The Hum
Intensity in
Dr Chris Barnes Bangor Scientific
Consultants. 1st published
online November 2011 email mamager@bsec-wales.co.uk
Abstract
It
has recently been shown that the Hum may be due to interaction between world
power systems of different frequency standards. It has further recently been shown that Hum
levels are maximised when there are what seem like artificial signals and/or
narrow band spikes in pulsation magnetometer recordings and minimised when these are absent. In this present study we seek a far more
quantitative approach, subjective Hum
levels on specific dates and importantly at specific times are compared with
quantitative plots, so called IMAGE
electrojet indices, by courtesy of the Finnish Meteorological
Institute. The method uncovers a
profound and indisputable relationship. Essentially when the electrojet current components IU and IL are
balanced and at zero or close to zero the Hum intensity maximises. On the other hand when they are finite and
imbalanced the Hum intensity is zero or minimised. The hypothesis is twofold. Firstly, it is
proposed that the electrojet will be easier to modulate artificially at minimal
current resulting in maximum artificial infrasound radiation and maximum
artificial ground (telluric) current flow in turn yielding maximum artificial
electro and magneto –seismic effect, i.e. maximum Hum. Secondly, when the
electrojet currents are large and imbalanced external modulation will be more
difficult and in any event there will be maximum natural infrasonic and seismic
noise and maximum natural telluric signal amplitudes and hence no or little
opportunity for the Hum. Interestingly
these criteria will be expected to minimise not only a Hum caused by power line
interactions but also Hum caused by virtually any anthropogenic
interactions. Observation of the
behaviour of IU and IL also explains why the Hum is usually but not exclusively
regarded as a nocturnal phenomenon.
Introduction
The Hum is an acoustic
(possibly also magneto- acoustic) phenomenon known about since the 1970's is
somehow related to modern infrastructure and recently has been receiving much
more press publicity and partially thanks to the present author, scientific
credence. Those afflicted either
physically hear or otherwise somehow perceive a characteristic sound. This was
tone matched by some Hum hearers in the
Recently there
have been more amateur proponents of UHF/Microwave theories of the Hum. The
author has received several anecdotal reports from such individuals in the
Some
cases of the Hum have been shown to be due to simple low frequency noise
pollution but others, indeed by far the greater majority, have proved far more
elusive.
Any
proper explanation relevant to this majority of Hum cases must be able to
account for the start up of the phenomenon in the
Inevitably
all kinds of signals which perturb space weather i.e. the ionosphere and the magnetosphere, the
classic example is lightning. In other words whether we like it or not there is
an inexorable coupling between the two.
So perhaps it is no great surprise that anthropogenic signals directed
from earth have some influence too. Classic manifestations of space weather in
the ionosphere are the electrojets. An electrojet is an electric
current which travels around the Earth's
ionosphere. There are two electrojets: above the magnetic equator (the equitorial
electrojet), and near the Northern and Southern Polar Circles (the Auroral Electrojets). Electrojets are Hall currents carried
primarily by electrons at altitudes from 100 to 150 km. In this region the
electron gyro frequency (Larmor frequncy)
is much greater than the electron-neutral collision frequency. In contrast, the
principal E-region ions (O2+ and NO+) have gyrofrequencies much lower than the
ion-neutral collision frequency. Kristian Birkeland5 was the first to suggest that polar electric currents
(or auroral electrojets) are connected to a system of
filaments that flow along geomagnetic field lines into and away from the polar
region. The Finnish Meterological
Institute provides a website6
which calculates various components of the current magnitudes of the Polar (Auroral) Electrojet from observations on a substantial
chain of magnetometers. The term 'auroral electrojet' is the name given to the large
horizontal currents that flow in the D and E regions of the auroral
ionosphere. Although horizontal ionospheric currents can be expected to flow at
any latitude where horizontal ionospheric electric fields are present, the auroral electrojet currents are remarkable for their
strength and persistence. There are two main factors in the production of the
electrojet. First of all, the conductivity of the auroral
ionosphere is generally larger than that at lower latitudes. Secondly, the
horizontal electric field in the auroral ionosphere
is also larger than that at lower latitudes. Since the strength of the current
is directly proportional to the vector product of the conductivity and the
horizontal electric field, the auroral electrojet
currents are generally larger compared to those at lower latitudes. During
magnetically quiet periods, the electrojet is generally confined to the auroral oval. However during disturbed periods, the
electrojet increases in strength and expands to both higher and lower
latitudes. This expansion results from two factors, enhanced particle
precipitation and enhanced ionospheric electric fields. If then elctrojets
are manifestations of space weather we might expect a connection with the
Hum. It is the purpose of this present
work to establish what that relationship might look like
Experiment
and data sources
The experimental data has been
available for several years and consists of private records of the author in which his personal
experience of the Hum was logged, dates, times and relative amplitude or
relative distress level. This data
can be compared with data from the Finnish Meteorological Institute Website
which has archived plots of the image elctrojet
indices built up by calculation from a significant chain of World
magnetometers. IMAGE
electrojet indicators are simple estimates of the total eastward and westward
currents crossing the magnetometer network. Their definition is quite similar
to that of the standard AL, AU and AE indices. Since the introduction of the AE
indices by Davis and Sugiura [1966],
scientists have relied on the indices to monitor the level of geomagnetic
disturbance resulting from the auroral electrojets
and hence, by proxy, to specify the state of the magnetosphere and the
ionosphere. The AE index was defined by the separation between the upper
and lower envelopes of the superposed H component plots from auroral-zone magnetic observatories. The upper and lower
envelopes were defined as the AU and AL indices, respectively
Thus, there is the relationship given by AE = AU - AL.7
In the case of IMAGE indiicators,
for each timestep, IL(t) = min({X(t)}), where {X(t)}
stands for the (geographic) north components of the magnetic field measured at
the selected stations. In the same way, IU(t) =max({X(t)}), and IE = IU -
IL. Further information on the
methodology of the IMAGE indicators is available from Ari Viljanen, P.O. Box 503
FIN-00101 Helsinki,
Finland.
