea is often covered by a layer of misty low cloud, and that makes good conditions for tropo. So, look for paths along the east coast from East Anglia to north-east Scotland or across the North Sea to Denmark and Germany. Most areas see some tropo benefit in the second half of the week.

We are heading rapidly towards May, the nominal start of the sporadic E season. The position of the jet stream’s upper air patterns suggest that paths towards Spain and Portugal are more favoured, especially at first, with a second option of paths towards Scandinavia.

Wednesday sees the peak of the ongoing Lyrids meteor so look out for increased meteor scatter activity this week. Moon declination goes positive on Tuesday but with apogee on Tuesday, EME path losses are at their highest this week. 144MHz sky noise is low.

Category: GB2RS Propagation News