Propagation News – 27 March 2022

We had a good week of HF propagation with moderate solar flux index numbers and generally quiet geomagnetic conditions. The KP index has not been above three, at least by Thursday when this was written. And the SFI has been hovering around the 100 mark, which was enough to stir 12 metres into action with occasional 10m openings.

A proton storm was detected earlier in the week, courtesy of the LASCO instrument on the SOHO spacecraft. This was as a result of a CME on the far side of the Sun, which was luckily not Earth directed.

We now have a sense of excitement as a new sunspot group is currently turning into an Earth-facing position. Active region 2975, along with a larger Earth-sized sunspot group, appears to be in a growth phase. Both regions will likely be a threat for at least minor C-Class or moderate M-class solar flares over the next week.

NOAA predicts the SFI may rise from 98 to perhaps 120 over the next seven days. Geomagnetic conditions are forecast to be unsettled around April 1st with a predicted Kp index of five. A coronal hole became Earth-facing on Thursday so there is also the chance of an elevated KP index and reduced MUFs over the weekend.

Finally, with the spring equinox here this is a good time for North-South paths on HF.  Higher-band contacts into South Africa and South America have been prevalent over the last week and should continue for a few weeks.

VHF and up

Through much of the coming week we will see the high pressure system dominating the weather charts and continuing to provide a chance of further Tropo paths on VHF and UHF.

In this case, the high pressure will, at times, be centred right over the country and when this happens the temperature inversion may be too close to the ground for longer distance Tropo since it is changes in the refractive index of the air across the inversion that makes Tropo work for RF waves.

To avoid problems near the high centre, it is usually better to look for paths around the side of a big high to get the best DX. There are some weather models that try to break down the high later in the week, so make the most of the better conditions when you can.

There are still signs of disturbed solar conditions, so there’s always a chance of some aurora to play with, or of course any random meteors may be worth a check, especially early morning.

There are reports of some strong Sporadic-E signals on 10m, so as we move into April it becomes a more regular item on the menu, say for 10m and perhaps 6m on digital modes.

Moon declination is increasing and goes positive again on Friday, so Moon windows and peak Moon elevation will increase. With perigee last Wednesday, path losses are low but increase as the week progresses.

144MHz Sky noise is low all week.

Category: GB2RS Propagation News