Results and
Discussion
With several years worth of available data there is the potential for a far
more in depth, but horrendously time consuming study. However, in order to get
these very important results released into the public domain as soon as
possible the data sets have been limited to a dozen of the most significant Hum
and no Hum periods in late 2010 through to August 2011. The Finnish data is an
archive data set and sadly not available in real time otherwise it would make
an excellent predictor for the Bangor Hum.
A series of
plots of IL (blue) (lower) and IU (red) (upper) indices follow together with
original comments in quotation marks on Hum intensity taken from the diary of
the author.
Figure 1:
Figure 2:
Figure 3:
Figure 4:
Figure 5:
Figure 6:
Figure 7:
Figure 8:
Figure 9:
Figure 10:
Figure 11:
Figure 12:
Despite there being a huge amount of data above, the analysis is striking simple and obvious but the significance for Hum sufferers is profound. When IL and IU are at or close to zero and closest to each other this is when the Hum is maximised. In figures 5-8 and 12 the original diarised comments of the author indicate specific times when he experienced the phenomenon of the Hum subjectively at its worst and these times correspond exactly for those figures the closest approaches of IL and IU to one another and to zero.
Conversely when IL and IU are furthest apart, particularly when IL has a large negative value and/or when IU is positive then there is no Hum. Also in nine out the twelve results considered IL and IU fulfil this condition particularly with IU positive mainly in daylight hours which helps explain anecdotal reports of the Hum being mainly a nocturnal phenomenon, assuming we can make the extrapolation from the Bangor Hum to ‘Hums’ in general. The plots also offer an additional explanation as to why the Hum is heard by some to fade in and out or even to switch on and off. This will simply be governed by the time rate of slope of IL and IU towards each other and zero. The steeper this gradient, the more likely there will be perceived a fairly abrupt switch on of the Hum.
The overall explanation offered
here is two fold. Firstly it is proposed that the elctrojet will be easier to modulate artificially at
minimal current resulting in maximum artificial infrasound radiation and
maximum artificial ground (telluric) current flow in turn yielding maximum
artificial electro and magneto –seismic effect, i.e. maximum Hum. Secondly when the electrojet currents are
large and imbalanced external modulation will be more difficult and in any
event there will be maximum natural infrasonic8 and seismic
noise and maximum natural telluric signal amplitudes9 and
hence no or little opportunity for the Hum.
Interestingly these criteria will be expected to minimise not only a Hum
caused by power line interactions but also Hum caused by any anthropogenic
ground borne interactions, seismic or electromagnetic. This does not rule out
therefore Hums caused by gas mains, container vessels and Hydro-power plants,
for example. Nor is it incompatible with previous observations of the author
relating to earthquakes and the stress and tilt factors affecting seismic
propagation of the Hum. It is certainly worth pursuing further investigation of
the behaviour of IL and IU before and after large earthquakes. There is of
course a natural growing interest in the scientific community in potential
methods for earthquake prediction.
These results offer further hope to Hum suffers. There is already a US Internet site which provides space weather ‘forecast’10. Perhaps, hopefully, in the not too distant future we will also see it or similar providing a ‘Hum forecast’. The real upshot is that perhaps Hummers in addition to simply having oversensitive hearing11 may actually be a very privileged group of individuals with a sort of sixth sense who are more highly tuned than most to the earth’s natural signals and magneto-acoustic outputs. Such sensitivity, for example prior to earthquakes, is well known elsewhere in the animal kingdom12. Yet in humans the downside of such sensitivity is the inability to cope with or process anthropogenic modulation of earth’s natural signals which manifests as the Hum.
Acknowledgements
The author wishes to acknowledge the following organisations
1. Finnish Meteorological Institute.
2. Spaceweather.com
The author wishes to acknowledge the following individuals
References