This is an article which I was very happy to come across. This is a discussion of the measured effect of the ionosphere from a gamma burst, in 2004.
While searching for more research information from Russian scientists, specifically from Tomsk State University, I've uncovered a number of interesting research papers. The following originates with the Usikov Institute for Radio-Physics and Electronics, National Academy of Sciences of the Ukraine; in conjunction with Karasin Kharkov National University (Ukraine), NASA (NY, USA), Moshiri Observatory (Japan) and Japan Aerospace Exploration Agency.
In the arena of Schumann resonances, within the discussions of the origins of Amplitude spikes, frequently in comments, and online in general, there comes a certain conceit. In many cases the cause of amplitude spikes is given as "incoming gamma/5D energies."
Personally, I am not one to simply accept generalized phrases like this. If true, I'd like to know how this happens, based on observations of the people who are tasked with such things. Let me see the physical observations and actual research.
Let me get to the point: The effect of gamma bursts from stellar sources, is that gamma flares reduce, or drop-down the Schumann Resonances.
According to "The effect of a gamma ray flare on Schumann resonances", by A. P. Nickolaenko (2004), the data shows that gamma bursts effectively drop the frequency of the vertical conductivity channel, therefore help to diminish the intensity of the SR:
"We postulate that only the 'knee altitude' is reduced by gamma rays.
Therefore, the 'electric' height of the Earth–ionosphere cavity goes down, while the 'magnetic' height remains undisturbed.
It is important that according to VLF records (Inan et al., 2007), the modification was detected at the angular distance from the center of disturbance reaching 60.
We assume therefore that the gamma ray modification may cover the whole hemisphere.
Physically, a huge reduction of the ionosphere height alters the eigenvalues of the Earth–ionosphere cavity.
Modification simultaneously brings down the peak amplitudes, peak frequencies, and the quality factors of all Schumann resonance modes.
In our computations that account for the daynight non-uniformity, the PUK model was used (Pechony and Price, 2004) with the 20 km reduction of knee height at the dayside.
[...]
We conclude that computations predict essentially the same modification regardless of particular model: gamma rays abruptly reduce all resonance parameters.
It is important that sudden alterations occur simultaneously at all resonance
modes, and hence we must look for the similar discontinuity pattern in experimental ELF sonograms around the occurrence time of gamma flare"
To me, this explains what I needed to know. Gamma flares do not cause an amplitude burst, because the height of the 'vertical conductivity channel' has reduced by many kilometers.
If the lower resonances (7.8/14.1/20.7 Hz) are not intense, or strongly 'ringing'; then summarily there will be no higher, or upper harmonics. (27.1/33.3/39.9HZ)
What is the "Knee ionosphere model"?
(Part 2)
THREE DIMENSIONAL FINITE DIFFERENCE TIME DOMAIN
MODELING OF SCHUMANN RESONANCES ON EARTH AND
OTHER PLANETS OF THE SOLAR SYSTEM
A Thesis in Electrical Engineering, by Heng Yang
["The effect of a gamma ray flare on Schumann resonances", by A. P. Nickolaenko1, et al.*Published: 7 September 2012 ]
Abstract. We describe the ionospheric modification by the SGR 1806-20 gamma flare (27 December 2004) seen in the global electromagnetic (Schumann) resonance.
The gamma rays lowered the ionosphere over the dayside of the globe and modified the Schumann resonance spectra.
We present the extremely low frequency (ELF) data monitored at the Moshiri observatory, Japan.
Records are compared with the expected modifications, which facilitate detection of the simultaneous abrupt change in the dynamic resonance pattern of the experimental record.
The gamma flare modified the current of the global electric circuit and thus caused the “parametric” ELF transient. Model results are compared with observations enabling evaluation of changes in the global electric circuit.
1 Introduction
Monitoring of the global electromagnetic (Schumann) resonance allows for studying both the Earth–ionosphere cavity and the natural sources of radiation-lightning strokes (Nickolaenko, 2002).
