Propagation News – 26 July 2020

We had quite a quiet week with the Sun with zero sunspots and a settled geomagnetic field. The solar wind speed was slow, between 280 and 330km per second, and its magnetic field was weak, with no significant negative deflections in its important north-south Bz direction. Therefore, the resultant geomagnetic activity was settled.

On the 21st a sunspot appeared around the Sun’s limb. Now classified as sunspot group 2767, on Thursday it contained one sunspot, but its simple uni-polar magnetic signature suggests it is non-threatening.

We do expect the Kp index to rise on Friday, the 24th, due to the arrival of a coronal hole high speed stream. Modest magnetic enhancement is also forecast for 25 July with the possible arrival of a slow CME from the 19th.

Expect a possible pre-aurora enhancement followed by the potential for suppressed maximum usable frequencies over the weekend and into early next week.

HF conditions have been generally lacklustre, but Laurie, G3UML reports that WH6FXL and WA6QDQ/KH6, both in Hawaii, were both quite readable signals on 20m SSB at 0800 on Wednesday. Tom, GM4FDM reports working two JAs on 17m using his newly-erected dipole. The 10m UK Net group on Facebook also reported an FT8 opening to Japan on Monday as well.

This just goes to show that you shouldn’t just write off the summer as being no good for DX.

Next week NOAA predicts the solar flux index will remain in the high 60s with the Kp index between two and three. This generally suggests that HF conditions will remain similar to last week. Expect sporadic E openings on 10 metres to continue, although not at the rate that we had earlier in the month.

VHF and up

A series of low-pressure systems passing close by northern Scotland and various fronts crossing the country mean that there are likely to be few opportunities for tropo this week. High pressure is displaced to the south over France so any tropo will be mostly likely from southern England into the continent or across Biscay to Spain. That brings rain scatter on the GHz bands onto the agenda for many regions of the UK at some time or other during the coming week.

Sporadic E still warrants a mention, but it is becoming more elusive as we move towards August. It’s not a ‘no chance’, but it will need some strategy for being in the right place at the right time. The best options will be to monitor 10m or 6m mid-morning and again late afternoon or early evening. Paths on FT8 will prove good indicators of which direction might deliver as the Es develops.

With the Moon declination negative and falling further as the week progresses, Moon visibility windows will shorten and peak elevation will be just 32 degrees this Sunday and falling, leading up to minimum declination a week from Sunday.

Perigee will be Saturday, 1 August, so path losses are now increasing. 144MHz sky noise peaks at 2,500 Kelvin on Friday, so low noise preamps won’t help you that day.

The Southern Delta Aquarids meteor shower has a broad peak from the 26th to the 31st with a Zenithal Hourly Rate of 25, so look for enhanced meteor scatter activity in the coming week. In Europe, the shower radiant is above the horizon at night or in the early mornings.

Category: GB2RS Propagation News