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Propagation News – 10 May 2020

RSGB
May 7, 2020

It was a case of more of the same HF-wise last week. Zero sunspots and no geomagnetic disturbances meant that conditions were average for this point in late spring. The good news is that the sporadic E season has now officially started, and it is living up to its name. That is, it is sporadic! Either there is good propagation or nothing! Openings on 10 metres have included multi-hop to the Caribbean, with Saint Lucia and Trinidad and Tobago being workable on FT8. Other more general sporadic E openings have favoured Spain and Portugal one day, and Bulgaria, Romania and Algeria on another.

Some amateurs have been heard to comment that the openings must mean that the new sunspot cycle has started. But this is not so. Sporadic E is a seasonal phenomenon not related to sunspots and, when this season finishes in late August or early September, we can probably expect the 10 metre band to go back to sleep. So the message is to get on 10 metres right now and work whatever you can while the sporadic E lasts!

Other than 10 metres, 40 metres continues to be a very workable band, with openings occurring during the day and into the evening. As we head towards summer, we can also expect 20m to stay open later, and even after sunset, due to the changing chemical make-up of the ionosphere.

Next week, NOAA is predicting more of the same, with a solar flux index of around 70 all week and settled geomagnetic conditions, with an average Kp index of two. But, as we know, conditions can change quite quickly and there is always the chance of a disturbed ionosphere due to an enhanced solar wind from coronal holes.

VHF and up:

We have a high pressure week coming up, but getting there involves some low pressure and unsettled weather for some areas. The present high that is over, and just to the east, of the country will decline and drift away, so any tropo will not last long. In addition to the showery weather over the south, a very marked cold front will move south across the country over this weekend, giving further opportunities for rain scatter.

Any following showers will not last long as a new high builds in cold air to the north-west of the country. This drifts south-east to be over the UK by Tuesday and edges east during the second half of the week. All this means that tropo should be the dominant mode, although it will take a while to develop a decent inversion, so it may be rather patchy in quality.

The sporadic E season is having the odd flicker of enthusiasm, but is obviously much better for digital modes than CW or SSB. Their time will come as the season builds. At the moment we seem to be transitioning from a broader period around the middle of the day to the more familiar two peaked distribution of late morning and late afternoon/early evening; it’s well worth keeping a check on the 10m and 6m beacons.

There are no significant meteor showers this week, so stick to the early mornings for the best random meteor scatter.

The Moon is at minimum declination on Monday so will be low in the sky. With increasing path losses and high 144MHz sky noise until Friday it’s a poor week for EME. (rsgb.org)

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