Tag Archives: Ionosphere

The temporary impact of Allied bombs on the ionosphere

Many thanks to a number of SWLing Post contributors including, Mike, Dan, Ron and Bob who all shared this article from the BBC World Service:

The bombs used by Allied forces during World War II were so large, they weakened the Earth’s upper atmosphere.

The air raids turned towns to rubble and ash, but now new research shows shockwaves could be felt up to 1,000 km above the UK.

Chris Scott, from the University of Reading said: “I was absolutely astonished [when I found out].

“Each raid released the energy of at least 300 lightning strikes.”

It’s now hoped the research will give us a better understanding of how natural forces such as lightning, volcanic eruptions and earthquakes can affect Earth’s upper atmosphere.

[…]But Chris Scott admits “these were very temporary effects which heated the atmosphere very slightly.”

[…]Chris Scott said: “This [research] is really important if we’re going to understand the ionosphere as a whole.

“We know the ionosphere is controlled by solar activity but it varies much more than can currently be explained.”[…]

Click here to review the full article at the BBC World Service.

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NASA’s ionospheric experiment tonight and remembering The Woodpecker Project

The gas mixtures from NASA’s ionospheric experiment cause parts of the night sky to glow blue and green. (Photo: NASA)

Many thanks to SWLing Post contributor, Ed, who writes:

It might be interesting if you invited SWLing Post readers today see how NASA’s ionospheric experiment tonight (shortly after 9:00PM ET) affects RF propagation along the east coast:


I searched online to find any reference to this long series of NASA experiments affecting RF propagation, and found this 1980 paper:


…which contains this paragraph:

Ionospheric Modifications

The objectives motivating various experiments based on either decreasing or increasing the ambient plasma density by means of a chemical release include: (a) obtaining measurements of the rate of refilling after creation of a plasma depletion “hole” as a means of studying ambient ionization processes, (b) studying the magnetic field aligned propagation of VLF waves by creating a propagation duct, (c) simulating the formation and movement of the natural depletion “bubbles” which occur over the magnetic equator, (d) investigations of reaction rates, recombination coefficients, airglow production, etc., and (e) creating the conditions for inducing selected plasma instabilities to produce ionospheric irregularities and spread-F conditions. The science objectives in these experiments have a direct bearing on communication problems. Other forms of ionospheric modification are directed toward studying ionospheric/magnetospheric coupling and testing plasma theories.

So it might be fun to crowdsource from the SWL community to see if we can detect any propagation anomalies Tuesday night during this brief experiment. It’s unfortunate there’s not more time to coordinate different listeners monitoring different assigned frequencies. This reminds me of participating in ANARC’s “Woodpecker Project” in 1985 with 95 other SWL’s in 18 countries to determine the interference effects on HF broadcast from the Soviet Union’s use of Over-The-Horizon (OTH) radar in the HF bands.

I wonder how many SWL’ing Post readers participated in The Woodpecker Project and still have the nice “No Woodpeckers” tee shirt they earned for submitting their findings, which were combined into a final report that condemned the Soviets for causing interference on the HF bands.

Thanks for the tip, Ed! According to the linked article, the experiment will take place this evening, “soon after nine o’clock eastern time” (or 01:00 UTC).

This would be a great time to do an SDR wideband spectrum recording since you could possibly see any propagation effects on the waterfall display and play the event over multiple times. I’ve no clue if this experiment would yield any discernable results on HF, but it would be fun trying to detect it nonetheless.

Please comment if you plan to check out the experiment and/or if you were a participant in the Woodpecker Project!

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Air Force plans to decommission HAARP


HAARP (the High Frequency Active Auroral Research Program) in Alaska is now slated to be decommissioned as the US Air Force plans to “initiate divestiture in June 2014,” according to a USAF representative in this KTOO article.

HAARP was officially shut down in early May 2013–during a contractor “regime change“–but one of HAARP’s clients, DARPA (Defense Advanced Research Projects Agency), continued to use the facility for their research into 2014.

Unless someone steps up to pay HAARP’s expenses, the facility will be shut down.

Incidentally, HAARP has been the source of much speculation and conspiracy. A simple Google search for “HAARP” will reveal a number of theories.

Click here to read the full news article about the HAARP closure on KTOO.

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