Propagation News – 15 March 2015

| March 13, 2015

Last week we said that the sun’s surface was looking a little bare, but that was before sunspot region 2297 erupted. This new area has helped keep the solar flux index around 120-130, but has spawned a number of solar flares. This region has so far produced an X2.2 flare, along with four moderate M-class flares.

These had the effect of severely affecting the ionosphere on the sunlit side of the earth, causing massive absorption, especially on the lower HF bands. The Colorado Digisonde shows the X-class flare event on Wednesday 11th wiped its plots completely up to around 10MHz for about 30 minutes. At the time of writing no associated coronal mass ejection had hit the earth. Region 2297 will be with us for a while yet, so expect more flare activity and possible CMEs, which can have the effect of reducing maximum usable frequencies.

Looking ahead to next week, the solar flux index should remain around the 120 mark according to NOAA, with increasing risk of geomagnetic disturbances.

VHF and up propagation news

This week, the somewhat enhanced VHF/UHF conditions are likely to continue, especially at first, with a seasonally typical large high over Scandinavia extending a ridge across the British Isles and giving some lift conditions in most areas.

The Scandinavian high will slowly decline and propagation will become flatter again over the UK as a more unsettled weather type takes over from midweek; probably with an early ‘April showers’ flavour so there may be some daytime rain scatter options available from afternoon cumulonimbus clouds.

Some models do keep the tropo hope alive by rebuilding a new high from the south west temporarily. The (TEP) openings from southern Europe on 50MHz continue in the early evening so stations in the extreme south west of the UK should keep alert for any brief extensions northward.

Again, no meteor showers this week, so keep looking for random meteor scatter contacts on the lower bands in the early mornings. The Moon is at minimum declination today, so there will be short but increasing Moon windows for UK EME operators in the coming week with losses at a minimum Wednesday through Friday.

Overall, it’s a week of opportunity for the VHF/UHF/Microwave bands.

Category: GB2RS Propagation News