Propagation News – 3 April 2016

| April 1, 2016

This past week saw continued low to medium geomagnetic disturbances thanks to ongoing solar coronal holes. A geomagnetic storm watch has been issued for the 2nd of April due to a disturbed interplanetary magnetic field, coupled with elevated solar wind speeds from a coronal hole high speed stream. This could see the K index climb again to five or six. Periods of further, but less potent, geomagnetic storming are forecast for the rest of next week.

At the time of writing there was just one solitary sunspot, which is stable and non-threatening. The overall trend of declining sunspot and flare activity will gradually continue as we slowly make our way towards the next solar minimum around the end of the decade.
Next week, NOAA predicts the solar flux index will be in the mid 80s. As we are now in April you should be using a smoothed sunspot number of 39 for VOACAP-based prediction programs.

April remains a good month for north-south paths, such as UK to South Africa. We also have the continuing DXpeditions of VK0EK on Heard Island and FT4JA on Juan de Nova Island near Madagascar. The optimum bands to work FT4JA are likely to be 17 or 15m, with occasional openings up to 10m if the K index remains low.

It seems that we are stuck in this slightly unsettled April showers story for another week, with any high pressure displaced to the east and well away to the south-west of the British Isles.

So what does that leave for VHF/UHF operators? From a Tropo perspective, not a lot really, but we could again see some rain scatter options on the microwave bands from the large April shower cumulonimbus clouds. Lastly, it is worth another ‘heads up’ for the 2016 Sporadic-E season, which should be showing its hand on 10m during late April. Dust down those frequency lists, check the beacon portion of the band and give it a try. The 28MHz beacons are listed from page 135 to 140 of the 2016 RSGB Yearbook and, with more than 100 beacons per page, you’ll be spoilt for choice. There is also the prospect of some trans-equatorial propagation activity at this time of the year, making 10m a band well worth keeping an eye on during April.

There are no major meteor showers this week. In the run up to the Lyrids, from the 16th to the 22nd of April, there may be a small increase in random meteors towards the end of the week.

The moon will be close to the sun in the sky on the 7th, so EME degradation will be high due to sun noise. Additional path losses due to the moon’s perigee will be low for a few days either side of this.

And that’s all for this week from the propagation team.

Category: GB2RS Propagation News