Really enjoyed your Stanford presentation on “Becoming a Scientist” and today’s comment.
“Leif, for a man who is excellent, when it comes to the narrow range of your expertise, you seem unaware of worlds outside your canyon.
When people come into my canyon I tell them the facts. And how do you justify to state that my range of expertise is ‘narrow’? as compared to many commenters here who have no expertise”.
Where do you think your research into the Sun’s magnetic fields is going to lead (read your paper from the late 70’s)?
Judith Curry’s blog posts over the past couple weeks have been a nice compliment to your approach to science and learning. I hope you have another wonderful 30 years.
I follow your comments on WUWT with interest and have read many of your research papers, a great number of the earlier of which concern the IMF.
There being no magnetic monopoles, I understand the IMF to be sum of all the magnetic fields associated with each of the bodies in our solar system, capable of producing the same – the sun being clearly by far and away the largest body.
Since we know much more of the shape of the IMF from time to time, and the influence which the solar MF has upon it, I wondered whether research has been published considering whether the IMF – given particular patterns of field lines and strength in particular locations within the system at particular times – might be able to influence the geomagnetic field so greatly that the IMF might be able to initiate reversals (or excursions as once known) in the Main Field of this planet.
This would stand as a tentative alternative to those theories of geomagnetic reversals et al based on internally generated changes in Earth’s core.
The IMF is 10,000 times weaker than the Earth’s magnetic field at the surface, and a million times weaker than the core field [which is where the surface field comes from]. Even with the occasional [rare] enhancements of the IMF during CMEs the IMF cannot influence the core field. This is apart from the fact that the so-called skin-depth is so shallow that magnetic field changes cannot [and do not] enter the core at all.
Thank you for that clear response. Is it your view additionally that there can likely be no major impact on (that is to say, not simply a magnetic storm but sufficient impact to initiate a reversal in) the earth’s magnetic field from solar effects alone?
I am referring to massive CME’s, or changes in the solar wind speed and density arising from some other solar activity.
The Earth’s strong magnetic field and the relatively high conductivity of the mantle [plus the very high conductivity of the core] combine to shield our main magnetic field from solar mischief. So, don’t expect any effect form solar activity on the core field. At the surface there can be inductive effects from rapid changes in the external magnetic field. These effects can be sever: burnout transformers, corrosion of pipelines, see silde 13 of http://www.leif.org/research/On-Becoming-a-Scientist.pdf
Thank you, I appreciate your response. I would still like to have an opportunity to re-read your papers on the IMF in particular.
In the meantime, am right in thinking that absent the solar wind, the sun facing section of the earth’s field would likely expand until it met with equal force and intensity the sun’s own field – i.e that the enormous discrepancy between the two field strengths at the sun-ward boundary of earth’s field is due principally to the compressing force of that wind?
Also in the time since you wrote your earlier papers on the IMF, has science determined with any more clarity the existence, if any, and strength of the magnetic fields of the other bodies in our solar system?
Most bodies in the solar system have magnetic fields, some [e.g. Jupiter] much stronger than the Earth’s; some [e.g. the Moon] much weaker and disorganized.
The Earth’s magnetic field is 10,000 times stronger than the the magnetic field in the solar wind, but decreases with the cube of the distance, so out at something like 10 earth radii is so weak that it matches the energy of the solar wind and a ‘stand-off’ is achieved. Outside of that the solar wind is stronger, inside the Earth’s field is stronger.
Leif, in discussions of SH SSW, polar vortex highs etc., you refer to their rarity. I take that as a signal to investigate if something unusual is happening, or just something previously unnoticed.
The role of magnetic field strengths, solar wind, AP indices, CME’s and GCR’s seems important. I note plenty of SH polar vortex blockades in recent years. I would value your comments on cause and effect, changes in detection abilities, and if semi-cyclic solar activities are likely to be important here, etc.? Thanks, Brett Keane, New Zealand