Propagation News – 21 February 2021
Well, we’ve had another week with zero sunspots, but we did have a geomagnetic disturbance. This was caused by the frozen-in Bz magnetic field of the high-speed solar wind stream going very negative. This means it can couple more easily with the Earth’s magnetic field allowing plasma to flood in. At its peak, the stream’s speed was more than 450 kilometres per second and this pushed the Kp index to four on Tuesday the 16th.
Otherwise, the highlight of the week was probably the CQWW RTTY contest last weekend. Chris, G0DWV reports that conditions were not brilliant, but he did manage more than 1300 QSOs from his well-equipped station. Highlights included Wesley, N7US in Arizona on 80m at midnight and Peter, VK4ZP in Queensland, Australia on 20 metres at 1230hrs.
Winter Sporadic-E seems to be in decline now. We’ve only spotted Spain on 10 metres twice this week. So until the main 2021 Sporadic-E season starts again, in late April or early May, it looks like it will be F2 layer DX only on the upper HF bands.
Next week NOAA predicts the solar flux index will be in the range 71-76, so nothing to get too excited about. A recurrent, coronal hole high-speed stream with negative polarity is forecast for the 20th or 21st of February. This is from a large solar coronal hole on the Sun’s equator.
As the solar wind is predicted to have a south-facing Bz component we may expect the Kp index to react strongly. NOAA predicts the Kp index could rise to at least four, although on the coronal hole’s last rotation the Kp peaked at five on the 25th of January.
Look out for any potential pre-auroral opening on the higher HF bands as the solar wind speed increases. Otherwise, expect the maximum usable frequency to decrease as a geomagnetic storm commences.
At the time of writing the data feed from the Chilton ionosonde is not available on Propquest.co.uk, but just click to select data from the RAF Fairford or Dourbes Digisonde, refresh and all will be well.
VHF and up
This is probably a good week to increase your satellite square count as the weather charts suggest that the unsettled pattern will continue. There’s just the slightest hint of a developing high over southern Britain at the end of next week. Rain will produce the opportunity for GHz Bands rainscatter at times, and there will be some heavier showers in the mix. It’s possible there may be some hail and thunder in the heavier ones, which gives better quality for the scatter users. The Tropo prospects aren’t great, but at least there is a possibility at the end of next week into the near continent from southern areas.
As we said earlier, we are now in the dormant period for Sporadic-E, so unless it’s a rare digital mode QSO, things will probably remain quiet until we are into April for CW and SSB contacts.
Moon declination reaches maximum on Monday, so we have long moon visibility windows with high peak Moon elevation. Apogee was last week, so path losses continue to fall.
There are no major meteor showers until mid-March, so pre-dawn continues to be the best time for random meteor scatter contacts.
Category: GB2RS Propagation News
