Earth Sciences 1023A/B Lecture Notes - Lecture 13: Edmond Halley, Secular Variation, Magnetic Declination
18 Apr 2019
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Document Summary
Canadian ground based magnetic observatories that constantly measures the magnetic eld at that speci c time and place. Satellites are used to measure geomagnetic eld continuously because of the temporal changes generated by the outer core. Geomagnetic eld changes constantly on time scales from milliseconds to millions of years. 1. geomagnetic storms= interactions with the solar wind and earth"s magnetosphere. 2. ionospheric fields= 80-200km altitude above earth charged ions move around by differential heating and lunar tides. Since they are moving changes, they create their own magnetic elds that interact with. Secular variation= the slow (non-periodic) variation in the geomagnetic eld (due to changing magnetic patterns in the core) Large changes re ect changes in the earths core. Changes in declination= a long time scale that measures the angle between magnetic north and true north. There are non periodic declination of the earth"s magnetic eld. The shape of the eld is constantly changing > the changes are different in different places.
