Propagation News – 13 August 2017

| August 11, 2017

Last week, the solar flux index continued in the mid-70s, with a single sunspot group making its way across the visible disk. Compare and contrast this with the same week last year, when there were actually five sunspot groups visible. This confirms, as it we didn’t know, that Solar Cycle 24 continues to decline. The current estimates for sunspot minimum place it around 2019 to 2020, so get used to more of the same.

The good news last week was that conditions were more geomagnetically stable, with the K-index mostly around one after Monday, the 7th. This meant that there was DX to be had, including some short-lived openings to the Far East on 20 and 30 metres around 1800hrs. Milton, ZP9CTS in Paraguay was also worked by Tony, G4CJC on Tuesday using the new digital mode FT8 on 10 metres.

Next week may start off unsettled due to another solar coronal hole, which became Earth-facing on Wednesday. This suggests unsettled geomagnetic conditions could occur from Friday, the 11th, and run into this weekend. This could spark auroral conditions, but may ultimately result in depressed maximum useable frequencies.

Once the weekend is over, next week should be more settled and conditions may settle. Look for DX openings on 30, 20, and 17 metres, with occasional sporadic E openings on higher bands at times.

VHF and up

The big problem with multiple weather models is that they usually predict ridges of high pressure and troughs across the country at different times. It’s best therefore, to provide generalised operating guidance for the different weather types.

This week, the ridges of high pressure will tend to favour the south of the country for tropo, principally into the continent and across Biscay to Spain. The troughs and lows usually bring rain scatter and there’s been some good examples with the heavy thundery downpours lately. Look for heavy rain, shown as bright colours on the many online rainfall radars, to get the best from any large storm events.

The Perseids passed their peak at the weekend, but activity will still be high over the next few days for meteor scatter enthusiasts.

Sporadic E is still hanging on into the last part of the season with a few openings on most days, but not necessarily reachable from the UK. It’s quite likely that the unsettled weather currently bodes well for sporadic E, since the powerful upper atmosphere jet streams that drive the rainy weather are also good for sporadic E.

The lunar cycle continues on its predictable way. Now, and for the next few years, lowest path losses are coinciding with highest declination in the Northern Hemisphere. This means that Moon windows are longest when losses are at their lowest. This week should be good for EME, with falling losses as we move towards perigee and maximum declination on Friday.

Category: GB2RS Propagation News