We compare the experimental and model results concerning the impact of the powerful gamma ray flare from SGR 1806-20 that occurred on 27 December 2004.
Since 1979 a couple of intense gamma ray flares took place arriving from the extra-terrestrial sources.
Records of remote VLF transmitters indicated the ionosphere depression caused by the gamma rays (Inan et al., 1999, 2007; ), but an attempt
was unsuccessful at finding any changes in the Schumann resonance records caused by the gamma flare from SGR 1900+14 on 27 August 1998 (Price, 2001).
In this paper we report a successful detection of changes in the Schumann resonance spectra during the intense gamma ray flare SGR 1806-20
(27 December 2004).
The records were performed at the Moshiri observatory, Japan.
Experimental material is compared with the model predictions for the Schumann resonance background signal based on the “knee” ionosphere model.
Detailed description of the gamma ray event can be found in the papers by Hurley et al. (2005), We mention only the minimal information here.
The flare occurred around 21:30:26UT when the hard X/gamma rays arrived atthe dayside of the Earth.
Radiation came from a neutron star 30–40 thousand light years away.
The peak flow exceeded the most intense solar flares by five orders of magnitude, and itwas 100 times greater than the SGR 1900+14 gamma flare of 1998.
2 Conductivity profile of the lower ionosphere
The knee ionosphere model is used for computing the parameters
of Schumann resonances in the uniform Earth–ionosphere cavity (Williams et al., 2006).
The PUK model is applied for the cavity with day-night non-uniformity (Price
and Pechony, 2004).
We postulate that only the “knee altitude” is reduced by gamma rays.
Therefore, the “electric” height of the Earth–ionosphere cavity goes down, while the “magnetic” height remains undisturbed.
It is important that according to VLF records (Inan et al., 2007), the modification was detected at the angular distance from the center of disturbance reaching 60.
We assume therefore that the gamma ray modification may cover the whole hemisphere.
Physically, a huge reduction of the ionosphere height alters the eigenvalues of the Earth–ionosphere cavity.
Modification simultaneously brings down the peak amplitudes, peak frequencies, and the quality factors of all Schumann resonance modes. In our computations that account for the daynight non-uniformity, the PUK model was used (Pechony, 2004) with the 20 km reduction of knee height at the dayside.
Bearing in mind the global nature of Schumann resonance, we applied the 10 km depression over the whole globe in the model of uniform Earth–ionosphere cavity (Nickolaenko, 2010).
We compare the results of both approaches and find that the day-night asymmetry has a minor impact on the quantitative effect of the gamma rays.
3 Modifications of Schumann resonance spectra
Prior to processing the experimental record, we found outwhat kind of modification should be sought in the observa-tional data (Nickolaenko and Hayakawa, 2010). The abovemodelsoftheEarth–ionospherecavitywereusedforthispur-pose combined with the modern data on the global lightningsource distribution. The “physical” parameters of the stan-dard and disturbed ionospheres are listed below.We adopt the knee altitude
at the 55km altitude for thefrequency of 10Hz (Greifinger, 1978).
Vertical conductivity profile has the scale heights 8Hz, which logarithmically varies with frequency.
Conductivity profile at the“magnetic” altitude has a definite scale height (Mushtak, 2002).
Gamma rays globally reduce the knee altitude
H KNEE from 55 to 45km, and relevant parameters were used in computations of ELF spectra (Nickolaenko, 2010).
When accounting for the cavity day-night asymmetry, we used the PUK model (Pechony, 2004).
The ionosphere is subdivided into the day and night hemispheres, and the knee model is used for each of them, only, parameters at these two sides are different.In particular,
These parameters were used inthe procedure of resolving the 2-D (two-dimensional) telegraph equations for Schumann resonance.
Two spatial distributions of thunderstorms were used.
The simple one has the lightning strokes uniformly distributed worldwide.
