Propagation News – 11 July 2021

| July 9, 2021

As predicted, the solar flux index declined this week, ending at 76 on Thursday. This was due to the large sunspot regions 2835 and 2836 having rotated off the Earth-facing portion of the solar surface. But make a note to check the SFI around July 21 onwards when, hopefully, they will make a return.

The sunspots’ departure has left us back in the solar doldrums again with only a minute spot, region 2839, being visible. Luckily, geomagnetic conditions have been quite settled with a maximum planetary Kp index of three last week. This meant that the ionosphere could settle, and we could make the most of the lower levels of solar radiation.

Night owls scored this week with 20m openings to the western states reported around 0500-0600UTC. Laurie, G3UML also reports working central North America on 20m from about 4 to 6.30am. Note that these were CW and SSB contacts.

This year’s Sporadic E season also continues to delight UK amateurs. While the best DX has been on 6m, and not part of this report, 10m is still providing a lot of activity. Make the most of it – if you don’t, you’ll likely regret it!

Next week, NOAA’s Space Weather Prediction Centre says the SFI will be around 80. Geomagnetic conditions will be mainly quiet, although a large coronal hole reaching up to the solar equator is rotating into an Earth-facing position. This will be facing us around Saturday the 10th so look for possible unsettled geomagnetic conditions, with the possibility of depressed MUFs early next week.

VHF and up

The current weather pattern places the British Isles in an unsettled region with heavy showers, longer periods of rain and occasional frontal rain bands crossing the country. This is clearly useful for rain scatter on the GHz bands.

There are weak suggestions that there may be a return of high pressure close to southern areas in the second half of the coming week, but other models continue the unsettled theme, and it’s certainly not a given at the moment. Overall, it looks like Tropo is a possibility, but mainly in the south and perhaps only briefly.

That leaves Sporadic-E and, for this mode, there are some good pointers in that the main jet stream across the Atlantic is pointing right at northern Europe and this should be a reasonable orientation for Es from the UK into Europe at times. Of course, we ideally need many other elements to be right too, so as usual, the message is to check the bands, clusters and call CQ now and again.

Moon declination is positive and falling, going negative again on Friday, so Moon visibility windows will shorten. Path losses will continue to fall throughout the week.

There are no significant meteor showers until the end of the month, so continue to look around dawn for the best random meteor scatter opportunities.

Category: GB2RS Propagation News