magnetic variation


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Related to magnetic variation: Magnetic deviation

magnetic variation

[mag′ned·ik ‚ver·ē′ā·shən]
(geophysics)
Small changes in the earth's magnetic field in time and space.

magnetic variation

magnetic variation
In navigation, at a given place and time, the horizontal angle between true north and magnetic north measured in degrees East (+) or West (−) according to whether magnetic north lies east or west of true north. The magnetic variation indicated on a map or a chart is not a fixed quantity but is subject to change. Magnetic variation is indicated by dashed lines on maps and charts. Most maps and charts indicate the rate of annual change of variation also.
References in periodicals archive ?
AIM 1-1-18 goes on to say that a properly functioning RNAV system with a current, accurate navigation database should still fly the correct ground track for any loaded instrument procedure, despite differences in magnetic course attributable to magnetic variation source.
There are a couple of standard abnormalities in the application of magnetic variation for certified devices.
The term variometer is generally applied to any instrument that registers magnetic variations, whether it be changes in magnetic declination or any other component of the field, horizontal or vertical.
For example there is a facsimile reproduction of Bernacchi's South Polar Times article of May 1902, which bore the catchy title of "The ESCHENHAGEN MAGNETIC INSTRUMENTS and the MAGNETIC VARIATIONS and DISTURBANCES they record.
The important characteristic of this modality is that the transitory magnetic variations are removed and the effect of the regional magnetic anomaly is completely filtered, registering only those anomalies that are bound to structures located near the surface.