Propagation News – 16 July 2017

| July 14, 2017

Sunspot number 2665 caught NOAA by surprise last week. As we wrote in the last report it was only just rotating into view, but ultimately turned out to be very large indeed. It helped push the solar flux index up to 91 during the week, although it was the only sunspot group visible.

We got the geomagnetic prediction about right though with solar material from a coronal hole pushing the K-index up to five on Sunday the 9th. The unsettled conditions continued until midweek, but then started to calm down after that.

Otherwise, it was business as usual with the summer ionosphere as the upper bands struggled to open to F2 layer DX at times. Maximum usable frequencies were around 14 to 18MHz over a 3,000km path, although daytime summer D layer absorption meant that at times there was little DX to be heard.

Next week, NOAA has the solar flux index in the range 85-90 with the chance of unsettled geomagnetic conditions midweek due to coronal hole activity. So it looks as if this weekend may offer the best HF conditions.

As always, keep an eye on the 40, 30 and 20m bands in the early morning and late evening, as they may still bring the odd surprise. Sporadic E openings are still possible on HF, but not as prevalent as they were in May and June.

VHF and up

The start of the week is dominated by weak high pressure over southern Britain, but it may provide some temporary night-time and early dawn tropo. As midweek approaches, the models are keen to bring an area of thundery rain northwards from France into southern Britain, so rain scatter on the GHz bands is a good mode to look out for. The latter part of the week sees high pressure returning to bring the tropo back, so again look for overnight lifts or perhaps some DX to the south across Biscay to northern Spain.

It’s worth noting that in the high holiday season in the Mediterranean region, there is potential for tropo on most days pretty much from one end of the Med to the other, so pack that VHF handheld. These paths are so long that some of the QSOs may get labelled incorrectly as Es rather than tropo on the clusters. Usually tropo lasts for extended periods, whereas Es will be very transitory.

On the lower bands, some minor meteor showers are active around the end of July, but they don’t peak this coming week.

We still have some time to go with the sporadic E season and weak jet streams mean some options on 10m, even if the higher bands are not well supported.

Moon declination is positive and increasing this week and with falling losses as we approach another perigee on Friday, there’s a good week in prospect for EME.

Category: GB2RS Propagation News