From the Helmholtz Association of German Research Centres
Rapid changes in the Earth’s core: The magnetic field and gravity from a satellite perspective
Annual to decadal changes in the earth’s magnetic field in a region that stretches from the Atlantic to the Indian Ocean have a close relationship with variations of gravity in this area. From this it can be concluded that outer core processes are reflected in gravity data. This is the result presented by a German-French group of geophysicists in the latest issue of PNAS (Proceedings of the National Academy of Sciences of the United States).
The main field of the Earth’s magnetic field is generated by flows of liquid iron in the outer core. The Earth’s magnetic field protects us from cosmic radiation particles. Therefore, understanding the processes in the outer core is important to understand the terrestrial shield. Key to this are measurements of the geomagnetic field itself. A second, independent access could be represented by the measurement of minute changes in gravity caused by the fact that the flow in the liquid Earth’s core is associated with mass displacements. The research group has now succeeded to provide the first evidence of such a connection of fluctuations in the Earth’s gravity and magnetic field.
They used magnetic field measurements of the GFZ-satellite CHAMP and extremely accurate measurements of the Earth’s gravity field derived from the GRACE mission, which is also under the auspices of the GFZ. “The main problem was the separation of the individual components of the gravity data from the total signal,” explains Vincent Lesur from the GFZ German Research Centre for Geosciences, who is involved in the study. A satellite only measures the total gravity, which consists of the mass fractions of Earth’s body, water and ice on the ground and in the air. To determine the mass redistribution by flows in the outer core, the thus attained share of the total gravity needs to be filtered out. “Similarly, in order to capture the smaller changes in the outer core, the proportion of the magnetic crust and the proportion of the ionosphere and magnetosphere need to be filtered out from the total magnetic field signal measured by the satellite,” Vincent Lesur explains. The data records of the GFZ-satellite missions CHAMP and GRACE enabled this for the first time.
During the investigation, the team focused on an area between the Atlantic and the Indian Ocean, as the determined currents flows were the highest here. Extremely fast changes (so-called magnetic jerks) were observed in the year 2007 at the Earth’s surface. These are an indication for sudden changes of liquid flows in the upper outer core and are important for understanding the magneto-hydrodynamics in the Earth’s core. Using the satellite data, a clear signal of gravity data from the Earth’s core could be received for the first time.
This results in consequences for the existing conceptual models. Until now, for example, it was assumed that the differences in the density of the molten iron in the earth’s core are not large enough to generate a measurable signal in the earth’s gravitational field. The newly determined mass flows in the upper outer core allow a new approach to Earth’s core hydrodynamics.
“Recent changes of the Earth’s core derived from satellite observations of magnetic and gravity fields”, Mioara Mandea, Isabelle Panet, Vincent Lesur, Olivier de Viron, Michel Diament, and Jean-Louis Le Mouël, PNAS 2012; doi:10.1073/pnas.1207346109
http://www.pnas.org/content/early/2012/10/11/1207346109.full.pdf
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Another reminder of how little we know for sure about how the Earth actually functions…
Interesting. When you think about it the minute fluctuations of gravity make sense.
Perhaps there is more in TFA, but I’m not finding the graphic to be compelling evidence of correlations between the two, not averaged over the globe. I don’t argue that there aren’t any, but I fail to see it in the picture. Perhaps a systematic computation of the spatially and/or temporally averaged correlation function reveals one, but the picture not so much.
rgb
And they, of course, do not entertain the idea that the changes in the core field are caused by the Sun, or any external agent [jupiter shine or whatever]. This is real science, and not hand waving.
Interesting article and musings here on diamagnetism and the repulsion effect of water and the jet stream patterns which affect climate change:
http://geologymaster.com/cctext3.htm
A change in the position of a magnetic anomaly has the potential to alter the amount of gcr reaching the Earth and it’s relative effect. A localised increase in gcr would be more likely to increase cloud cover if it occurred over ocean than over desert.
So where does this leave the measurements of ice loss/gain as measured by Grace for Antarctica and Greenland. If the gravity changes the measurements may be bogus.
Fascinating.
I would have thought the area to concentrate on was around Patagonia. It seems from figure4 that it is the epicentre of a gravitational oscillation the propagates out across the Pacific and Southern oceans and up at least as far a Mexico.
Correct link for the overall article:
http://www.pnas.org/content/early/2012/10/11/1207346109.abstract?sid=b763519b-f73a-48b0-8931-54bf47d153af
Movie 2 is especially interesting. You can see a strong gradient developing between eastern North America and Greenland; higher gravity in NA and lower in Greenland. What’s right in the middle of that gradient? The North Magnetic Pole, which is accelerating quickly toward the Greenland end of that gradient.
