Ionosphere, Magnetosphere, Earth

I have had an interest in radio all of my life and things which affect the propagation of radio signals. One of the most significant things that affects the propagation of many radio frequencies is a portion of the Earth’s atmosphere known as the ionosphere which is an area high enough up that shorter wavelength ultraviolet and even shorter wavelength radiation strips electrons from atoms and the atmosphere is tenuous enough that they don’t immediately recombine.

I find it fascinating in ways that go beyond it’s effect on radio propagation. I’ve always had a fascination with the plasma state of matter. I had a particular fondness for arcs and sparks and things you could do with high voltage since my early teens that has not abated, though time to pursue that interest is hard to come by.

Plasma, doesn’t act the same way a normal gas does, the way charged particles interact with magnetic field lines produces an array of behaviors that at times seem organic. Anyone who has observed an auroral display will have some understanding of this. Even though I live at a latitude that is far enough south that strong auroral displays are relatively rare (just north of Seattle), I’ve seen them maybe half a dozen times here and every time I’ve seen them they’ve been different.

One display I saw consisted of a single narrow stream of light that went from the northwest to the southeast. It appeared white in color, it was a narrow concentrated beam that looked like a giant neon, or more properly argon, light across the sky, except that it wriggled about and was full of kinks and bends instead of being straight. It lasted about ten minutes then diffused and faded. I have seen many pictures of auroras, but never saw one like that.

Another one that I saw looked as if you had taken a point light source, shined it off of ocean waves, and projected it onto a giant screen in the sky, the waves moving like ocean waves in real time.

I’ve also seen the more typical displays, the green sheets, patches of red, but seeing it in real time, seeing the motion, gives it a whole different character than looking at a static photograph.

I’ve had the sense that something has been changing for a long time. I get this both from my experience with a hobby of radio and TV DX’ing, and from the aurora. I’ve lived in this area all of my 49 years, but almost all of those auroral displays I’ve seen on the last five years.

This last solar cycle was the most intense on record. That in part accounted for the frequency and intensity of displays recently. The solar cycle is something that historically does change from cycle to cycle. There are periods in history where there have been very few or no visible sunspots, and there have been periods of high solar activity. This last cycle was the most active on record; but at the same time there are other factors.

Cosmic rays also have been on the rise; nobody seems to know why but the average cosmic ray flux has been on the increase in recent years. This two is something that varies and all the factors are not well understood.

One additional factor; the Earth’s magnetic field has been weakening. My understanding is that it has weakened by approximate 50% over the past hundred years. The Earth experiences periodic reversal of the magnetic poles (this is not the same as a physical pole shift, nor has it been associated with mass extinctions or high rates of mutation in the past). We may be headed into a magnetic pole shift; it’s really impossible to say until it happens because sometimes in the past the field has weakened, and then strengthened without reversing.

So we’ve got all these things happening, what does it mean to us? Recently, a study found that there is a correlation between cosmic rays reaching the Earth’s surface and cancer rates; the cancer rates are increased by increased cosmic radiation but there is a 25 year lag between the higher cosmic rays and higher cancer rates. So one thing it means to us is that as more cosmic rays bombard the Earth and more reach the Earth’ surface, 25 years later we’ll see increased cancer.

A greater danger is that to our satellites upon which we are dependent. There is a minor pole in the southern Pacific, that is a magnetic pole that is opposite in polarity to the main south pole, known as the southern Pacific anomaly. At times recently, this has become almost as strong as the main south pole. The Earth’s magnetic field tends to sweep up cosmic rays and particles from the Sun and direct them to enter the atmosphere at altitudes above the Arctic Circle.

On average, the latitude at which cosmic rays enter the atmosphere has decreased by seven degrees over the last 100 years. All of the above factors probably play some role.

I believe the following changes will occur as these changes continue:

We will experience more disruptions in long distance AC power transmission lines. A fix for this that would simultaneously upgrade transmission capacity making it possible to use higher mix of renewables would be to convert lines longer than 300km or so to DC transmission. Only long lines are subject to induction of low frequency currents that destroy transformers. Only the longer lines have significant AC power loses. And DC transmission becomes more economical than AC transmission on lines longer than 300km, so it makes sense to convert only these longer lines.

We will see a high failure rate of our satellites when they appear outside of the regions presently protected by the Earth’s magnetosphere. Already we are seeing this with satellites that go over the Southern Pacific anomaly. There are a number of steps we could take to partially mitigate this effect. We can rely more on terrestrial fiber optics and terrestrial wireless for communications. We can take steps to harden our satellites against radiation. This can include the use of special integrated circuits that have higher radiation tolerances, shielding, and equipping the satellite with it’s own magnetosphere in the form of strong superconductive magnets that deflect high energy charged particles. We can use more redundancy. One area that I feel will be particularly troublesome is the loss of global positioning satellites which we have become so dependent upon for navigation during a time when we also will not be able to depend upon a simple compass.

We will see weather anomalies caused by changes in high level cloud cover and by heating of the upper atmosphere. Cosmic rays entering the atmosphere leave an ionized trial in their wake that serve as a nucleus for condensation encouraging cloud formation. Cosmic rays can also significantly heat and expand the atmosphere. These effects will alter our weather in some ways that are hard to predict.

Radio propagation will be further impacted. We will see increased absorption at lower radio frequencies limiting the range of medium wave signals, increasing atmospheric noise at these frequencies, but higher shortwave frequencies will become usable and we will see the maximum usable frequency rise into the VHF bands more frequently. The highest I have ever seen the MUF rise to was around 200 Mhz, but I expect that we will see new record high MUF’s with noticeable defraction perhaps extending all the way into the visible light portion of the spectrum.

I believe we should be preparing for these changes by fortifying our energy supplies with renewables that we can utilize without causing further problems, so that we have the ability to adapt to changes that come our way.

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