A more realistic model implies the global distribution acquired by the Optical Transient Detector (OTD).
This space-borne sensor recorded optical flashes from thelightning strokes worldwide during 5 years of observations.
The final results were presented as global maps of lighting activity corresponding to every hour UT and each month of a year.
Since the gamma rays arrived at 21:30UT, we averagedthe OTD maps for 21 and 22h in our computations.
Figure 1 shows the numerical sonogram of Schumannresonance around the moment of gamma ray burst (t=0) (Nickolaenko and Hayakawa, 2010).
Thunderstorms were positioned in accordance with the OTD data. Resonance spectra were computed with the 10s time step, and the height modification was described by Eq. (1) with the initial global reduction of 10km instead of 19km.
The sonogram of Fig. 1 clearly shows an abrupt down-ward shift of the Schumann resonance pattern at the onset of gamma ray flare.
It slowly returns to the regular configuration afterwards.
Thus, one has to search for a sudden drop inexperimental sonograms at the time of the gamma burst oc-currence. To stress the outline of modification, we draw the levels 240 and 260 a.u. by thick lines in Fig. 1.
These contours will be helpful in comparing observational data.
Figure 2 shows the impact of gamma rays in both the uniform Earth–ionosphere cavity (upper plot) and in the non-uniform cavity (lower plot).
The OTD source distribution is used in both cases.
The spectra were computed for the vertical electric field component by using the 2-D telegraph equations with the PUK day-night model (Pechony et al., 2007).
As one may see from the figure, dynamic spectra of Schumann resonance in both frames behave similarly: there is an abrupt drop in the resonance pattern.
Additional data are given in Fig. 3 comparing amplitude variations in the uniform and non-uniform Earth–ionosphere cavities.
The observer is placed at “Palmer” Antarctic station where the gamma flare was detected in VLF transmissions.
Both uniform and OTD spatial distributions of lightning strokes were used combined with two models of the Earth–ionosphere cavity.
The inset in Fig. 3 shows the amplitude reduction with higher temporal resolution. By comparing the black line (OTD lightning distribution in the non-uniform cavity) with the blue curve (OTD distribution and the uniform cavity), we observe that effect of the ionosphere day-night asymmetry is
insignificant.
The highest deviation among the curves is pertinent to the uniform distribution of lightning strokes.
Except for this systematic deviation, the general behavior remains
the same: an abrupt reduction reaching 30% and a gradual
recovery.
We conclude that computations predict essentially the same modification regardless of particular model: gamma rays abruptly reduce all resonance parameters.
It is important that sudden alterations occur simultaneously at all resonance
modes, and hence we must look for the similar discontinuity pattern in experimental ELF sonograms around the occurrence time of gamma flare.
(Cite: Ann. Geophys., 30, 1321–1329, 2012; www.ann-geophys.net/30/1321/2012/
doi:10.5194/angeo-30-1321-2012 © Author(s) 2012. CC Attribution 3.0 License.)
[*A. P. Nickolaenko1, I. G. Kudintseva2, O. Pechony3, M. Hayakawa4, Y. Hobara5, and Y. T. Tanaka6
1Usikov Institute for Radio-Physics and Electronics, National Academy of Sciences of the Ukraine,
12, Acad. Proskura Street, Kharkov 61085, Ukraine
2Karasin Kharkov National University, 4, Svoboda sq., Kharkov 61077, Ukraine
3NASA Goddard Institute for Space Studies and Columbia University, New York, NY, USA
4Advanced Wireless Communications Research Center and Research Station on Seismo Electromagnetics, The University of
Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
5The University of Electro-Communications, Graduate School of Informatics and Engineering, 1-5-1 Chofugaoka, Chofu
Tokyo 182-8585, Japan
6Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, 229-8510, Japan
Correspondence to: M. Hayakawa (hayakawa@whistler.ee.uec.ac.jp). ]
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