Propagation news

Propagation news and other items:

First of all the spaceweather report, then scroll down for the RSGB's GB2RS weekly propagation report and other information.

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This page was updated 2017 September 14th  08:43  UTC.

The following data is from the Space Weather Prediction Centre:

Geophysical Alert Message wwv.txt

Issued 2017 September 14 0600 UTC

Solar-terrestrial indices for September 13 follow.

Solar flux 75 and estimated planetary A-index 15.
The estimated planetary K-index at 0600 UTC on 14 September was 2.

Space weather for the past 24 hours has been minor.
Solar radiation storms reaching the S1 level occurred.

Space weather for the next 24 hours is predicted to be minor.
Geomagnetic storms reaching the G1 level are likely.
Solar radiation storms reaching the S1 level are expected.

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Solar Region Summary (Sunspots visible on the solar disc)

Issued 2017 September 14 0030z

Regions with Sunspots.  Locations Valid at September 13/2400z

Region Number.........Location...........Area..........Mag Type

xxxx......................xxxxxx.............xxxx...........xxxx

2680.......................N09E26.............0120...........Alpha

Data courtesy of the Space Weather Prediction Centre

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Here is the GB2RS radio propagation report broadcast on Sunday, September 10th compiled by G0KYA, G3YLA and G4BAO on Friday 8th September, shown here by courtesy of the RSGB and their Propagation Studies Committee.

Last week the sun caught everyone out. While NOAA predicted the solar flux index would be in the mid 70s, the sudden appearance of a large number of sunspots pushed it up to 183 on Tuesday, although it had calmed down to 122 by Wednesday.

This had a major impact on the bands with openings up to 10 metres being reported.

To be fair to NOAA, these spots were only just appearing around the edge of the sun as last week’s report was being prepared.

Unfortunately, this new sunspot activity also resulted in numerous X-class solar flares, their associated coronal mass ejections and a proton storm. The K index was pushed up to five on Tuesday, and four on Wednesday and Thursday, impacting HF conditions adversely.

Next week the larger spots will have rotated off the sun’s visible surface, so the question is, what will follow them?

At the time of writing it looks like the Sun may calm down a little, although there is evidence of some new spots growing. NOAA predicts the solar flux index may decline into the 80s or 90s by the end of the week with unsettled geomagnetic conditions from around the 13th to the 17th.

The good news is that each week we edge closer to better autumnal HF propagation, so expect higher maximum usable frequencies and better DX.

October should be even better, so make sure your antennas are ready.

       

And now the VHF and up propagation news.

After last week’s class X9.3 solar flare, keep your beams to the North and look for any auroral propagation on six, four and two metres.

The big sunspot group will have rotated off the sun’s visible surface by now, but, as we said, it may not be the last one we see during this period.

The 2017 Sporadic E season struggled into the first week of September, but we sense we must be near the end now.

That leaves Tropo as the next best option for some DX at VHF.

Unfortunately, for much of the next week, the UK weather pattern is dominated by low pressure, bringing unsettled and windy weather - so that also looks like a non-runner.

Such changeable weather, often showery, may produce some rain scatter on the GHz bands, otherwise it's thin pickings for weather-related propagation modes.

With only minor meteor showers this week, continue to look around dawn for the best random meteor scatter contacts.

We have positive Moon declination all this week. So, combined with low losses as we approach perigee on Wednesday, it’s a good week for EME with long morning and daytime Moon windows.

And that’s all from the propagation team this week.

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Here is the GB2RS radio propagation report broadcast on Sunday, September 3rd compiled by G0KYA, G3YLA and G4BAO on Friday 1st September, shown here by courtesy of the RSGB and their Propagation Studies Committee.

Last week saw the solar flux index climb into the high 80s. Our prediction that the weekend’s ionosphere might be unsettled was partly correct, as the effects of a coronal hole pushed the K index to three on Sunday, but this quickly recovered.

We are now seeing a shift from predominantly summer ionospheric conditions to autumnal. As the ionosphere starts to cool it experiences a shift away from predominantly diatomic molecules to more monatomic species.

These are easier to ionise and, as a result, we can expect to see better conditions and potentially higher maximum usable frequencies as we move into September and October.

Roger G3LDI reports that 15 metres was open to the US on Wednesday afternoon, which bodes well for the future. And G0KYA’s tests with 5W and WSPR on 20 metres resulted in him being picked up in Alaska near sunset, which was also very positive.

Now the bad news. A very large coronal hole on the Sun threatens to push the K index high this weekend as a high speed solar wind impacts the Earth. This may result in noisy bands and suppressed MUFs, which could impact this weekend’s HF SSB Field Day operations.

