MAGDAS Coordinate System

The coordinate system for MAGDAS data is the local magnetic coordinates. MAGDAS has three-axis orthogonal fluxgate type magnetometer sensors. We set up one of the axes of the sensor alined with the local horizontal field (magnetic local north which indicates the mean direciton to the magnetic north pole at the point). Other perpendicular axes are installed along the local matnetic east and the downward vertical direction. We referred these components to as the character "H", "D", and "Z". All of them are measured in nanoteslas. The total magnetic field magnitude ("F") are calculated by the following equation: F=sqrt(H^2 + D^2 + Z^2).

In summary, the magnetic field data provided by MAGDAS is

H: magnetic field strength to the local magnetic north direction, in nT
D: magnetic field strength to the local magnetic east direction, in nT
Z: magnetic field strength to the vertical down direction, in nT
F: total magnetic field strength calculated these three components, in nT

Note1: The definition of our coordinate system is different from the common one used in Intermagnet, etc.
Note2: The data recorded by old magnetometers show only relative variations, and no total magnetic field value. Please be careful if you need the absolute values for your study.