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    Short term magnetic anomalies
    From: Bob Goethe
    Date: 2017 Sep 5, 11:07 -0700

    The BBC today reported on a paper that proposes a hypothesis that the 29 sperm whales that grounded themselves over the course of a month, in Europe in 2016, did so because a solar storm caused variations in the magnetic fields that whales use in navigation.

    http://www.bbc.com/news/science-environment-41110082

    The report was fuzzy on the NATURE of the magnetic changes produced by solar storms. It did say:

    Looking specifically at the region around Shetland, the scientists found that these solar events would have caused short-term shifts in the magnetic field of up to 460km, in the area between the islands and Norway.

    I am wondering if anybody here is aware of this sort of thing, and knows the magnitude of magnetic "shifts", and a bit more of their nature.  Are we talking about changing the contour lines of magnetic variation such as would cause a change in the amount of variation in a given location, and if so, would this be significant enough to be navigationally significant for small boats?  I am assuming that a change in magnetic variation of 0.3° would be insignificant, while a change of 3.0° would be worth taking note of.

    If compass variation departs from predicted values by significant amounts from time to time, then when out of the sight of land the prudent sailor might determine the azimuth to a celestial object and verify the variation at his current location from time to time, even if he has in hand a chart with magnetic contour lines indicated.

    On the other hand, if there is no change in compass variation (or it is so small as to be lost in the noise of trying to steer a consistent course in a small boat) or if these events are vanishingly rare, then he need not worry about changes due to solar storms.

    Bob

       
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