Tuesday, March 7, 2017

F2 Opening on 28 MHz to Africa on Wed 1st March 2017

With the Solar Flux Index down around 75, the 10 metre band is more or less dead every day at the moment. It was a bit of a suprise on the 1st of March 2017 when signals from Africa appeared on the band.

The first signal I heard was TR8CA in Gabon on 28 MHz SSB and later on 29 MHz FM. This was followed soon after by S01WS in the Western Sahara who I worked on cw.

I could hear these stations working plenty of Europeans and Americans so it was obviously a good opening. When I saw TR8CA being spotted by LA and SM stations in Norway and Sweden, then I knew something really unusual was happening. I suspected some sort of pre-auroral enhancement and the RSGB news a few days later confirmed this...

We were pleased to get the HF propagation prediction pretty much spot on last week. While Monday and Tuesday were reasonably settled, Wednesday saw the effects of solar material from a large coronal hole as it hit the Earth. The K-index leapt to five around lunchtime and there were reports of HF openings up to 10 metres. This was probably a pre-auroral enhancement, but it didn’t last too long.

This is what the K index looked like just before and after the event...

As you can see, nice and low early on the 1st of March and then the K index climbs to 7.

As is common with these type of events, the HF bands were very poor in the following days with 18 MHz just about open. 21 MHz and 28 MHz were dead.

The map below shows TR8CA and S01WS in relation to my location.

S01WS in the Western Sahara was about 2,900kms and the ideal distance for one hop F2 propagation on 28 MHz. TR8CA at about 6000kms was probably 2 x F2 layer hops so it was an interesting one to hear.

The thing about the 10 metre band is that you can never be too sure when it will open. When the Solar Flux Index is down around 70-80, it should be closed but then events like this allow the band to open, especially on North-South paths.

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