Propagation News – 20 October 2024
The past week has been characterised by a low geomagnetic Kp index and excellent conditions on HF, including the 10m band. With a solar flux index between 168 and 195, and a Kp index that never rose above four, conditions have been better than the previous week, which suffered from the bad effects of solar flares and coronal mass ejections.
This came as NASA, NOAA and the International Solar Cycle Prediction Panel announced that the Sun has reached its solar maximum period, which should continue for the next year.
The announcement was not unexpected, and the exact period of maximum activity won’t be known for some time. But it was a wake-up call for radio amateurs to get on the bands and make the most of the conditions!
NOAA anticipates additional solar and geomagnetic storms during the current solar maximum period and during the declining phase of the solar cycle.
The solar flux index fell from its 200-plus highs to be in the 160 to 195 range last week. But this was still more than enough to keep the ionosphere running. Maximum usable frequencies over a 3,000km path have been consistently over 28MHz during daylight, falling to around 11MHz overnight.
Next week, the Space Weather Prediction Centre thinks the solar flux index will rise into the 200s again, but we may also get some geomagnetic disturbances, namely on the 22nd and 23rd when the Kp index might rise to around four.
Meanwhile, October can be one of the best months for HF propagation with good 10m band openings to Australasia in the morning and North and South America in the afternoon.
VHF and up propagation news from G3YLA and G4BAO
The current unsettled spell of weather seems likely to continue into next week and is not atypical at this time of year. We should expect a more changeable pattern around the autumn as the main polar front jet stream migrates south across the UK into its winter state over the Mediterranean.
That said, there may well be some brief interludes when the extended region of high pressure across Europe influences conditions over the British Isles, more specifically the south-eastern corner.
This is shown by some models around midweek for potential tropo from south-eastern England into the continent or across the North Sea to northern Europe and southern Scandinavia.
The obvious mode to result from this unsettled weather will be rain scatter and it is probable that the GHz bands will enjoy this period of weather.
Meteor scatter in October has a few showers to maintain interest. The Orionids and the Taurids are both active during the coming week. In fact, the Orionids, associated with the comet Halley, peaks on Monday and Tuesday.
Just a final note about sporadic E, which is ‘out of season’. Remember that there are no zero sporadic E months and recent indications have tended to show the response of raised critical frequencies of the sporadic E layer occurring around the middle of the day on the propquest.co.uk NVIS graphs.
You may also see peaks earlier in the day around dawn, which is the peak time for meteor input. Beware, it is easy to get hooked on out-of-season sporadic E hunting!
For EME operators, Moon declination is positive and rising. Path losses are rising again after perigee on Thursday, the 17th. So, we have increasing peak Moon elevations and longer Moon windows until Tuesday, the 22nd. 144MHz sky noise is low to moderate for the rest of the week.
Category: GB2RS Propagation News
