[CQ-Contest] Long term ionospheric changes (was Magnetic North Pole Drunkard's Walk)

donovanf at starpower.net donovanf at starpower.net
Fri May 8 12:03:28 EDT 2020

Hi Ken, 

Of all the long term (more than one year) changes you listed, the 
solar cycle is by far the dominant change. Lets hope we see some 
energetic solar cycle 25 sunspots this year. None of the cycle 25 spots 
we've seen do far have been energetic enough to affect propagation. 


----- Original Message -----

From: ktfrog007 at aol.com 
To: donovanf at starpower.net, cq-contest at contesting.com 
Sent: Friday, May 8, 2020 2:29:35 PM 
Subject: Long term ionospheric changes (was Magnetic North Pole Drunkard's Walk) 

Hi Frank, 

Thanks for your reply. It and the article were interesting and informative. 

I did some cursory research last night on long term changes in the ionosphere. There were a number of articles, most of which provided only abstracts. 

Mainly they dealt with the E and F2 layers. Things which could affect them over time are: 

- Long term changes in solar cycles 

- Global warming effects, such as the differential expansion and contraction of atmospheric layers 

- Changes in ionospheric chemical composition (due to greenhouse gases) 

- Earth's geomagnetic changes (strength, location and orientation). 

The practical effects would be changes in the heights of the E and F2 layers and differences in their refractivity. 

I did not find is any discussion of changes in the distribution (i.e., mapping) of the F2 layer over the globe, but I'm sure it's been studied too in this regard. I'll have to look further. 

Any differences I've noticed since I was licensed in 1958 are anecdotal in my own mind and therefore not too reliable. 

Regardless of any geophysical changes, the biggest change in DXing over the years has been geopolitical. 


Ken, AB1J 

-----Original Message----- 
To: cq-contest at contesting.com 
Sent: Thu, May 7, 2020 10:54 pm 
Subject: Re: [CQ-Contest] Russian Beats Out Canada for Magnetic North ... For Now 

Hi Ken, 

BBC's article this week " Scientists explain magnetic pole's wanderings" 
has attracted the interest of many radio amateurs interested in ionospheric 


Unless you've studied geomagnetic physics you probably never learned 
-- or even heard -- that the Earth has three north poles. The BBC 
article describes the poles very well, but does not address the 
relationship between the poles and ionospheric propagation. 

The geographic north pole is where the Earth's rotation axis intersects 
the Earth's surface in the northern hemisphere. It affects ionospheric 
propagation because the orientation of Earth's tilted axis to the Sun varies 
with the seasons and determines our daylight/darkness cycles throughout 
the year. 

While the magnetic north pole -- the focus of the BBC article -- is important 
to navigation systems, it has no significance to ionospheric propagation. 
Most of us learned about the magnetic north pole when we learned how 
to use a compass, it is located in the northern hemisphere where the Earth's 
magnetic field lines are measured to be exactly perpendicular to the Earth's 
surface. I ts position has been drifting about 50-60 km per year for about the 
last forty years. 

The geomagnetic north pole -- only briefly described in the BBC article -- 
is very important to ionospheric propagation and many other aspects of 
the Earth's space environment. It is the intersection of the Earth's surface 
in the northern hemisphere and the axis of a bar magnet hypothetically 
placed at the center the Earth. It is very significant for ionospheric 
propagation because it determines the position of the geomagnetic field 
in the Earth's space environment including -- very importantly -- 
its ionosphere. The geomagnetic field very profoundly affects ionospheric 
propagation. The geomagnetic north pole drifts only about one km. per year, 
a tiny fraction of the movement of the magnetic north pole described in the 
BBC article. 


As an aside, while the magnetic north pole is drifting fairly rapidly, 
the magnetic south pole is drifting very little at all. 


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