From the Naval Research Lab, not our normal fare, but interesting for its uniqueness.
The first global simulation study of equatorial spread F (ESF) bubble evolution using a comprehensive 3D ionosphere model, SAMI3, has been demonstrated. The model self-consistently solves for the neutral wind driven dynamo electric field and the gravity driven electric field associated with plasma bubbles.
Contour plot of the electron density as a function of magnetic local time (MLT) and altitude. A fully 3D spatial model of ESF describing the motion of ions along and transverse to the geomagnetic field in a narrow longitudinal wedge of the post-sunset ionosphere.
U.S. Naval Research Laboratory (2010) 
Developed by Dr. Joseph Huba and Dr. Glenn Joyce at the NRL Plasma Physics Division, SAMI3 is a fully three-dimensional model of the low- to mid-latitude ionosphere. SAMI3 has been modified recently to use a sun-fixed coordinate system to eliminate rotation of the dawn-dusk line and a high-resolution longitudinal grid to capture the evolution of equatorial plasma bubbles in the pre- to post-sunset sector.
The new modeling capability with SAMI3 has found that ESF can be triggered by pre-sunset ionospheric density perturbations and that an existing ESF plasma bubble can trigger a new bubble.
“Understanding and modeling ESF is important because of its impact on space weather,” said Dr. Joseph Huba, head of the Space Plasma Physics Section of the Beam Physics Branch. “ESF anomalies can cause radio wave scintillation that degrades communication and navigation systems and serves as the primary focus of the Air Force Communications/ Navigation Outage Forecast System.
Post-sunset ionospheric irregularities in the equatorial F-region were first observed in 1938 by terrestrial magnetism researchers, H.G. Booker and H.W. Wells at the Carnegie Institution of Washington. During that time, analysis of the scattering of radio waves by the F-region of the ionosphere at an equatorial location (Huancayo, Peru) revealed ESF is fundamentally a nighttime event, with greatest frequency of occurrence in the period from four hours before midnight to four hours after midnight.
“The ionosphere builds up after sunrise and reaches a maximum electron density in mid-afternoon, said Huba. “Subsequently, the ionosphere can be lifted to higher altitudes just after sunset because of the pre-reversal enhancement of the eastward electric field. During this time the ionosphere can become unstable.”
The F-region of the ionosphere is home to the F-layer, or Appleton layer, and is the densest part of the ionosphere as it extends from about 200 km to more than 500 km above the surface of Earth. Beyond this layer is the topside ionosphere. Here extreme ultraviolet solar radiation ionizes atomic oxygen. The F-layer consists of one layer at night, but during the day, a deformation often forms creating layers labeled F1 and F2 . The F-region is the region of the ionosphere that is very important for high-frequency (HF) radio wave propagation facilitating HF radio communications over long distances.
The upgraded version of SAMI3 represents a unique resource to investigate the physics of equatorial spread F, particularly the processes that control the day-to-day variability of ESFs. Future improvements to the current model include: modification to the geomagnetic field to have a tilt allowing the inclusion of longitudinal effects; coupling SAMI3 with a physics-based model of the thermosphere; and replacement of the full donor cell algorithm, currently being used for crossfield transport, with a high-order flux transport algorithm allowing for the capture of complex bubble evolution involving bifurcation.
Graecum est; non legitur
Is this phenomenon related to the Sudden Stratospheric Warming events that Bill Illis described at The Blackboard in 2009 after we’d just seen a spectacular SSW?
What effects if any do these Equatorial Spread F [?F-layer] bubbles have on the weather? Any ideas?
ah, is this the phenomenon Vukcevik illustrated a while back, interesting pic found also here? These plasma blobs track the geomagnetic equator more or less, but in parallel, on each side. They seem to have a resonance factor. Quite fascinating.
If this is right, you might like to add this picture to the article.
Speaking as a radio amateur who has been playing with the ionosphere for a fair few years now, this looks most interesting. If anyone from the Naval Research Lab reads this … any chance of a screensaver version? 😉
AleaJactaEst:
Timeo Danaos et dona ferentes!
Lucy, don’t see anything thing directly tied to climate off the top but I do see two curious things in that graph. One, look how the max is not at noon but at 2:30 to 3:00 just as maximum normal temperatures are hit on the ground. Must mean the disassociation of the oxygen must be accumulative and not instantaneous as I had always thought. I would have guessed noon.
