Propagation News – 16 July 2023
Last week saw the arrival of one of the biggest sunspots of this cycle. Active region 3363 could swallow the Earth four times over. It is a source of M-class flares, but at the time of writing hasn’t produced any X-class events.
A new sunspot region 3372 has just rotated into view and has also been the source of eight M-class flares, one of which may have caused a coronal mass ejection that could give a glancing blow to the Earth this weekend – watch this one for more activity as it rotates into an Earth-facing position.
Meanwhile, the Solar Flux Index has been hovering around the 200 mark, meaning daytime MUFs over a 3,000km path are around 21MHz, sometimes slightly lower. At night this falls to around 14 to 18MHz so don’t write off HF once the sun sets.
Next week, NOAA’s Space Weather Prediction Centre has the Solar Flux Index around 175. While we have been lucky that Earth has not been subjected to too much geomagnetic disruption, after any disturbance across the weekend, the Space Weather Prediction Centre has forecast that the Kp index will be around two again all week.
So it may be ideal for DX, like Silvano 9Q1AA/9Q1ZZ in the Democratic Republic of the Congo, who has been active on the 10 and 15m bands recently. Or the KH8RRC DXpedition to American Samoa which is active until the 18 July.
Remember, there is DX to be worked – you’ve just got to pick the right band and time.
VHF and up
The predominant theme this week is driven by low pressure systems, meaning further days of heavy rain or thundery showers and a distinct lack of Tropo from areas of high pressure.
However, there is a split in the different models’ view for southern Britain later in the coming week in which some try to build a ridge across southern UK and France from the Azores high. Check the forecast charts from Wednesday onwards to see which version ‘wins’.
In the meantime, the heavy rain will continue the recent good run of rainscatter on the GHz bands.
Sporadic-E will probably continue to be a feature on most days somewhere in Europe. Last Wednesday night saw another good opening to Newfoundland.
Remember that there are plenty of online clusters and map plots showing where the focus of activity is located. Each day a blog is published on propquest.co.uk detailing the locations of likely Sporadic-E activity, based upon the positions of various weather features suspected of being responsible for the location of Sporadic-E patches.
The recent behaviour of the Sun has regularly affected the prospects for VHF propagation by interaction with the Earth’s magnetic field giving a high Kp index, above five, which can be a sign of auroral conditions.
A high Kp index is potentially a bad thing for Sporadic-E prospects, some operators suggesting that it is possible that solar flare activity may also be a negative influence on Sporadic-E. Meteor scatter prospects continue to improve due to two broad-peaked showers coming up later in the month.
This weekend sees maximum Moon declination but losses are high as we approach apogee next Thursday. 144MHz sky noise is moderate until Monday when the Sun is close to the Moon for the whole day’s pass, lasting until 9am on Tuesday. After this, sky noise is low for the rest of the week.
Category: GB2RS Propagation News
