Earth’s magnetic field mimics solar activity

Posted: November 24, 2010 by tallbloke in solar system dynamics

Well this is interesting

Leif offered us a graph of ‘Dst’ which is a measurement of earth’s horizontal magnetic field – in the plane of the orbits of the solar system’s planets.

From: A Continuous Long-Term Record ofMagnetic-Storm Occurrence and Intensity
Jeffrey J. Love USGS Geomagnetism Program

Measurements made near the Earth’s equator of
the disturbance of the horizontal magnetic field
made during magnetic storms can be represented
by an equivalent magnetospheric ring current in
the magnetosphere. The longitudinal average of
these measurments is the Dst index, a
fundamental measure of magnetic-storm intensity.

My bold
Eyeballing this graph I noticed that the positive and negative components of the Dst index when inverted would correlate quite well with Leif Svalgaard’s solar wind reconstructions and the sunspot record. This may or may not be a novel discovery. I don’t yet know if anyone has spotted it before. Vuk is busy working on this data too, so I hope he calls by with his opinion.

This may be something already known, but I’ve never seen such a close correlation between a measure of  Earth’s magnetic changes and the sunspot and solar wind variation before. I’m awaiting responses and further discussion on this WUWT post:

[update] leif has some answers already, he says:

The negative part of Dst is determined by how much southward heliospheric magnetic field there is and that is in turn determined by how much magnetic flux on the surface of the Sun there is, which in turn is determined by how many spots there are.


The positive values of Dst come from the compression of the magnetosphere due to the increased flow pressure when a CME hits. The flow pressure increases when the density increases [and that, in turn, varies inversely with solar wind speed – low speed wind is denser], so no wonder the curves look alike [some of the time]. They must and they do, as we have known for a while. You see, when we understand some things, they make sense.

Funny how he didn’t get around to telling us before I turned the data the right way up. 😉

So the connection between the Sun and Earth is immediate, and intimate, and generates bleddy great big electric currents in the sky. Now if we can just sort out the effect of those flux tubes from the solar surface which connect with our magnetosphere…

  1. Gray says:

    Interesting tallbloke. I wonder at this recent conference and its purpose.

    Are they talking about the same phenomena, I wonder.

  2. Most interesting. What about the Earth Corona (a.k.a.”Thermosphere”), however Earth´s EM field is still very little: Cos 0.1981;19.81% and the Gravity field 78.29%, or, what is the same: Gravity= 9.81 Nm and EM Field=1.981 Nm
    What is more interesting is the equivalent of Sunspots….You guess it 🙂

  3. I appreciate Dr.Svalgaard openness as a source for us “apostates”. Thanks a lot!
    I think M.Vukcevic will give us appropiate comments.

  4. tallbloke says:

    Gray, yes, it’s all tied up in the same parcel. Good to see initiatives are under way to get a better measurement network in place.

    Adolfo, Leif said this:
    The southward component of the HMF controls the amount of energy fed into the Earth’s magnetosphere some of which [in a complicated way] end up as energy of ions [some from the solar wind and some pulled up from the ionosphere] in the [outer] Van Allan belt [the ring current]. Those ions drift around the Earth in its magnetic field while at the same time bouncing between the north and south poles and that constitutes an electrical current around the Earth. The magnetic effect at the surface of the Earth of that current we call Dst [the negative part, because the magnetic effect at the equator is opposite to the horizontal magnetic field there]. Because of collisions with the [way] upper atmosphere the ions are quickly [within hours and days] lost again and Dst reverts to its base level.

    Which is fine as far as it goes, except for one detail:

    There was a NASA article on WUWT a while back that which said a new discovery had been made that the rate of reconnections (and thus energy flow) between the Sun and Earth’s magnetosphere wasn’t just just down to the southward component but depends on the rate of fluctuation between southward and northward polarity. I can’t find it at the moment, can anyone here remember it?

  5. Tenuc says:

    Good find Rog. I too wonder why Leif hasn’t mentioned this before? – at least as far as I remember.

    Your relationship shown in the graph shows that solar EM effects have direct impact on our atmosphere and is the cause of changes to Earth global current circuit.

    Not sure what WUWT link you’re after, but is this NASA link on sun/Earth connection events any use???

  6. Magnetic “Reconnections” are the big discussion between the Electric Universe proponents and some astrophysicists who only recognize magnetism without electricity (surprisingly….poor Oersted can not rest until now). However, we can visualize it both ways: Imagine a wave as a series or succession of beautiful round “bubbles”, suddenly one of these “DIES”, blows up, giving up its energy to the surrounding media. Now think that “bubble” of transient existence as “quanta”. Max Planck thought waves give its energy in discrete amounts-exploding bubbles-. However, following the philosophical principle of “As above so below” we can observe THE SAME in every “dimension” (SIZE). What Max Planck did not see was that his “constant” (0.66252) restricted his law to a limited range of phenomena. His law was really general if, instead, are considered different “constants” for different phenomena. (For example, electric engineers use their constant for obtaining their power (energy) (0.707106781x 2=1.414213562) which is the same as adding Sin 45 deg.+ Cos 135 deg. (they don’t realize, however that Cos 135 is NEGATIVE).
    What we see, then, is, whatever the case, be it electron sized waves or anything waves, they vary according to a factor (“constant’) which is the result of the Sin and the Cosine of the angle formed by the charges which originate the phenomenon. This applies to everything, and those “reconnections”, those “quanta” dying and giving off its energy, in “discrete” amounts, back to nature, in the above case to Earth, follow the same law, no matter what the “dimension”(size) the wavelength is.

  7. @ Tenuc says:
    November 25, 2010 at 2:42 pm
    You won’t believe it (and, BTW, this can only be written in this Blog, anywhere else it would be considered apostasy):
    Those breaches, NASA has found, were known by the ancients as the “Deva loka” and “Asura Loka” (the gate of the Gods and the Gate of the Devils) 🙂
    Related to Solstices ( you see them in Stonehenge), and, of course, to the intervals in the octave, (found at Sin 15 deg., Sin 75 deg., etc).
    This is a digression, as the article above, instead, as I understand it, refers to the continuous connection between Anode Sun to cathode Earth.

  8. tallbloke says:

    Leif says:
    The real relations are with the magnetic field [B] for Dst and with the product of B and the square of the solar wind speed [V] for am ( am = 1/6*B[nT]*(V[km/s]/100)^2 ). B varies closely with SSN, but not perfectly [e.g. cycle 20]. All this is reasonably well understood [to the point where we can derive B and V from Dst and am].

  9. tallbloke says:

    Tenuc, yes!
    Thanks a lot. Leif said in response to me bringing that one up:

    “That ‘new’ discovery was just usual NASA hype. This is not new at all. The issue is that since the magnetosphere has a certain size cross section, the amount of southward field varies across the magnetosphere and the will be patches where the reconnection is good and other patches where it is bad. See page 32 of

    Clearly, the Earth’s magnetic field isn’t the simple ‘bar magnet’ of our childhood encyclopedias. 🙂