A REVISED CORRECTED GEOMAGNETIC COORDINATE SYSTEM FOR EPOCHS 1985 AND 1990

A new set of corrected geomagnetic coordinates (CGM) has been calculated from the magnetic field model DGRF for Epoch 1985 and the IGRF model for Epoch 1990. A new approach to determine the 'dip' magnetic equator has been developed, which is based on the vertical (along Re) projection on the Earth's surface of the B-minimum value point (apex) on each geomagnetic field line. A strip along the 'dip' magnetic equator line has been defined where the corrected geomagnetic coordinates could not be found by the definition of CGM. Linear interpolation between the locations of the two last definable CGM latitudes in both hemispheres has been used to calculate the CGM longitudes in the equatorial region. Interpolation between locations of the last definable CGM latitude and 'dip' equator in both hemispheres has been used to calculate the CGM latitudes in this region. The constant B-min geomagnetic coordinate system (CBM) is proposed and analysed to replace CGM in the equatorial region.