venerdì 19 novembre 2021

Propagation News – 21 November 2021

GB2RS News Team
November 19, 2021

We had a week of lower sunspot activity, almost back to the days of sunspot minimum. The solar flux index ranged from 78 on Sunday 14th to 79 on Thursday 18th with a high of 80 on the 16th. So, nothing to write home about there. Geomagnetic conditions were mainly unsettled, with a maximum Kp index of four, mainly due to an enhanced solar wind from an expected coronal hole stream. There was a C-class solar flare event on the 13th, but this caused us little harm.

Despite the relatively low solar flux numbers the ionosphere has been quite respectable. Propquest shows that extrapolated MUFs over a 3,000km path have continued to exceed 28MHz around lunchtime and early afternoon. Next week NOAA’s space weather prediction centre has the SFI in the low to mid 80s with a maximum Kp index of two. It doesn’t seem to think that we will see a rise in sunspot numbers for at least another week.

Let’s hope that geomagnetic conditions remain settled for the CQ Worldwide CW contest next weekend, as this offers the best chance of DX even without higher sunspot numbers.

VHF and up:

This week is going to be one of weather contrasts, with a change to proper cold weather from midweek. We have seen some useful areas of high pressure giving some Tropo during the second half of the week just finishing.

This weekend a cold front will bring colder and more unsettled weather south across the country, but soon a new high will build in from the Atlantic for the beginning of next week, so perhaps a little Tropo again. It all changes midweek as a more active weather system moves south and will introduce very much colder air, with talk of wintry weather for some areas and strong northerly winds. This could mean some rain scatter conditions are possible, but overall fairly flat conditions otherwise.

With the Leonids meteor shower past its peak, all eyes will be on the upcoming Geminids, which start to build up from the beginning of December. With a ZHR of 120+ it’s a big one! Until then stick to the period around dawn for the best random meteor scatter conditions.

For EME enthusiasts, the Moon is at apogee today and reaches maximum declination on Tuesday so expect long Moon windows and high peak elevations reaching 64 degrees on the day. Path losses are also at maximum, getting lower as the week progresses. (