Propagation News – 11 October 2020
We had another week without a single sunspot appearing on the solar surface. The only upside was that the solar wind was largely calm, which resulted in a settled ionosphere. The solar flux index remained pegged at 71 or 72, reminding us that although NASA says that Solar Cycle 25 has started, we are still a long way from the glory days of solar maximum. Having said that, on Thursday morning there were signs of some activity on the Sun’s south-eastern limb that may or may not result in a spot forming in due course.
There were numerous warnings this week for spacecraft operators about high levels of the 2MeV electron integral flux. This can result in charging occurring on satellite solar panels and other electronics. It can also have a detrimental impact on HF radio in the polar regions, while north-south paths remain relatively unaffected. However, after a brief geomagnetic disturbance when the Kp index rose to four on Monday, the 5th, conditions remained settled, with the Kp index mainly being one throughout the week. This no doubt helped the ionosphere, with numerous reports of 15 and even 10 metres opening up. This time of year usually supports north-south paths as witnessed by Adrian, G0KOM logging on 15m Cyril, FR4NT on Reunion Island in the Indian Ocean. An F2-layer opening also brought in Carlos, CX7CO in Uruguay on 28MHz CW, who was logged by Chris, G3SJJ.
An unseasonal sporadic E opening saw France and Italy being worked on 10 and 12 metres on Tuesday. So it is rather good news for HF at the moment, despite the lack of sunspots.
NOAA predicts more of the same next week with the solar flux index predicted to remain around 70. Geomagnetic conditions are also expected to remain settled with the Kp index at two or three.
VHF and up
Last Tuesday saw a surprise widespread sporadic E opening on 50MHz, with stations working into Italy and Spain. This was quite possibly a direct result of the current spate of meteor showers. We should always be alert to the unexpected, especially during very unsettled weather with strong jet streams and meteor showers in attendance. These are though, truly rare events.
It looks very much like another “bust” for the autumn season tropo mode this week. Low pressure will predominate and give another week of options to the microwave operators using rain scatter. A brief period with a ridge nearby is a slight possibility in the second half of the week, but not looking too strong at this range.
Next Sunday sees the peak of the Epsilon Geminids meteor shower. Not to be confused with the much bigger Geminids shower in mid-December, this one has a zenithal hourly rate of just three. Keep looking around local dawn for the best random meteors.
The Moon is at positive declination until Friday this week and path losses are falling as we approach perigee on Friday night. 144MHz sky noise is low this week until the Sun and Moon appear close in the sky on Friday lunchtime. As mentioned before, we are now well and truly into the period where perigee and lowest EME path losses begin to coincide with low declination and subsequent low peak moon elevation. This trend will not start to reverse until July 2022.
Category: GB2RS Propagation News
