Propagation News – 6 March 2016
Solar activity was at lower levels this week. The Solar Flux Index declined to 91 on the 29th, before recovering toward the end of the week. However, it never quite reached 100.
Geomagnetic conditions were reasonably settled, with the A index in single figures and the K index hovering between one and three. This was mainly due to a lack of geo-effective coronal holes in the first half of the week, although at the time of writing this was unlikely to continue.
On Thursday a solar coronal hole on the sun’s equator was pointing directly at the Earth, threatening unsettled conditions as you are reading or hearing this report.
Next week, the solar flux index is predicted to be around 100 to 105. After an unsettled start, geomagnetic conditions may become quieter, which may lead to better HF conditions later in the week.
Conditions on the lower bands have been very good, with the Medium Wave Circle reporting good reception of signals from the USA. Forty metres has also been humming, with strong North American SSB signals appearing from around 2200 UTC.
HF has also been active with Andy, M0NKR reporting many contacts to the Caribbean on 20 to 12 metres. This was probably due to the more settled geomagnetic conditions rather than the lacklustre sunspot activity.
VHF and up propagation news
It will be another quiet week for VHF and UHF tropo-style propagation, with low pressure and a cold northerly wind this weekend. This will last into Monday before a ridge builds from the west. This ridge is probably not as good as it sounds, since it is building in fairly cold air and so not very useful for tropo. In any event, it may only provide temporary enhancement over southern Britain. A weak trough will bring a collapse of any lift midweek, but a further ridge of high pressure may restore slightly better conditions at times over the second half of the week.
The rare 50MHz sporadic-E opening on 24 February, as reported last week, seems to have been caused by a very sharp and moving jet stream trough moving across western Iberia. This fits in nicely with the wind shear theory of sporadic-E whereby turbulence caused in the jet stream can propagate upwards as gravity waves to cause wind shear in the E region.
We are still going down the slope of seasonal random meteor rates until the onset of the April Lyrids, so early morning continues to be best time for random meteor scatter operation.
The Moon’s declination goes positive on Wednesday night so the longer moon window, combined with perigee where losses are lowest, make it a good week for EME operation.
Category: GB2RS Propagation News
