Propagation News – 19 June 2016
This week saw some fantastic six metre propagation, with the band behaving more like 20m. Multi-hop sporadic E contacts were made across the Atlantic, as far west as Arizona and south to Texas.
Six metres is a band that can exhibit both VHF and HF qualities, although we’ll leave any further sporadic E discussion to the VHF section of this report.
As for the rest of HF, the scene has been dominated yet again by unsettled geomagnetic conditions. The Solar Dynamics Observatory’s extreme ultraviolet image on Thursday showed extensive coronal hole activity and the K-index was pushed to six late on Tuesday, 14 June and the early hours of Wednesday, the 15th. This activity had been predicted for last weekend, but the solar plasma arrived a couple of days later.
The solar flux index declined to 87 on Thursday. This week NOAA predicts the solar flux index will be the range 85-95, with unsettled geomagnetic conditions possible on Friday and next weekend.
Noon-time F2 layer maximum usable frequencies over a 3,000km path are hitting 18.2MHz at times, while 20 metres is remaining open during the night according to the Chilton Digisonde. But the real thrills are the continued sporadic E events on the upper HF bands, so make the most them.
VHF and up propagation news
The second half of last week produced some great openings as sporadic E developed along a major summer jet stream. With core speeds above 100 knots it affected much of the usual favoured locations for sporadic E over the continent. The southwesterly jet was disturbed as it crossed the Pyrenees and Alps, to give options around the compass for many stations.
There were also some notable transatlantic paths using the waving jet stream flow to the west to give the necessary stopping off points for multi-hop paths to the USA and Caribbean. There will still be some jet stream activity over Europe this week, but the flow will be weaker and therefore any sporadic E produced may be more fleeting; so not such a good week.
The prospects for tropo are marginal, with a weak ridge of high pressure to the west and a slack flow over the country. These patterns normally produce some limited tropo overnight and around dawn, but these are often short-lived, since in the summer the temperature inversion soon breaks down once the sun gets up. Keep an eye for GHz bands rain scatter if showers break out.
With the Moon at lowest declination on Tuesday and losses still high, EME will be poor this week with short moon windows, so maybe it’s time to look at some satellite operation.
Category: GB2RS Propagation News
