Propagation News – 31 March 2019

Last week the predicted increased Kp index from a coronal hole didn’t amount to much. The coronal mass ejection from the Sun a few days earlier wasn’t quite Earth-facing so we dodged the bullet. Other than that, conditions have been quite settled with a maximum Kp index of three caused by an enhanced solar wind. This was due to a co-rotating interaction region, or CIR, on the Sun, followed by the onset of an isolated, negative polarity coronal hole high speed stream. Elevated solar wind conditions are expected to continue until Friday 29th March, before declining.

The Sun has remained spotless after sunspot group number 2736 left the visible disk and looks set to continue. As we head into April. NOAA has the Sun remaining settled with a solar flux index at 70 and the Kp index sitting at two or three. This means reasonable radio conditions, just in time for the CQ SSB WPX contest this weekend. And don’t forget that if you don’t like contests there are always the WARC bands, although 17m may struggle to open at times.

And now the VHF and up propagation news.

It looks as though we continue into next week with high pressure dominating much of the country, especially south western areas. This should continue to provide some Tropo, but slowly becoming less noticeable as the week progresses. Various models show low pressure close to northern Scotland at times, so this region is less likely to benefit from any Tropo.

There is a possibility of a few sharp showers, particularly at the end of next week – it is April, after all! These can be good for rain scatter propagation on the GHz bands.

The Moon is at apogee today, its furthest point from the Earth, so EME path losses will start to fall. Declination is negative and goes positive again on Friday, so we’ll see Moon windows lengthening with rising moon elevations and decreasing path losses.

There’s still a while to wait before we see the return of Sporadic-E, so work on your antenna systems for when it restarts. Remember that Sporadic-E can be a great opportunity for VHFers to improve their Morse skills. Give your brain a workout while the rest of the world is staring at computer screens and clicking a mouse.

Finally, there’s always plenty of DX opportunities on the satellites. While we have our marvellous geostationary, QO-100, there are still the low orbit birds to challenge you.

Category: GB2RS Propagation News