ARLA/CLUSTER: Sol sem manchas solares significa propagação mais desafiadora

[João Costa > CT1FBF]

No Sunspots means challenging propagation

Changes in the density and structure of the ionosphere affects the
transmission path at high frequencies and can even block HF radio
signals completely.

The ionosphere relies on Sunspot radiation – the more there are
usually the better the propagation. The solar cycle or solar magnetic
activity cycle is the periodic 11-year change in the Sun's activity
and appearance.

We are still in Solar Cycle 24 which is the 24th since 1755 when
extensive recording of it began. The present cycle started in December
2008. It reached a maximum in April 2014 with the smoothed sunspot
number only 116.4, the lowest in over a century Scientists can’t
explain the Sun’s bizarre behaviour, being divided between it being a
fluke or a sign of a deeper trend.

In 2017 there have been more than 100 days with no sunspots. The next
Cycle 25 is predicted to start by 2020 peaking about 2024-25 and
forecast to be another weak one.

Fonte: Wireless Institute of Australia