venerdì 20 maggio 2022

Propagation News – 22 May 2022

GB2RS News Team
May 20, 2022

Solar activity reached a new peak for this cycle this week, with the solar flux index hitting 180 on Thursday the 19th. This was partly down to the very large active region 3014, which is almost big enough to be seen with the naked eye, if suitable precautions are taken. To put this into perspective, the sunspot number is 147, which is higher than the estimated smoothed maximum prediction of 115 for Cycle 25.

Meanwhile, geomagnetic conditions have been favourable with the Kp index moving between one and three since Monday. This is all good news and is being reflected in the band conditions at the moment, with round-the-world echoes being heard on some DX signals.

Make the most of them as there is the ever-present threat of X-class solar flares to contend with. Two active regions, which have already been emitting X-class flares, are about to rotate into view.

The USAF predicts that the SFI may stay above 175 until at least Wednesday, before declining into the sub-150 range. This is at odds with the NOAA prediction, which never really thought that the SFI would get to 180 last week. In other words, it is anyone’s guess what we will get!

Don’t forget that Sporadic-E is also livening up the upper HF bands and providing strong short-skip signals. These can often link into multi-hop Es or join with F2-layer hops to give surprise long-distance DX that is hard to predict.

We have never had it so good for some time and let’s hope it continues into the Autumn when HF can really come into its own.

VHF and up:

It seems we are in a typical summer unsettled pattern with areas of thundery rain and heavy showers drifting north from France. This will obviously keep rain scatter as an option.

Summer can also be a time of strong Tropo, especially around coasts and over the adjacent seas. This is because a strong temperature inversion can develop over cool seas with areas of mist and fog at sea level overlain by warm dry air blowing off the continent. These paths are likely to persist over long periods, particularly across the North Sea, English Channel and Irish sea with extended options south across Biscay.

To finish off we have the early stirrings of the 2022 Sporadic-E season, which is starting to show some promising signs, and not just on digital modes. A major controlling influence is often associated with the presence of jet streams nearby and the upper air forecast charts suggest that there should be some reasonable opportunities during the coming week. Don’t forget that jet stream upper air charts are available daily with commentary on the website.

There is no major meteor shower this week, but we are at the tail end of the Eta Aquarids shower, which began in late April and is generally regarded as petering out next weekend. Eta Aquarids is associated with Halley’s Comet. But don’t expect to see the comet until 2061!

The Moon will be waning throughout this week with decreasing declination and increasing distance as it moves towards apogee and that, therefore, leading to increasing path loss. Moon libration will be low.

This week’s TK/HB9CRQ Corsican EME microwave DXpedition should enjoy favourable lunar path conditions if the weather cooperates. (