Alternate Definitions for SM

Solar Magnetic - A geocentric coordinatesystem where the Z axis is northward along Earth's dipole axis, X axis is inplane of z axis and Earth-Sun line, positive sunward. See Russell, 1971.

This system has its Z axis parallel to the Earth's magnetic dipole axis (positive North) and its Y axis perpendicular to the plane containing the dipole axis and the Earth-Sun line (positive in direction opposite to the Earth's orbital motion). The direction of the geomagnetic field in the outer magnetosphere is well-ordered by this system. It is the preferred system for defining magnetic local time in the outer magnetosphere.