venerdì 20 gennaio 2017

Propagation News – 22 January 2017

We saw a couple of sunspots last week, but they weren’t enough to make a major difference to HF propagation. This was due in part to a raised K-index, thanks to solar material from a recurrent coronal hole. NOAA released a geomagnetic storm warning for the 18th and 19th. The solar index remained in the high 70s, while the K-index hit four around mid week.

While many people are bemoaning the poor conditions, there are highlights. Seventeen metres is opening reliably to DX on many days with strong signals to the east during late morning and weak openings to the west in the afternoon. Andy, M0NKR also reports there have been some good 80m openings to the US and Canada in the early hours. Eighty metres was also good for inter-G work late afternoon on Thursday the 19th.

Next week, NOAA predicts that the poor geomagnetic conditions are likely to continue, with the K-index hitting four at times, although the 25th and 26th should be slightly more settled. The solar flux index will be in the range 77 to 80, so propagation is likely to be more of the same. We recommend concentrating on the lower bands, but don’t give up on HF as we may get occasional HF openings up to, perhaps, 18 or 21MHz at times—please don’t miss them!

VHF and up:

We have just finished another week with high pressure on the chart, and it has produced some enhanced tropo conditions at times. But this has been less than might be the case if there were some moisture in the lower layers of the atmosphere. The better areas have been the north-west where moisture from the Atlantic and Biscay has improved the contrast across the inversion and given better tropo.

So what of next week? The high is going to last for just a few more days, until midweek, when the next sequence of Atlantic lows and fronts will cross the country. This will bring windier weather and some rain and destroy any tropo-producing inversions from our resident high, which will collapse quickly. In summary, a good start to the week, but poor for VHF/UHF tropo later.

We are now in the winter meteor activity minimum, where zenithal hourly rates are low and there are no major showers, but there are still opportunities for random meteor scatter contacts around dawn.
The Moon is at apogee today and reaches minimum declination on Thursday, so we have maximum losses and short, low-elevation moon windows all week. This week would be a good one to look to the artificial satellites for your VHF DX contacts.