Propagation News – 7 June 2020

Well, the excitement of sporadic E propagation continued last week. There were extensive openings on 20 to 10 metres, which resulted in very short-skip openings at times. Paul, GM4ULS in Perth reports working lots of G stations on the South Coast of England on 20 metres on Wednesday, and the skip ran as short as a QSO into Northampton. He said, “At about 1320UTC the short skip lengthened slightly, and I began to attract stations in France and Belgium.” This just goes to show that sporadic E can affect all the higher HF bands. It is often seen on ionogram plots as flat reflections from the E layer about 95-100km, and a critical frequency of more than 10MHz. It often blocks signals from reaching the F2 layer, leaving gaps in the critical frequency plots on propquest.co.uk.

There has also been some F2 layer propagation around. Paul, GM4ULS also worked Jim, E51JD in the South Pacific on 20 metres on Thursday at 0634UTC. Jim featured in last week’s report as well.

The promised active sunspot region that was supposed to rotate into Earth’s view last week didn’t amount to much, but another sunspot group, numbered 2765, has subsequently appeared. It is a sign that sunspot cycle 25 is starting to crank up. The solar X-rays from this cycle 25 spot appeared to be fairly stable on Thursday, but that could change.

Next week NOAA predicts the solar flux index will remain around 70. The Sun may also remain quite quiet geomagnetically due to a lack of coronal holes and NOAA has the Kp index pegged at two all week. Hopefully the sporadic E season will continue giving plenty of short-skip and multi-hop activity on HF.

VHF and up

The present shift of focus to unsettled weather has now taken place and from now, through next week, the general theme is for this showery weather type to remain with us. This will mean that rain scatter is a good mode of choice for the microwave bands. Make use of the various radar displays to see where the nearest reflecting storms might be.

Tropo will be a rarity during this period, although there are signs of high pressure to the north-west of Britain later next week and one model even suggests a new high forming over the country next weekend, but it’s at a long lead time and much could change before then.

Now on to sporadic E, which has produced stunning results recently. Although it’s taken a step back, as I write this on Wednesday, I’m sure other good days are out there for us during the next week, and there will be plenty of jet streams on the charts to provide the triggers. Check the bands mid-morning and late afternoon or early evening for signs of activity and you should catch most of the openings.

The Moon is at minimum declination this Sunday, the 7th, and the consequent Moon peak elevation is accompanied by very high 144MHz sky temperatures. Unfortunately, we are now entering a period of the lunar cycle where low path losses start to coincide with low declination. This continues to get worse until July 2022, when apogee, that’s highest loss, coincides with maximum declination. Perigee and highest declination don’t coincide again until May 2026.

June continues to be an active time for meteor scatter operations, and the daytime Areitids shower peaks this Sunday.

Category: GB2RS Propagation News