Variation in magnetic declination can affect navigation and surveying in the cave
In recent years, magnetic north has been moving at an unusually high speed, which may affect magnetic declination and thus navigation and cave detection systems.
Magnetic declination refers to the angular difference between true north and magnetic north.
This difference varies by location and over time.
In the last century, the average speed of movement of the magnetic north was about 15 kilometers per year.
Since the new century, this speed has increased significantly until today, approximately 55 kilometers per year.
This acceleration in the movement of the magnetic north makes the indicators shown on geographical maps unreliable.
In fact, geographic maps show the average value of the magnetic declination at the center of the map and its annual variation, based on geomagnetic models of the Earth's magnetic field.
However, current geomagnetic models differ from those used in the past, resulting in inaccurate current anomaly values being calculated.
The National Centers for Environmental Information (NOAA) studies and publishes a model of the Earth's geomagnetic field from which the magnetic declination of various points on the Earth's surface can be extracted.
The value of magnetic declination is used by all navigation systems, but also by those who use a compass to orient themselves in the environment.
Therefore, it is important to know the correct value of magnetic deflection.
The NOAA website provides the possibility of calculating the magnetic declination with the latest geomagnetic model in order to obtain the correct value for the position of interest to us.
This change in magnetic declination can have major practical implications.
For example, at airports around the world, runways are marked with numbers indicating their orientation relative to the magnetic north pole.
The change in magnetic declination forces airports to update their runway designations in order to allow landing aircraft pilots to perfectly align themselves with the runway using the on-board compass.
It is important to be aware of this difference and use the latest geomagnetic models to calculate the correct magnetic declination.
Source and link to NOAA website: https://www.mondogeo.com/2019/02/07/la-declinazione-magnetica-in-italia/
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