/sci/ - Science & Math

Resident geophysicist here:

Gravity surveys are measured in "gals" named after Galileo.

<span class="math"> m a = F = \frac{G m M}{r^2} [/spoiler]
<span class="math"> a = \frac{F}{m} = \frac{G M}{r^2} [/spoiler]

a = [N]/[m]

It is a Gravity Field, that's why it has the same units as an Electric Field.

The reason OP's map is in meters is because you can display the same information as the deviation in height at a specific point of a datum ellipsoid (whose radii are defined) of mean density to achieve the measured gravitational acceleration at said point.

It's basically a different way of saying the same thing, but it assumes a standard ellipsoid and a mean density therefore it is a simplification. For the purposes, though, it's perfectly fine.