Propagation News – 18 February 2018

Sunspot group 2699 threw a surprise last week when it unleashed a C-class solar flare and a coronal mass ejection. While we have got used to having coronal hole activity, CMEs have been less prevalent over the last few months. The CME and a coronal hole solar wind stream were predicted to reach Earth by Thursday, 15 February. NOAA said the combined effects could generate minor, G1 class storming at higher latitudes, with a chance for isolated G2 storming as well, and issued an aurora alert for high latitudes.

The ACE spacecraft showed an increase in both solar wind density and speed from about 8am on Thursday, but ionospheric effects appeared minimal. But the full effects were seen later on Thursday evening when the K-index rose to four.

NOAA predicts that next week the solar flux index will fall back to around 70, due to a lack of new sunspots. Geomagnetic conditions may be unsettled at the beginning of the week due to the ongoing effects of the CME, but should be more settled later in the week. The maximum usable band over a 3,000km path still tends to be 17 metres, with occasional openings on 15 metres and higher.

Daytime critical frequencies are still around 5MHz, so 40 metres is still mostly closed to the UK during the day. Night time critical frequencies are mostly in the range 2-3MHz, so again 80 metres closes to UK contacts after dark.

VHF and up

The return of high pressure means that tropo will play a part this week. Conditions should be good across the southern half of Britain and well into the continent at times. Models show some hint that more disturbed weather could bring it to a close later next week.

There is some talk of a sudden stratospheric warming, which changes the stratospheric flow to look more like a summer pattern. There is a thought that this can lead to out of season sporadic E, and therefore well worth checking the clusters for activity on 28 and 50MHz.

You can keep an eye on digimodes activity on 50 and 144MHz by monitoring the operational frequencies for the different digital modes. Just use Google or look at posts on dxmaps.com to find these frequencies. This can act as a good real time guide for propagation, but remember to call CQ on the bands even if it seems quiet. If you don’t transmit, you won’t work the DX!

Moon declination goes positive this Monday and path losses will fall all week, as the Moon comes closer. This will give steadily improving EME conditions as the week progresses.

Category: GB2RS Propagation News