Propagation News – 3 March 2024
Active region 3590, which was the large sunspot group that threatened us with solar flares and coronal mass ejections, or CMEs, has now moved to the Sun’s limb and is no longer a threat. Region 3590 was potentially dangerous, but ultimately wasn’t too bad.
Yes, we had flares, but they were only minor C-class and M-class events. Three recent CMEs, which will all probably miss Earth, but with a risk of some glancing influence, are most likely to have arrived by this weekend, ending 3 March.
However, old active region 3576 will begin to turn into view off the southeast limb by the end of today, 3 March.
The Kp index rose to 4.67 during one three-hour period on Tuesday 27 February, but the disturbance was short-lived and HF propagation wasn’t too badly affected.
Speaking of which, there have been some good HF openings to the Pacific area over the last week. Spotted have been 3D2AG in Fiji on the 17m band, VK on the 10m band, and the H40WA Temotu DXpedition to the Solomon Islands. This latter DXpedition has mostly been spotted on FT8 Fox and Hounds mode in the UK.
The maximum usable frequency, or MUF, over a 3,000km path still remains above 28MHz during daytime, with MUFs over 14 to 15MHz at night. So, as we head into March and towards the spring equinox, HF is still looking good.
Next week, NOAA predicts the solar flux index will be in the range 165 to 170. The Kp index is predicted to be two all week, but that is suspect and dependent on coronal mass ejections – or a lack of them. At this point in the cycle anything could happen. With six or seven active regions visible, the risk of a flare and CME remains relatively high.
VHF and up
The overall weather pattern remains very unsettled with further active lows and weather fronts crossing the country. There will also be periods with stronger winds and it may be cold enough for some wintry weather, especially over northern hills. The upshot of all this is that that Tropo will once again be a rarity, but rain scatter may offer some comfort to those on the GHz bands.
Later in the coming week, high pressure will strengthen over Norway and this will produce quite strong winds over the North Sea and eastern UK and perhaps encourage paths to the east, but it’s probably marginal at best in terms of Tropo.
The prospects for aurora and meteor scatter are not especially reliable, but it was encouraging to hear of some digital activity on the 6m band earlier in the week to South Africa and Lesotho. This was probably the result of Trans Equatorial Propagation or TEP, as suggested in last week’s news.
In fact, the spring period is a fairly good time to listen for TEP, timed between the decay of the southern hemisphere summer Sporadic-E season and the start of the northern hemisphere summer Sporadic-E season. It’s well worth checking for similar activity during March for paths to the southern hemisphere via TEP. Signals can be strong enough for SSB or CW modes, so it is not exclusively for digital modes.
For EME operators, Moon declination drops to a minimum on Tuesday. Path losses are past their peak now and falling until perigee on Sunday 10 March. 144MHz sky noise is moderate to high, reaching a peak of over 2,500 Kelvin on Tuesday 12 March.
Category: GB2RS Propagation News
