Last week was a mixed bag as far as HF propagation is concerned. We had a solar
flux index that got as high as 83, but this was tempered by unsettled
geomagnetic conditions at times. The planetary K-index his four on Wednesday due
to incoming plasma from a large solar coronal hole. And it varied from between
zero and three for a lot of the week.
The good news is that there is
quite a large sunspot group in the north-west quadrant of the Sun that should be
pretty much Earth-facing by the time you read or hear this report. The bad news
is that there is another coronal hole rotating into position. While Sunday the
26th and Monday the 27th will merely be unsettled with a predicted K-index of
three, Tuesday the 28th and the rest of the week are predicted to be very
unsettled with a possible K-index of six. These unsettled conditions could
continue through to the end of the week.
At the moment we are seeing
maximum daytime critical frequencies over the UK of about 6.6MHz. This means 40m
is largely useable for contacts beyond 100 kilometres and we have daytime
maximum useable frequencies exceeding 21MHz.
Looking on the bright side, next
week we enter into March and head towards the spring equinox. This can be a good
time for the higher HF bands, with better conditions on north-south
paths.
VHF and up:
I hope you managed to keep all the antennas
intact and storm Doris passed uneventfully. The unsettled weather will continue
through much of the coming week with no signs of any significant tropo to look
forward to.
There is one brief period on Sunday when mild, windy and
cloudy weather may give suitable conditions for a slight lift, in the region
between a warm front and cold front. Given the speed that the weather systems
are moving, it will be a short visit and soon gone. That leaves us with
slow-moving low pressure nearby, but without large shower clouds at this time of
year, GHz bands rain scatter will be limited.
There are no major meteor
showers this week, but remember that the best time for random meteor scatter
contacts is around dawn, when the Earth is rotating into the flux of meteoric
particles.
The Moon reaches perigee on Friday, and its declination goes
positive on Tuesday, so EME path losses are low and Moon windows will lengthen
as the week progresses.
It’s a good week for EME, apart from today and
Monday when the sun and moon are within a few degrees of each other giving high
solar noise, especially at VHF where antenna beam widths are wide.