# Corrección de latitud

**1**. A correction to gravity data because of (a) variation in centrifugal force resulting from the Earth’s rotation, as the distance to the Earth’s axis varies with latitude , and (b) variation of the Earth’s radius because of polar flattening. The **Geodetic Reference System 1967** (GRS67) gives

The latitude correction amounts to

**2**. A gyrocompass correction for the rotation of the horizontal north vector as a function of latitude. (The horizontal north vector is tangent to the Earth and hence the rotation is the result of Earth curvature.)

**3**. The north-south correction to magnetic data to remove the Earth’s normal field.