Spaceweather.com continues its data collection concerning radiation levels at high altitudes. Check out how it varies, not with altitude, but with latitude:
Recently we encountered an interesting feature in data taken over the Pacific Ocean: a “radiation bowl.” On Nov. 30th, 2017, Hervey Allen, a computer scientist at the University of Oregon, carried our radiation sensors onboard a commercial flight from San Francisco, California, to Auckland, New Zealand: map. As his plane cruised at a nearly constant altitude (35,000 ft) across the equator, radiation levels gracefully dipped, then recovered, in a bowl-shaped pattern:
In one way, this beautiful curve is no surprise. We expect dose rates to reach a low point near the equator, because that is where Earth’s magnetic field provides the greatest shielding against cosmic rays. Interestingly, however, the low point is not directly above the equator. A parabolic curve fit to the data shows that the actual minimum occurred at 5.5 degrees N latitude.
Keep in mind that the magnetic north pole is not coincident with the north pole defined by the spin of the planet (nor that of the geomagnetic north pole, which is getting beyond my meager knowledge of physics). I wonder if there’s a correlation between this offset and the magnetic pole offset…
