Propagation News – 31 July 2016

| July 29, 2016

This week we have been looking once again at a blank solar disk. The spotless sun offered a solar flux index of 72 on Thursday, just six points up from a typical solar minimum figure. Unfortunately, the bad news doesn’t stop there. There were poor geomagnetic conditions last weekend thanks to the effects of a coronal mass ejection.

And conditions worsened again on Thursday morning when the K-index hit four, due to incoming plasma from a coronal hole. The net effect has been a reduction in maximum useable frequencies and poor daytime HF conditions, thanks to D layer absorption.

Next week another solar coronal hole will rotate into position. This may mean poor geomagnetic conditions and an elevated K-index of up to five on Thursday 4th and Friday 5th.

As we are now entering August, you should really be using the smoothed sunspot number of 35 for your VOACAP-based prediction programs, although with the actual sunspot number being zero, predictions may be optimistic.

NOAA predicts the solar flux index will remain in the 70s this week, although sunspots can suddenly appear.

This weekend’s RSGB Islands On The Air contest may see 14MHz being the ‘money band’ during daylight hours, with 80m and 40m coming into their own at night. There may be occasional F layer openings on 15m and short-skip sporadic E openings throughout HF.

VHF and up propagation news

For much of next week there will be low pressure near northern Scotland with a showery weather pattern producing the possibility of rain scatter on the gigahertz bands. At times a weak ridge close to southern Britain may allow some limited tropo openings across sea paths to the Low Countries and south across Biscay.

There is still time in the 2016 sporadic E season for jet streams to make the turbulent gravity waves, which may be part of the formation process for Es.

The good news is that we have a weak jet stream over the British Isles and into northern Europe for much of next week. This will favour paths into the Baltic and probably towards Italy and Spain if the jet stream is a little to the south of the UK.

It is also worth looking for the occasional path to North America, since the jet stream covers much of the width of the Atlantic.

The beginning of August sees the Perseids Meteor shower building gradually to its August 11th and 12th peak. So don’t wait, you should see meteor scatter conditions improving throughout the coming month.

The Moon is at its highest declination today and losses are low so another good week for EME.

Category: GB2RS Propagation News