And those cool ringing waves just after sunset, I have a long wire antenna hooked to an am radio in the garage that I can pick up New York, Atlanta from ok bounced from the ionosphere but I had always had wondered why you would get this thirty minute period of no signal, then thirty minutes of signal, back and forth until later in the night. Could that be exactly what this plot is showing in those waves? But that’s am frequency, not hf.
chris1958:
Unless it’s a bottle of ouzo.
Now that’s some real cool science Anthony, thanks. As I tell kids, you can learn your whole life and you will never run out of interesting things in this physical world!
Lucy Skywalker says:
January 19, 2011 at 1:15 am
What effects if any do these Equatorial Spread F [?F-layer] bubbles have on the weather? Any ideas?
NASA has concluded that there is a link between local weather and Ionosphere, but not sure which way. One possibility is:
http://www.vukcevic.talktalk.net/LFC20.htm
Do we now have a Green Flash predictor?
Do these plasma bubbles have any role in protecting the equatorial surface from harmful levels of solar radiation?
@WUWT
> The F-region of the ionosphere is home to the F-layer, or Appleton layer, and is
> the densest part of the ionosphere as it extends from about 200 km to
> more than 500 km above the surface of Earth.
Atmospheric density decreases with altitude, so the D- and E-layers, which are lower in altitude, are certainly more dense than the F-layer. Were you perhaps referring to electron density, which does peak around 300km I believe?
Slightly O/T but interesting is this 1933 article on the “Luxembourg Effect”. Radio Luxembourg had started broadcasting in that year on longwave (230kz) with a very powerful (for its time) transmitter, 150kw or so (eventually increased to 1.2 megawatts!).
This signal actually heated up (in the thermodynamic sense) the ionosphere, such that it modulated other radio signals broadcasting on entirely different frequencies. For example, Radio Lux’s programming could be heard on a relatively weak Swiss station monitored in England. The Swiss signal passed over Luxembourg in the F-layer, where it was thermally modulated by the Radio Lux signal:
http://durenberger.com/resources/documents/LUXEMBOURGEFFECT0235.pdf
This illustrates how sensitive the ionosphere is to external stimuli.
Someone will joke that environmentalists will protest this when they hear about “radio stations destroying the environment”. Too late, they’re already up in arms about HAARP, the DOD’s experimential research station in Alaska for studying the Luxembourg Effect, i.e. the effect of ground-based transmitters on ionospheric and auroral phenomena:
http://en.wikipedia.org/wiki/High_Frequency_Active_Auroral_Research_Program
wayne says:
January 19, 2011 at 2:41 am
Living in Zurich in the 70s, I’d turn on AFN on my radio to listen to US sports and music. I couldn’t get Stuttgart, but I could get Frankfurt, with the signal strength oscillating for about two hours after sundown. Nice to see the image confirm what I’d suspected was the cause. No cross modulation though, that would have been interesting.
Love your semi-quote from Santayana, one of my favorite quotes. If only alarmists would take it to heart.
We have been able to do relatively accurate predictions of F layer behavior for a long time. Back (not that long ago) when short wave was important for international communications, the behavior of the ionosphere was a ‘big deal’.
There is a lot of historical data about the behavior of the F layer. Ionospheric sounding involves launching an RF signal (at various frequencies) toward the ionosphere and watching how much of the signal bounced back. As far as I can tell, this was done by many governments all over the world. http://en.wikipedia.org/wiki/Ionospheric_sounding
The ionosphere during the day is influenced directly by the sun. At night, it is influenced by cosmic rays.
I don’t know if anyone is using the results of ionospheric sounding to cross check against other measures of incoming galactic radiation but the data is there. Given that some people (Piers Corbyn for instance) are using gamma rays to predict the weather, it might be interesting to see if there is any correlation between the ionospheric sounding data and climate.
@commieBob
> I don’t know if anyone is using the results of ionospheric sounding to
> cross check against other measures of incoming galactic radiation
> but the data is there.
HAARP makes a lot of its historical and current data, including radiosondes, publicly available. For example, here are some daily plots (from 2010) which could be correlated with other data.
http://maestro.haarp.alaska.edu/cgi-bin/digisonde/scaled.cgi?endTime=20100127&pwidth=1W&var=foF2
[The HAARP radiosonde sounder is down for repairs until Feb 2011, so no current data is online now]
REPLY: Normally all discussions of HARRP are deleted, due to the nutcases that think it is about weather control. In this case I’ll allow it due to it having a datasource mentioned. – Anthony
orkneygal says: January 19, 2011 at 3:36 am
Do we now have a Green Flash predictor?
