Free-air gravity anomaly

In geophysics, the free-air gravity anomaly, often simply called the free-air anomaly, is the measured gravity anomaly after a free-air correction is applied to correct for the elevation at which a measurement is made. The free-air correction does so by adjusting these measurements of gravity to what would have been measured at a reference level. For Earth, this reference level is commonly taken as the mean sea level.

The free-air gravity anomaly is given by the equation:

Here, ${\displaystyle g_{F}}$ is the free-air gravity anomaly, ${\displaystyle g_{obs}}$ is observed gravity, ${\displaystyle g_{\lambda }}$ is the correction for latitude (because planetary bodies are not perfect spheres), and ${\displaystyle \delta g_{F}}$ is the free-air correction.

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