Definition
The angle at the centre of a sphere which is tangent to the SPHEROID along the GEODETIC EQUATOR, between the plane of the EQUATOR and the radius to the point intersected on the sphere by a straight line perpendicular to the plane of the EQUATOR and passing through the point on the SPHEROID whose parametric latitude is defined. Parametric latitude is an auxiliary LATITUDE used in problems of GEODESY and CARTOGRAPHY. Also calledreduced latitude, geometric latitudeor eccentric angle.