No, green flash takes enough air to refract the light, and the ionosphere is waaaay too thin. For twenty years I’ve watched for green flashes over ocean sunsets while flying and never seen one. I’ve seen just about every other photometeor, though.
Whoooa, this is getting way to close to Electric Universe type Physics!!!
@Anthony
> The F-region of the ionosphere is home to the F-layer, or Appleton layer, and is
> the densest part of the ionosphere as it extends from about 200 km to
> more than 500 km above the surface of Earth.
Anthony, atmospheric density decreases with altitude, so the D- and E-layers, which are lower in altitude, are certainly more dense than the F-layer. Were you perhaps referring to electron density?
Ask the world’s HAM operators to digitize their logs and send them to a central location. Their contacts will mirror this picture.
No need to do that. Automated NCDXF ham-radio beacons are deployed world-wide to allow automatic monitoring of band conditions at selected amateur radio frequencies.
http://www.ncdxf.org/beacon/beaconschedule.html
Of course, someone has to listen to and analyze what the beacons send. Here’s what the 14Mhz and 18Mhz NCDXF and other HF analyses looks like in Alaska.
http://maestro.haarp.alaska.edu/data/spectrum2/www/beacon14.html
http://maestro.haarp.alaska.edu/data/spectrum2/www/beacon18.html
http://maestro.haarp.alaska.edu/data/spectrum2/www/hf.html
Looks like more heuristic rumination.
“The model self-consistently solves for the neutral wind driven dynamo electric field and the gravity driven electric field associated with plasma bubbles.” Uh, Oh there goes my bs detector. On top of that we have bubbles spawning bubbles which sounds a lot like science fiction. I also am not aware that science has the understanding of gravity in its back pocket. Have bubbles actually been observed (especially spawning) or are these just a bunch of heuristic claims.
NASA has long known about the diurnal bulge or the expansion of the atmosphere due to the earth’s direct exposure to the sun on the day side and it does indeed peak at about 2:30pm. The bulge involves the entire atmosphere including the F layer. So why does the article not mention anything about it?
John Day (january 19, 2011 at 3:58am)
” This signal actually heated up (in the thermodynamic sense) the ionosphere, such that it modulated other radio signals broadcasting on entirely different frequencies.”
This interpretation must be yours as nowhere in the article on the Luxembourg Effect
does it state this. It does however state that “When we attempt to explain the matter in somewhat greater detail our difficulties begin and at present there is NO generally accepted theory of this ionospheric cross-modulation, as we may, perhaps, term it.”
The word “perhaps” shows that they are not even sure this is the correct handle for it. Also, highly specific geographical conditions are required for this “effect”to happen.
Your conclusion that “This illustrates how sensitive the ionosphere is to external stimuli.” is, BASELESS.
Don S – Their contacts will mirror this picture — NOT!
I am a ham radio op. The first in Canada at age 13. I have been in and out of this hobby for the last 37 yrs and this article is junk science looking for funding. Lots of bafflegab for people to read.
All we ham ops care about in regards to shortwave communications is a peak in the solar cycle.
As mentioned above, this doesn’t seem to be new or surprising… but I wonder if the Navy’s desire to understand skip in finer detail indicates a desire to return to HF for communication.
Most communication and broadcasting is now in VHF, UHF and even SHF bands, which has left HF relatively vacant. Sort of like an older Streetcar Suburb that was, um, skipped over in the dash toward far-out areas with big lots and McMansions. I’ve been thinking it’s about time to reclaim and re-gentrify HF, which has significant advantages. Maybe the Navy is thinking along the same lines?
polistra
You can trace the decline in use of the sw band (160m – 10m) to the rise of the internet as a global communications network. It is not subject to QSB(fading) nor is vhf, uhf and above. QSB(fading) can make conditions quite tortuous when trying to communicate. Still, there is no experience quite like ferreting out a weak station on the low end (morse code is my fav) of say the 20 meter band, finding out that he is halfway around the world and that he answers your call! Now that’s wireless communication!
The article was written before they figured out how these RF heaters work:
http://en.wikipedia.org/wiki/Ionospheric_heater
Hmm, would you agree me if I base my conclusion on the Luxembourg Effect?
Imagine! A tiny transmitter sitting in a tiny room located in an extremely tiny country actually created observable effects in the Ionosphere. Eat your heart out, Sol! /sarc off
In other words, you don’t need a gigawatt to heat the ionosphere, 150kw is enough to be noticed.
http://en.wikipedia.org/wiki/EISCAT