Last week saw more settled geomagnetic conditions and, although there were few
sunspots, the ionosphere was able to offer DX contacts. The CQ Worldwide Contest
saw 15 metres and even 10 metres providing openings at times. With the solar
flux in the low 70s it was the seasonal upturn, due to change in ionospheric
chemistry, that was mostly responsible for the better conditions.
There
is also evidence that coronal hole activity may be responsible for an increase
in the ionospheric electron count. This shouldn’t be confused with the effects
of a coronal mass ejection, when the Earth is effectively blasted with a
high-speed solar wind, which can lower ionization levels and depress maximum
usable frequencies.
NOAA issues what are called ALTEF3 warnings when
energetic electron levels exceed a certain event threshold. HF propagation
enthusiasts might want to experiment and see if these coincide with higher
maximum usable frequencies and openings when the solar flux index remains
otherwise low.
Solar activity is predicted to remain at very low levels
next week with no visible Earth-facing sunspots at the time of writing. However,
another coronal hole will become geoeffective and NOAA predicts that its effects
could see the K-index rise to five or even six from Tuesday the 7th to Friday
the 11th.
Look out for the possibility of initial ionospheric
enhancements, but also the likelihood of unsettled conditions and depressed
maximum usable frequencies thereafter. However, an increased solar wind can
often bring unpredictable ionospheric effects, so do check the upper HF bands
for openings all week and keep an eye on the live ionosonde data
at propquest.co.uk.
VHF and up:
The enhanced tropo of last week
saw some good VHF and microwave bands DX, but it will decline quickly as a cold
front moves south and destroys the subsidence inversion. This weekend has a
colder northerly flow controlling the weather. This means strong shower
development around the coasts, especially of Scotland, Northern Ireland and
eastern England.
These showers are driven by the warmth of the
surrounding seas, whose temperatures change little from day to night. This can
provide a 24-hour run of potential rain scatter on the microwave bands. You can
track the showers on any rainfall radar to get the beam headings you
need.
The next item for attention could well be the return of high
pressure in the south late in the week, but this is not supported by all weather
models, so check the charts after midweek for signs of a ridge building from the
Azores high towards Biscay and southern UK.
The Moon reaches perigee on
Monday and maximum declination on Wednesday. This brings low losses and long
moon windows for EME, coinciding with microwave bands activity from Cape Verde
this weekend until Tuesday.
There are no significant meteor
showers this week, but the big Leonids shower is less than two weeks away, so
focus on checking all your systems. You can continue to look around dawn for the
best chance of QSOs via random meteor scatter.
