Propagation News – 19 July 2020

| July 17, 2020

Last week a coronal mass ejection caught space weather experts by surprise, sending the Kp index up to four for around nine hours on Tuesday. The stream had a strong southward component in its Bz field, which meant it could more easily couple with the Earth’s magnetic field. The weak CME passage was enough to generate aurora at higher latitudes. Otherwise, the Sun was relatively quiet with zero sunspots and a solar flux index of 68-69 all week. Ten metre sporadic E has become less prevalent this week, with Thursday showing mostly weak openings to Mauritania, Spain, Sicily and Corsica.

Next week NOAA still predicts more of the same with a solar flux index of 68 and zero sunspots. There are signs of coronal holes on the Sun’s surface, which could result in unsettled geomagnetic conditions at times due to high-speed solar wind streams. The STEREO Ahead spacecraft’s extreme ultraviolet view shows signs of a hot spot on the Sun, which will rotate into view over the next week. This could be the precursor of a sunspot, but only time will tell. Meanwhile, daytime F2-layer maximum usable frequencies (MUFs) are still exceeding 20m, with occasional openings on 17m. Sporadic E openings still occur virtually daily with openings up to 10m. Night-time F-layer MUFs occasionally exceed 20m, especially up to around midnight.

VHF and up

This weekend we have developing high pressure over southern Britain, and it should provide some good tropo opportunities, especially across the Channel and over Biscay into Spain and down the west coast of Africa. It’s also worth noting that the Mediterranean is in full-on summer mode with strong ducts over the sea from most of the usual holiday destinations, for example EA6 to IS0. These tropo conditions should last into the middle of the week. After that, the models seem to suggest a return to more unsettled conditions as a front moves south bringing rain and heavy showers, some thundery, particularly in the south, and this weather type will last into the following weekend. So, there should be some strong rain scatter conditions on the GHz bands in the second half of the week.

There have been some very strong sporadic E events all the way up to 2m during the last week. The traditional components like jet streams make a strong showing on the upper air charts, so I would expect to see further sporadic E popping up next week, so check the bands mid-morning and early evening. With the Moon at peak declination today and path losses falling as we approach perigee next weekend, it’s a good week for EME. Although 144MHz sky noise is low all week, the exception is Monday afternoon when the Sun and Moon are close in the sky. There are no major meteor showers this week, so keep looking around local dawn for the best random contacts.

Category: GB2RS Propagation News