NOAA predicts the solar flux index will be in the low to mid 70s next week. Once the coronal hole effects die away we may then get some more settled conditions. Either way, keep an eye on HF as you might be pleasantly surprised.

 

And now the VHF and up propagation news.

The end of the main Sporadic E season is approaching rapidly now and despite some six and four metre openings last Wednesday to Eastern Europe, such events will become much rarer in September.

Check the beacons on 10m and perhaps 6m, but in general it's back to meteor scatter for DX on the lower VHF bands now.

The prospects of Tropo should improve as we head into the quieter mellow days of autumn and high pressure becomes more commonplace. We should see a ridge of high pressure lasting until mid-week when the patterns flip to become dominated by low pressure.

This means that Tropo will be worth investigating at first and with the ridge extending over much of the country most parts of the UK will get something out of this period.

The changeover to low pressure-dominated weather patterns from mid-week is less useful, although if there are any significant spells of heavy rain or thundery showers, then rain scatter on the GHz bands is a possibility.

At this time of the year, very humid ex-tropical moisture from the States can become part of the train of low pressure systems that cross the Atlantic and make heavy rain more likely.

There are only minor meteor showers this week, so continue to look around dawn for the best random meteor scatter contacts

Moon declination is increasing again, going positive on Friday. Losses fall and Moon windows get later and longer as the week progresses, with the best operating times very late at night or early morning.

And that’s all from the propagation team this week.

 

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The GB2RS radio propagation report for broadcast on Sunday, August 27th

Now the radio propagation report, compiled by G0KYA, G3YLA and G4BAO on Friday 25th August.

Last week saw the solar flux index touch 90 as large sunspot group 2671 rotated into the centre of the solar surface.

But unfortunately the predicted unsettled geomagnetic conditions, caused by a high-speed coronal hole solar wind stream, pushed the K index up to six early in the week. This hampered DX by pushing maximum useable frequencies down.

The unsettled conditions continued until at least Wednesday 23rd.

Sporadic E did put in an appearance for last weekend’s International Lighthouse and Lightship Weekend, bringing short skip onto the 40m band.

This meant that many UK stations were able to contact special event stations on 7MHz that would have otherwise been unworkable, other than by ground wave.

This was a good example of how Sporadic E clouds over the UK can often bring advantages on the lower HF bands, such as 40, 30 and 20 MHz, when we normally associate Es with 28MHz and above.

This weekend there is a chance a small coronal hole may threaten us with more unsettled geomagnetic conditions. Conditions may also be unsettled mid week due to the effects of another coronal hole, but could improve for next weekend’s HF SSB Field Day.

Next week sunspot 2672 will be fully facing Earth. This has already produced an M-class solar flare and a number of lesser C-class flares, so we may be in for a bumpy ride.

NOAA predicts the Solar Flux Index will decline next week to the high 70s.

Maximum useable frequencies over a 3,000km path are still peaking around 17MHz during the day, with occasional DX openings on the 17m band.

 

And now the VHF and up propagation news.

For this week there is still a chance of limited Tropo options as a ridge of high pressure develops over southern Britain.

As usual for Tropo conditions it's the higher VHF/UHF/GHz bands that fare best and, unlike with Es, the openings can be long lasting, especially over sea paths.

Night-time is often best over the land, since there will sometimes be a shallow surface temperature inversion to add to the one brought by the high pressure, giving longer paths.

The second half of the week may see the return of low pressure in the north particularly, but it will increase the chances of some rain scatter on the GHz bands.

Sporadic E is nearing the end of its main season now and at the moment the jet streams look to be fairly weak, meaning Es will struggle to make many appearances.

As we head into the week, a new Atlantic jet stream will appear over Scotland and Scandinavia, giving a chance of northern Es paths into Scandinavia and across to the States.

About this time there will also be a broad upper ridge over France and Germany, which can also help with Es.

Only minor meteor showers this week so continue to look around dawn for the best random meteor scatter contacts

We have negative Moon declination this week and apogee on Wednesday.

The moon doesn’t get above 20 degrees elevation after Monday and path losses will be high. For VHF operation the low moon elevation means high ground noise in the beam of the antenna.

And that’s all from the propagation team this week.

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Here is a link to a YouTube video showing some of the work of the SWPC: https://www.youtube.com/watch?list=UU9hQvMjzSxurMirYDgOMezw&v=JncTCE2NWgc

 

GB3WES beacon 5,290 kHz.

 

StratWarm - stratospheric warming. Does it have an effect on HF propagatiion? If it creates turbulence in the ionosphere and stirs the electron distribution, then surely it does.

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