Propagation News – 3 September 2023

We had another week of relatively settled solar conditions. The Kp Index never really got above three and the Solar Flux Index flattened to be below 140. Solar flares were nominal with only minor C-class events occurring and with no Earth-directed coronal mass ejections.

The solar wind speed remains low as does its density. The all-important Bz has headed south at times meaning it more easily couples to the Earth’s magnetic field, but the solar wind’s low speed and density means we have not suffered from geomagnetic disturbances.

As a result, ionospheric conditions were quite good with much DX romping in on 21MHz, including Mongolia on FT8 during the afternoon.

On the 10m band Vlad, 9Q2WX in the Democratic Republic of the Congo, and Robert, 9N7AA in Nepal, were both logged around lunchtime on CW. At the same time, Ravi, S79VU in the Seychelles could be heard on SSB.

The Chilton and Fairford Digisondes remain down, but Dourbes remains online which is still driving propquest.co.uk.

Daytime maximum useable frequencies over a 3,000km path are currently peaking above 28MHz at times, although you may find 21 and 24MHz more usable. Daytime critical frequencies remain above 7MHz making the 40m band very useful around the UK.

Next week, NOAA predicts that the Solar Flux Index will remain in the range of 140 to 156. Geomagnetic conditions are predicted to be quiet, apart from an excursion between September the 6th to the 8th when the Kp index could rise to three.

VHF and up

There will be some GHz bands rain scatter on offer as we end this current week, but it’s all change by the weekend. The prospects for VHF and UHF, then, are looking very promising indeed; especially good for those out working portable in the 144MHz Trophy Contest on Sunday, 3 September.

After lots of uncertainty in the forecast during the last week, there is now plenty of support from the models that the high-pressure version is the favoured outcome. This should be very encouraging for 2m band contesters hoping to get some enhanced tropo propagation.

Paths across the southern North Sea to Denmark and southern Sweden look good throughout. It would also be worth looking to the south across the Channel and, for some south-western parts of the UK, down across Biscay to Spain.

There are two very useful websites that detail the expected tropo prospects using the weather forecast model data to calculate the vertical changes in the refractive index of the air and hence tropo—these are dxinfocentre.com and tropo.f5len.org.

Remember that tropo improves as you move from HF to 2m, to 70cm and 23cm. So, give CW or SSB a try and don’t just stay on FT8 or overcrowded repeater channels during lift conditions. These enhanced tropo conditions will likely extend well into next week, but with a chance of low pressure bringing unsettled weather back to the south by the end of next week.

The daily sporadic E blogs have finished for this year, but the jet stream charts will still be available on propquest.co.uk, and of course random meteor scatter and chance aurora are still there if you are lucky.

For EME stations, Moon declination is positive again but reaches maximum late at night, initially moving to early morning as the week progresses. Last Wednesday’s perigee means path losses are still low but increasing daily. 144MHz sky noise is low, rising to moderate by next weekend.

Category: GB2RS Propagation News