Connects with something I’ve been wondering about:
http://polistrasmill.blogspot.com/2012/09/no-it-doesnt-unless.html
And that is not all, as I have already shown, but it is strongly disputed by some experts:
http://www.vukcevic.talktalk.net/EarthNV.htm
http://www.vukcevic.talktalk.net/TMC.htm
One step at a time, and we’ll get there eventually.
“The main field of the Earth’s magnetic field is generated by flows of liquid iron in the outer core”.
Not possible. Iron heated above 770C, the Curie point, loses its magnetism. Liquid iron is much hotter than 770C.
http://en.wikipedia.org/wiki/Curie_temperature
Above 770C iron changes from a ferro-magnet to a para-magnet. The difference is that a para-magnet needs an external source to induce magnetism. The most likely source for this external excitation is the Sun’s magnetic and electrical fields.
OT Great tip!
Here is a NEW video from the Sidney Institute.Salbys lecture is real dammening with new arguments and data .Its a real CAGW killer! Check the graphs especially presented (27 min).
Isn’t that blue area near Australia the place where they find high satellite sea level?
http://sealevel.colorado.edu/content/map-sea-level-trends
Lower gravity … higher sea level?
@sunshinehours1
Actually no. Higher gravity = higher sea level, as the seawwater mass is attracted to and mounds up over seabed areas of anomalously high mass/gravity, eg over subemerged seamounts that rise from the deep ocean floor, which can be detected in satellite-borne radar altimeter surveys on account of the elevated sea surface that rises up (ever so slightly) over them.
rgbatduke says: October 23, 2012 at 5:23 am
Perhaps there is more in TFA, but I’m not finding the graphic to be compelling…
………
They were looking in a wrong place, here is one more convincing
http://www.vukcevic.talktalk.net/HudsonBay.htm
Leif Svalgaard says:
October 23, 2012 at 5:26 am
And they, of course, do not entertain the idea that the changes in the core field are caused by the Sun, or any external agent [jupiter shine or whatever]. This is real science, and not hand waving.
We can all see how paranoid you are with respect to solar system drivers. The old guard is fighting, but the writing is on the wall.
I was wondering if the changes in gravity are enough to effect air pressure, changing an areas ability to either form or alter the pressure extremity of masses of air, thereby providing a shift in climate, by changing the likelihood or degree of high or low pressure centers’ formation.
“the measurement of minute changes in gravity caused by the fact that the flow in the liquid Earth’s core is associated with mass displacements. ”
I believe the key word is minute. For 99 percent of practical applications the earth’s gravity can be modeled as a emanating from a single point in the geometric center of the spheroid. Shifts in density thousands of miles down must be borderline immesurable. Anyone got a unit? 1.0e-N g’s?
Thank you for scientific confirmation of what many of us have long suspected…
my scale lies!
This is very interesting. I think it is a good start and little more. Way to many unknowns, to many assumptions and to narrow a hypothesis focus. Never the less it calls into question some of the earlier assumptions about the core, liquid-solid or in between. That in itself is a progress type step.
Interesting.
Once, a long time ago now, I was a navigator in Strategic Air Command. Back in the days of paper, pencil, circular slide rule, and celestial, the only way to navigate over large tracts of open water (or ice) was by dead reckoning aided by clestial observations. Through most of the 1960s I used to fly between the Hawaiian Islands and the Marianas Islands fairly often. One thing I learned quickly was that the usually reliable N-1 fluxgate compass became unreliable on the transit between Honolulu and Guam. Mid-way between Honolulu and Guam the deviation between what the N-1 told me the mag heading was and what a celestial heading check said it actually was differed by as much as five degrees. That much deviation is guaranteed to get you way off course quickly. In all the years of the 1960s I made that crossing I was always careful to keep a constant check of my heading by celestial means over the tract of open ocean between Honolulu and Guam. The compass deviation was always there in spite of what my charts indicated.
I assume that there was some localized change in gravity that changed the magnetic field, and thus the magnetic heading, more than what my charts said was the value I should be using.
Leif, you missed the thread where the WUWT demolished the credibility of Grace. Sorry according to the folks here its data is total garbage.
Geoff Sharpe: the writing is on the wall.
Hmm. The writing may support Dr. Svalgaard’s choice of relevant phenomena. I believe the text was something like “weighed in the balances and found wanting.”
: > )
Steven Mosher says:
October 23, 2012 at 8:29 am
Sad that you have to resort to painting all with one big brush. Your desperate posts are getting tiresome.
Leif Svalgaard says:
October 23, 2012 at 5:26 am
And they, of course, do not entertain the idea that the changes in the core field are caused by the Sun, or any external agent [jupiter shine or whatever]. This is real science, and not hand waving.
—
First off, that level of snark is beneath anyone who claims to be a scientist.
But beyond that. These scientists haven’t proposed a mechanism by which the changes in gravity should be correlated to changes in the magnetic field. All they have done is document a correlation.
Yet for some reason, this correlation is “science”. But the others who point to correlation are charletons.