Propagation News – 27 March 2016

| March 24, 2016

This week has seen more settled geomagnetic conditions with the K-index hovering around two, although Wednesday saw it spike up to four due to a high speed solar wind stream from a coronal hole. Sunspot wise, the solar surface was a little lacklustre, with just one sunspot group visible. This pushed the solar flux index to the high eighties.

The current image from the Solar Dynamics Observatory spacecraft shows extensive coronal holes on both hemispheres. These don’t bode well for settled geomagnetic conditions over the next week.

The solar flux index is predicted to remain around 90. And although both NOAA and the US Air Force are predicting settled geomagnetic conditions, the SDO extreme ultraviolet image suggests otherwise. With a geo-effective coronal hole rotating into position on the sun we could get a geomagnetic storm before the end of the Easter weekend, with subsequent negative effects on the HF bands.

The goods news is that the VK0EK Heard Island DXpedition is under way. The best band and times to work them from the UK appear to be 15m from 0600 to 1400UTC, with potential 17 and 12m openings around the same time. There will be shorter openings on most of the bands at various times of day and night, so see the VK0EK website for more details.

VHF and up propagation news

Last week was poor for tropo despite some forecasts saying otherwise. And it looks like another poor week with low pressure dominating, especially over the north and east of the country. This means April showers-type weather is the most likely. Since these can often bring large towering cumulonimbus clouds with heavy rain, this provides some prospect of rain scatter on the GHz bands.

On the lower VHF bands, it’s not too long to wait now for the sporadic E season. There was one report last week on four metres, with the focus centred over the Apennine Mountains of central Italy. This was probably due to a jet stream being disturbed over the mountains.

Keep a lookout on 10 metres for the characteristic ‘short skip’ conditions as your early season indicators. The RSGB propagation forum will have a map of the jet stream locations each day to guide you where to look.

A week for EME system repairs is coming up as Moon declination is at its lowest on Wednesday, meaning only short, low elevation windows. The Moon is coming back towards us next week, but path losses are still high.

Category: GB2RS Propagation News