venerdì 17 giugno 2022

Propagation News – 19 June 2022

We said that last week’s relatively low solar flux index wouldn’t last very long and it looks like we were right. This week we have had an SFI that started at 121 and just kept climbing, peaking at 149 on the 15 June. Unfortunately, we have also had some plasma to contend with thanks to the combined effects of a coronal hole high-speed stream, along with a bright coronal mass ejection observed on Monday. These pushed the Kp index to five on Wednesday 15 June.

Luckily a long-duration eruption, LDE, measuring M3.4 detected around active region 3030 on Monday was directed away from Earth and missed us completely. But it does show that we can expect more in the way of CMEs as we head towards the peak of solar cycle 25.

F2-layer MUFs over a 3,000km path have regularly exceeded 21MHz and often 24MHz. There have also been some occasional 10m F2-layer openings, with Sporadic-E and multi-hop Es events as other likely modes of propagation. As a result, there have been many reports of DX being worked, including Vasco, 7Q7CT in Malawi and Harald, 9X2AW in Rwanda on 10-metre FT8.

The USAF predicts that the SFI will be around 136 this Sunday, falling back to 100 as the week wears on.

Geomagnetic conditions are predicted to be unsettled around the 24 June, although we could be in for a rough ride overall next week due to any unexpected CME from one of the numerous sunspots that have been flaring recently.

VHF and up:

We ended last week with high pressure nearby for southern Britain with a low-pressure north of Scotland pushing a cold front south. So Tropo in southern areas is getting displaced as the pattern becomes more unsettled and after some very high temperatures.

The bulk of the coming week sees high pressure off to the west and a cooler north-westerly flow over the country with some showery periods too. This presents the prospect of rain scatter, but somewhat limited Tropo conditions, chiefly for western-most parts and Ireland down to Biscay and Spain.

The Sporadic-E season is in full swing, although in the last week conditions have not been quite so exciting, apart from the magnificent opening to the States last Sunday evening. Widespread activity as far as Mexico and Texas doesn’t happen often and plots of the weather patterns showed that there were multiple jet stream areas of activity to make up the required sequence of four or five hops of Es.

Since the weather pattern driving this was not exceptional, it suggests that it could happen again, so perhaps keep the notion of checking 6m as late as mid-evening 2000-2200UTC in your back pocket during the rest of the month.

There are still plenty of meteor showers to fill in between the Sporadic-E in June. The Aretids, Zeta-Perseids, Beta-Taurids and June Bootids are all active this week. The latter is generally low activity, but it produced unexpected activity in 1998 with a ZHR up to 100 for more than half a day and in 2004 with a ZHR up to 50 over a similar period.

Moon declination goes positive again on Wednesday, and we are past this month’s perigee, so increasing Moon availability and increasing path losses is the story for EME enthusiasts this week. 144MHz sky noise is low, not exceeding 300 Kelvin until Thursday. (