Propagation News – 24 July 2016

There was plenty of solar action this week. The solar flux index climbed to 108 on Thursday thanks to a slew of sunspots. Plus we had incoming plasma from a coronal mass ejection that sent the K-index up to five for nine hours in the early hours of Wednesday 20th. There have also been some M- and C-class solar flares to keep us on our toes.

Unfortunately, due to the time of year the increased solar flux didn’t really create enhanced HF propagation, with maximum useable frequencies still languishing around the 15MHz mark.

There has, however, been widespread sporadic E over the UK, which has helped short-skip contacts, even on 40 metres, at a time when the F layer critical frequency was only around 5MHz.

NOAA is predicting that the solar flux index will decline from around 90 at the start of next week to 70 by the end. This is presuming that new sunspots don’t appear.

Geomagnetic conditions will remain slightly unsettled with a K-index of two or three.

Our tip for best propagation this week is to wait until mid to late evening. By this time the harsh summer D layer absorption will be declining, leaving the 20m and possibly 17m bands open to DX.

VHF and up propagation

It’s looking like a week of high pressure nearby in the south, but it will be fairly weak and likely to weaken further after midweek.

Any tropo is more likely early in the week, especially down to the south across Biscay towards Spain and Portugal and on towards the Canaries.

The north is likely to be under the influence of low pressure, with showery weather likely to bring some rain scatter on the gigahertz bands and probably in the south later in the week as the high declines.

Sporadic E is still prevalent well into August, so plenty of time to check out activity on 10m, 6m, 4m and 2m for those fleeting QSOs with stations in Europe, or beyond.

However, sporadic E does fare better when there are active jet streams over Europe, and the next week is not quite so well blessed, with most of the activity being over Britain and Scandinavia; perhaps a bit too close for maximum benefit.

Moon declination goes positive again on Sunday so lengthening moon windows added to perigee and lowest path loss on Wednesday means a good week for EME.

The 28th and 29th of July brings the Delta Aquarids meteor shower, which lacks a sharp peak and favours the Southern Hemisphere and tropical latitudes in the North. Look for some meteor rate enhancements an hour or two before dawn.

Category: GB2RS Propagation News