Propagation News – 6 June 2021
The Sun was pretty quiet over the last week, with few sunspots and a solar flux index in the mid-70s. From a peak of 82 on Sunday, the SFI declined to 75 on Thursday when there were just two small sunspot groups visible, regions 2827 and 2929.
As predicted, geomagnetic conditions have been mostly settled, with a maximum Kp index of three. The solar wind has buffeted Earth at times thanks to a string of small coronal holes on the solar surface.
As we head towards the summer solstice we are seeing the HF bands remain open later in the evening. This is due to changes in the chemical make-up of the ionosphere. The 20m band currently remains open to DX over a 3,000km path until nearly midnight. In fact, if we had a few more sunspots we could even see 14MHz open 24 hours a day at times.
The main mode of interest remains Sporadic-E, with daily inter-Europe openings and occasional multi-hop openings to further afield. Make the most of these in June as conditions can decline as the season progresses.
Next week NOAA predicts the solar flux index will be in the mid to high 70s again. It says that the Kp index should remain around two. We may expect disturbed geomagnetic conditions on Sunday and early next week due to a large coronal hole on the Sun’s equator that became Earth-facing on Friday.
VHF and up
It feels like a classic ‘summer combo’ this coming week, with periods where Tropo is the dominant mode as weak ridges of high pressure remain close by over the UK. Remember that the best conditions are often overnight and early morning, since during the day the solar heating of the ground destroys any surface temperature inversion. In addition, you will also find that Tropo paths exist across the surrounding seas throughout the 24 hours, so /P from the clifftop or beach sounds ideal.
Mixed in with this hesitant high-pressure theme are occasional periods of instability releasing heavy showers, possibly with thunder and lightning. This is good for some, because summer thunderclouds produce excellent prospects for GHz bands rain scatter.
Early June is prime time for Sporadic-E, and it’s been simmering nicely for a while now, so perhaps more of the same. In theory, all bands up to 144MHz come into play.
A point of observation regarding the jet stream patterns is that, perversely, they are not looking so favourable this coming week, which makes predicting paths very unwise. Check the daily blogs here to see how things are developing.
We start another lunar month with positive and increasing declination giving lengthening daytime visibility windows, but with apogee on Tuesday, EME path losses are at their highest.
June the 7th sees the peak of the Arietids meteor shower. It actually lasts from May 22 to July 2, and with a ZHR of 30 it is one of the two most intense daylight meteor showers of the year
Category: GB2RS Propagation News
