| Term: | DM |
| Definition: |
As with the solar magnetic system, the Z-axis of the dipole meridian system (DM) is chosen along the north magnetic dipole axis. However, the Y-axis is chosen to be perpendicular to a radius vector to the point of observation rather than the Sun. The positive Y direction is chosen to be eastwards, so that the X-axis is directed outwards from the dipole. This is a local coordinate system, in that it varies with position, however, since the X-Z plane contains the dipole magnetic field it is quite useful. |