Topband: the ionosphere in the sky

[Carl]

  Tom W8JI said

> The ionosphere in the sky is apparently different
> than an ionosphere on paper

That's a fair statement.

The ionosphere 'in the sky' varies quite a bit on a day-to-day basis. 
This day-to-day variation is due to solar radiation influences, solar 
wind influences, and neutral atmosphere influences. From what I've read, 
it appears that solar radiation influences are a small part of this 
total day-to-day variation - unfortunately this is the one we understand 
the best compared to the other two.

The ionosphere 'on paper' is a monthly median model, which is what is 
used in our propagation prediction software (VOACAP, W6ELProp, Proplab 
Pro, etc). It is statistical over a month's time frame. For example, we 
can say that 10m will be open on 17 days of the month to our target on a 
certain date at a certain time at a certain smoothed sunspot number. But 
we have a real tough time identifying which specific days of the month 
those will be.

Simply put, we do not have a daily model of the ionosphere. We can 
observe what's happening daily, but as of yet we can only statistically 
predict what's happening over a much longer time frame.

Carl K9LA