Propagation News – 11 October 2015

| October 9, 2015

The sun severely disrupted the HF bands again this week. A high-speed solar wind stream with a south-facing Bz magnetic component continued to interact strongly with the Earth’s geomagnetic field. Strong, G3 level geomagnetic storming was observed at high latitudes and the K index hit seven on Wednesday evening. There were long periods on Wednesday and Thursday where it sat stubbornly at five or more.

The net result was a very depleted F2 ionospheric layer. At noon on Wednesday the critical frequency as measured by the Chilton Ionosonde was just 3.7MHz, indicating a maximum usable frequency over a 3,000km path of only 15MHz.

The only good news is that this means these are good conditions to look for auroral propagation on the higher HF and VHF bands.
Further storming may remain possible during the next week due to ongoing coronal holes. Sky watchers should be alert for visible aurora displays once it is dark.

With the solar flux index at more than 130, if the geomagnetic storming decreases there is a chance of decent DX if and when the F2 layer recovers.

The autumn months of October and November are often a good time to expect Tropo lifts due to the presence of areas of high pressure at this time of the year. These can be slow moving and provide several days of enhanced conditions on VHF, UHF and microwave bands.

The indications are that we may have a large high over Scandinavia for most of the coming week, extending a ridge towards the UK and down past Spain to the Azores. This could again bring lift conditions to many parts of Britain, favouring E-W paths across the North Sea to southern Scandinavia and the Baltic states, with a secondary option southwards past western France to northwest Spain and the Canaries.

There is a possibility that the North Sea paths may not quite last to the end of the week though, as low pressure reaches northern Scandinavia by Friday. There are no major meteor showers this week, so continue to look for the best random meteor scatter QSO opportunities in the early mornings as the earth’s rotation and orbital path combine to sweep up the maximum number of meteoric particles.

The moon reaches apogee today and its declination goes negative, meaning shorter, but daylight, Moon windows with high losses in the coming week.

And that’s all from the propagation team for this week.

Category: GB2RS Propagation News